prom-client - npm Package Compare versions

Comparing version 9.1.1 to 10.0.0

CHANGELOG.md

 # Changelog
-All noteable changes to this project will be documented in this file.
+All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](http://keepachangelog.com/) and this project adheres to [Semantic Versioning](http://semver.org/).
 
-## Unrelased
+## [Unreleased]
+### Breaking
 ### Added
 ### Changed
 
+## [10.0.0] - 2017-07-04
+### Breaking
+- Print deprecation warning when metrics are constructed using non-objects
+- Print deprecation warning when `collectDefaultMetrics` is called with a number
+### Added
+- Ability to set default labels by registry
+- Allow passing in `registry` as second argument to `collectDefaultMetrics` to use that instead of the default registry
+### Changed
+- Convert code base to ES2015 code (node 4)
+  - add engines field to package.json
+  - Use object shorthand
+  - Remove `util-extend` in favor of `Object.assign`
+  - Arrow functions over binding or putting `this` in a variable
+  - Use template strings
+  - `prototype` -> `class`
+
+## [9.1.1] - 2017-06-17
+### Changed
+- Don't set timestamps for metrics that are never updated
+
 ## [9.1.0] - 2017-06-07
@@ -28,1 +49,8 @@ ### Added
 - Creating metrics with one argument per parameter - use object literals instead.
+
+
+[Unreleased]: https://github.com/siimon/prom-client/compare/v10.0.0...HEAD
+[10.0.0]: https://github.com/siimon/prom-client/compare/v9.1.1...v10.0.0
+[9.1.1]: https://github.com/siimon/prom-client/compare/v9.1.0...v9.1.1
+[9.1.0]: https://github.com/siimon/prom-client/compare/v9.0.0...v9.1.0
+[9.0.0]: https://github.com/siimon/prom-client/commit/1ef835f908e1a5032f228bbc754479fe7ccf5201

index.d.ts

@@ -11,11 +11,14 @@ // Type definitions for prom-client
 	 */
-	metrics(): string
+	metrics(): string;
+
 	/**
 	 * Remove all metrics from the registry
 	 */
-	clear(): void
+	clear(): void;
+
 	/**
 	 * Get all metrics as objects
 	 */
-	getMetricsAsJSON(): metric[]
+	getMetricsAsJSON(): metric[];
+
 	/**
@@ -25,3 +28,4 @@ * Remove a single metric
 	 */
-	removeSingleMetric(name: string): void
+	removeSingleMetric(name: string): void;
+
 	/**
@@ -31,13 +35,22 @@ * Get a single metric
 	 */
-	getSingleMetric(name:string): Metric
+	getSingleMetric(name: string): Metric;
+
 	/**
+	 * Set static labels to every metric emitted by this registry
+	 * @param object of name/value pairs:
+	 * { defaultLabel: "value", anotherLabel: "value 2" }
+	 */
+	setDefaultLabels(labels: Object): void;
+
+	/**
 	 * Get a string representation of a single metric by name
 	 * @param name The name of the metric
 	 */
-	getSingleMetricAsString(name:string): string
+	getSingleMetricAsString(name: string): string;
+
 	/**
-	* Merge registers
-	* @param registers The registers you want to merge together
-	*/
-	merge(registers: Registry[]): Registry
+	 * Merge registers
+	 * @param registers The registers you want to merge together
+	 */
+	static merge(registers: Registry[]): Registry;
 }
@@ -48,8 +61,8 @@
  */
-export const register: Registry
+export const register: Registry;
 
 /**
-* General metric type
-*/
-export type Metric = Counter | Gauge | Summary | Histogram
+ * General metric type
+ */
+export type Metric = Counter | Gauge | Summary | Histogram;
 
@@ -64,15 +77,16 @@ export enum MetricType {
 interface metric {
-	name: string,
-	help: string,
-	type: MetricType
+	name: string;
+	help: string;
+	type: MetricType;
 }
+
 interface labelValues {
-	[key: string]: string|number
+	[key: string]: string | number;
 }
 
 export interface CounterConfiguration {
-	name: string,
-	help: string,
-	labelNames?: string [],
-	registers?: Registry[]
+	name: string;
+	help: string;
+	labelNames?: string[];
+	registers?: Registry[];
 }
@@ -84,7 +98,6 @@
 export class Counter {
-
 	/**
 	 * @param configuration Configuration when creating a Counter metric. Name and Help is required.
 	 */
-	constructor(configuration: CounterConfiguration)
+	constructor(configuration: CounterConfiguration);
 
@@ -95,4 +108,5 @@ /**
 	 * @param labels Label keys
+	 * @deprecated
 	 */
-	constructor(name: string, help: string, labels?: string[])
+	constructor(name: string, help: string, labels?: string[]);
 
@@ -105,3 +119,3 @@ /**
 	 */
-	inc(labels: labelValues, value?: number, timestamp?: number|Date): void
+	inc(labels: labelValues, value?: number, timestamp?: number | Date): void;
 
@@ -113,3 +127,3 @@ /**
 	 */
-	inc(value?: number, timestamp?: number|Date): void
+	inc(value?: number, timestamp?: number | Date): void;
 
@@ -121,6 +135,5 @@ /**
 	 */
-	labels(...values: string[]): Counter.Internal
+	labels(...values: string[]): Counter.Internal;
 }
 
-
 export namespace Counter {
@@ -133,23 +146,21 @@ interface Internal {
 		 */
-		inc(value?: number, timestamp?: number|Date): void
+		inc(value?: number, timestamp?: number | Date): void;
 	}
-
 }
 
-export interface GaugeConfiguration{
-	name: string,
-	help: string,
-	labelNames?: string[],
-	registers?: Registry[]
+export interface GaugeConfiguration {
+	name: string;
+	help: string;
+	labelNames?: string[];
+	registers?: Registry[];
 }
 
 /**
-	A gauge is a metric that represents a single numerical value that can arbitrarily go up and down.
-*/
+ * A gauge is a metric that represents a single numerical value that can arbitrarily go up and down.
+ */
 export class Gauge {
-
 	/**
 	 * @param configuration Configuration when creating a Gauge metric. Name and Help is mandatory
 	 */
-	constructor(configuration: GaugeConfiguration)
+	constructor(configuration: GaugeConfiguration);
 
@@ -160,4 +171,5 @@ /**
 	 * @param labels Label keys
+	 * @deprecated
 	 */
-	constructor(name: string, help: string, labels?: string[])
+	constructor(name: string, help: string, labels?: string[]);
 
@@ -170,3 +182,3 @@ /**
 	 */
-	inc(labels: labelValues, value?: number, timestamp?: number|Date): void
+	inc(labels: labelValues, value?: number, timestamp?: number | Date): void;
 
@@ -178,3 +190,3 @@ /**
 	 */
-	inc(value?: number, timestamp?: number|Date): void
+	inc(value?: number, timestamp?: number | Date): void;
 
@@ -187,3 +199,3 @@ /**
 	 */
-	dec(labels: labelValues, value?: number, timestamp?: number|Date): void
+	dec(labels: labelValues, value?: number, timestamp?: number | Date): void;
 
@@ -195,5 +207,4 @@ /**
 	 */
-	dec(value?: number, timestamp?: number|Date): void
+	dec(value?: number, timestamp?: number | Date): void;
 
-
 	/**
@@ -205,3 +216,3 @@ * Set gauge value for labels
 	 */
-	set(labels: labelValues, value: number, timestamp?: number|Date): void
+	set(labels: labelValues, value: number, timestamp?: number | Date): void;
 
@@ -213,3 +224,3 @@ /**
 	 */
-	set(value: number, timestamp?: number|Date): void
+	set(value: number, timestamp?: number | Date): void;
 
@@ -220,3 +231,3 @@ /**
 	 */
-	setToCurrentTime(labels?: labelValues): void
+	setToCurrentTime(labels?: labelValues): void;
 
@@ -228,3 +239,3 @@ /**
 	 */
-	startTimer(labels?: labelValues): (labels?: labelValues) => void
+	startTimer(labels?: labelValues): (labels?: labelValues) => void;
 
@@ -236,3 +247,3 @@ /**
 	 */
-	labels(...values: string[]): Gauge.Internal
+	labels(...values: string[]): Gauge.Internal;
 }
@@ -247,3 +258,3 @@
 		 */
-		inc(value?: number, timestamp?: number|Date): void
+		inc(value?: number, timestamp?: number | Date): void;
 
@@ -255,3 +266,3 @@ /**
 		 */
-		dec(value?: number, timestamp?: number|Date): void
+		dec(value?: number, timestamp?: number | Date): void;
 
@@ -263,8 +274,8 @@ /**
 		 */
-		set(value: number, timestamp?: number|Date): void
+		set(value: number, timestamp?: number | Date): void;
 
 		/**
-	 	 * Set gauge value to current epoch time in ms
+		 * Set gauge value to current epoch time in ms
 		 */
-		setToCurrentTime(): void
+		setToCurrentTime(): void;
 
@@ -275,3 +286,3 @@ /**
 		 */
-		startTimer(): (labels?: labelValues) => void
+		startTimer(): (labels?: labelValues) => void;
 	}
@@ -281,7 +292,7 @@ }
 export interface HistogramConfiguration {
-	name: string,
-	help: string,
-	labelNames?: string[],
-	buckets?: number[],
-	registers?: Registry[]
+	name: string;
+	help: string;
+	labelNames?: string[];
+	buckets?: number[];
+	registers?: Registry[];
 }
@@ -293,7 +304,6 @@
 export class Histogram {
-
 	/**
 	 * @param configuration Configuration when creating the Histogram. Name and Help is mandatory
 	 */
-	constructor(configuration: HistogramConfiguration)
+	constructor(configuration: HistogramConfiguration);
 
@@ -306,3 +316,8 @@ /**
 	 */
-	constructor(name: string, help: string, labels?: string[], config?: Histogram.Config)
+	constructor(
+		name: string,
+		help: string,
+		labels?: string[],
+		config?: Histogram.Config
+	);
 	/**
@@ -312,4 +327,5 @@ * @param name The name of metric
 	 * @param config Configuration object for Histograms
+	 * @deprecated
 	 */
-	constructor(name: string, help: string, config: Histogram.Config)
+	constructor(name: string, help: string, config: Histogram.Config);
 
@@ -320,3 +336,3 @@ /**
 	 */
-	observe(value: number): void
+	observe(value: number): void;
 	/**
@@ -327,3 +343,4 @@ * Observe value for given labels
 	 */
-	observe(labels: labelValues, value: number): void
+	observe(labels: labelValues, value: number): void;
+
 	/**
@@ -334,7 +351,9 @@ * Start a timer where the value in seconds will observed
 	 */
-	startTimer(labels?: labelValues): (labels?: labelValues) => void
+	startTimer(labels?: labelValues): (labels?: labelValues) => void;
+
 	/**
 	 * Reset histogram values
 	 */
-	reset(): void
+	reset(): void;
+
 	/**
@@ -345,3 +364,3 @@ * Return the child for given labels
 	 */
-	labels(...values: string[]): Histogram.Internal
+	labels(...values: string[]): Histogram.Internal;
 }
@@ -355,3 +374,4 @@
 		 */
-		observe(value: number): void
+		observe(value: number): void;
+
 		/**
@@ -362,3 +382,3 @@ * Start a timer where the value in seconds will observed
 		 */
-		startTimer(): (labels?: labelValues) => void
+		startTimer(): (labels?: labelValues) => void;
 	}
@@ -370,12 +390,12 @@
 		 */
-		buckets?: number[]
+		buckets?: number[];
 	}
 }
 
-export interface SummaryConfiguration{
-	name: string,
-	help: string,
-	labelNames?: string[]
-	percentiles?: number[],
-	registers?: Registry[]
+export interface SummaryConfiguration {
+	name: string;
+	help: string;
+	labelNames?: string[];
+	percentiles?: number[];
+	registers?: Registry[];
 }
@@ -387,7 +407,6 @@
 export class Summary {
-
 	/**
 	 * @param configuration Configuration when creating Summary metric. Name and Help is mandatory
 	 */
-	constructor(configuration: SummaryConfiguration)
+	constructor(configuration: SummaryConfiguration);
 
@@ -400,3 +419,8 @@ /**
 	 */
-	constructor(name: string, help: string, labels?: string[], config?: Summary.Config)
+	constructor(
+		name: string,
+		help: string,
+		labels?: string[],
+		config?: Summary.Config
+	);
 	/**
@@ -406,4 +430,5 @@ * @param name The name of the metric
 	 * @param config Configuration object
+	 * @deprecated
 	 */
-	constructor(name: string, help: string, config: Summary.Config)
+	constructor(name: string, help: string, config: Summary.Config);
 
@@ -414,3 +439,3 @@ /**
 	 */
-	observe(value: number): void
+	observe(value: number): void;
 	/**
@@ -421,3 +446,4 @@ * Observe value for given labels
 	 */
-	observe(labels: labelValues, value: number): void
+	observe(labels: labelValues, value: number): void;
+
 	/**
@@ -428,7 +454,8 @@ * Start a timer where the value in seconds will observed
 	 */
-	startTimer(labels?: labelValues): (labels?: labelValues) => void
+	startTimer(labels?: labelValues): (labels?: labelValues) => void;
+
 	/**
 	 * Reset all values in the summary
 	 */
-	reset(): void
+	reset(): void;
 
@@ -440,3 +467,3 @@ /**
 	 */
-	labels(...values: string[]): Summary.Internal
+	labels(...values: string[]): Summary.Internal;
 }
@@ -450,3 +477,4 @@
 		 */
-		observe(value: number): void
+		observe(value: number): void;
+
 		/**
@@ -457,3 +485,3 @@ * Start a timer where the value in seconds will observed
 		 */
-		startTimer(): (labels?: labelValues) => void
+		startTimer(): (labels?: labelValues) => void;
 	}
@@ -465,3 +493,3 @@
 		 */
-		percentiles?: number[]
+		percentiles?: number[];
 	}
@@ -479,3 +507,3 @@ }
 	 */
-	constructor(url: string, options?: any, registry?: Registry)
+	constructor(url: string, options?: any, registry?: Registry);
 
@@ -487,3 +515,7 @@ /**
 	 */
-	pushAdd(params: Pushgateway.Parameters, callback: (error?: Error, httpResponse?: any, body?: any) => void): void;
+	pushAdd(
+		params: Pushgateway.Parameters,
+		callback: (error?: Error, httpResponse?: any, body?: any) => void
+	): void;
+
 	/**
@@ -494,3 +526,7 @@ * Overwrite all metric (using PUT to Pushgateway)
 	 */
-	push(params: Pushgateway.Parameters, callback: (error?: Error, httpResponse?: any, body?: any) => void): void;
+	push(
+		params: Pushgateway.Parameters,
+		callback: (error?: Error, httpResponse?: any, body?: any) => void
+	): void;
+
 	/**
@@ -501,3 +537,6 @@ * Delete all metrics for jobName
 	 */
-	delete(params: Pushgateway.Parameters, callback: (error?: Error, httpResponse?: any, body?: any) => void): void;
+	delete(
+		params: Pushgateway.Parameters,
+		callback: (error?: Error, httpResponse?: any, body?: any) => void
+	): void;
 }
@@ -510,3 +549,3 @@
 		 */
-		jobName: string,
+		jobName: string;
 		/**
@@ -516,4 +555,4 @@ * Label sets used in the url when making a request to the Pushgateway,
 		groupings?: {
-			[key: string]: string
-		}
+			[key: string]: string;
+		};
 	}
@@ -529,3 +568,8 @@ }
  */
-export function linearBuckets(start: number, width: number, count: number): number[]
+export function linearBuckets(
+	start: number,
+	width: number,
+	count: number
+): number[];
+
 /**
@@ -538,15 +582,29 @@ * Create an array that grows exponentially
  */
-export function exponentialBuckets(start: number, factor: number, count: number): number[]
+export function exponentialBuckets(
+	start: number,
+	factor: number,
+	count: number
+): number[];
+
+export interface DefaultMetricsCollectorConfiguration {
+	interval?: number;
+	registry?: Registry;
+}
+
 /**
  * Configure default metrics
- * @param interval The interval how often the default metrics should be probed
+ * @param config Configuration object for default metrics collector
  * @return The setInterval number
  */
-export function collectDefaultMetrics(interval: number): number
+export function collectDefaultMetrics(
+	config?: DefaultMetricsCollectorConfiguration
+): number;
 
 /**
  * Configure default metrics
+ * @param interval The interval how often the default metrics should be probed
+ * @deprecated
  * @return The setInterval number
  */
-export function collectDefaultMetrics(): number
+export function collectDefaultMetrics(interval: number): number;
 
@@ -557,3 +615,3 @@ export interface defaultMetrics {
 	 */
-	metricsList: string[]
+	metricsList: string[];
 }

index.js

@@ -8,5 +8,5 @@ /**
 
-exports.register = require('./lib/register');
+exports.register = require('./lib/registry').globalRegistry;
 exports.Registry = require('./lib/registry');
-exports.contentType = require('./lib/register').contentType;
+exports.contentType = require('./lib/registry').globalRegistry.contentType;
 
@@ -13,0 +13,0 @@ exports.Counter = require('./lib/counter');

lib/bucketGenerators.js

 'use strict';
 
-exports.linearBuckets = function(start, width, count) {
-	if(count < 1) {
+exports.linearBuckets = (start, width, count) => {
+	if (count < 1) {
 		throw new Error('Linear buckets needs a positive count');
 	}
 
-	var buckets = new Array(count);
-	for(var i = 0; i < count; i++) {
+	const buckets = new Array(count);
+	for (let i = 0; i < count; i++) {
 		buckets[i] = start;
@@ -16,14 +16,14 @@ start += width;
 
-exports.exponentialBuckets = function(start, factor, count) {
-	if(start <= 0) {
+exports.exponentialBuckets = (start, factor, count) => {
+	if (start <= 0) {
 		throw new Error('Exponential buckets needs a positive start');
 	}
-	if(count < 1) {
+	if (count < 1) {
 		throw new Error('Exponential buckets needs a positive count');
 	}
-	if(factor <= 1) {
+	if (factor <= 1) {
 		throw new Error('Exponential buckets needs a factor greater than 1');
 	}
-	var buckets = new Array(count);
-	for(var i = 0; i < count; i++) {
+	const buckets = new Array(count);
+	for (let i = 0; i < count; i++) {
 		buckets[i] = start;
@@ -30,0 +30,0 @@ start *= factor;

lib/counter.js

@@ -5,118 +5,124 @@ /**
 'use strict';
-var globalRegistry = require('./register');
-var type = 'counter';
-var isNumber = require('./util').isNumber;
-var isDate = require('./util').isDate;
-var getProperties = require('./util').getPropertiesFromObj;
-var hashObject = require('./util').hashObject;
-var validateLabels = require('./validation').validateLabel;
-var validateMetricName = require('./validation').validateMetricName;
-var validateLabelNames = require('./validation').validateLabelName;
-var isObject = require('./util').isObject;
-var extend = require('util-extend');
+const globalRegistry = require('./registry').globalRegistry;
+const type = 'counter';
+const isNumber = require('./util').isNumber;
+const isDate = require('./util').isDate;
+const getProperties = require('./util').getPropertiesFromObj;
+const hashObject = require('./util').hashObject;
+const validateLabels = require('./validation').validateLabel;
+const validateMetricName = require('./validation').validateMetricName;
+const validateLabelNames = require('./validation').validateLabelName;
+const isObject = require('./util').isObject;
+const printDeprecationObjectConstructor = require('./util')
+	.printDeprecationObjectConstructor;
 
-var getLabels = require('./util').getLabels;
+const getLabels = require('./util').getLabels;
 
-/**
- * Counter
- * @param {string} name - Name of the metric
- * @param {string} help - Help description for the metric
- * @param {Array.<string>} labels - Labels
- * @constructor
- */
-function Counter(name, help, labels) {
-	var config;
-	if(isObject(name)) {
-		config = extend({
-			labelNames: [],
-			registers: [ globalRegistry ]
-		}, name);
-	} else {
-		//Backwards compability - will be depricated
-		config = {
-			name: name,
-			help: help,
-			labelNames: labels,
-			registers: [ globalRegistry ]
-		};
-	}
+class Counter {
+	/**
+	 * Counter
+	 * @param {string} name - Name of the metric
+	 * @param {string} help - Help description for the metric
+	 * @param {Array.<string>} labels - Labels
+	 */
+	constructor(name, help, labels) {
+		let config;
+		if (isObject(name)) {
+			config = Object.assign(
+				{
+					labelNames: []
+				},
+				name
+			);
 
-	if(!config.help) {
-		throw new Error('Missing mandatory help parameter');
-	}
-	if(!config.name) {
-		throw new Error('Missing mandatory name parameter');
-	}
-	if(!validateMetricName(config.name)) {
-		throw new Error('Invalid metric name');
-	}
+			if (!config.registers) {
+				config.registers = [globalRegistry];
+			}
+		} else {
+			printDeprecationObjectConstructor();
 
-	if(!validateLabelNames(config.labelNames)) {
-		throw new Error('Invalid label name');
-	}
+			config = {
+				name,
+				help,
+				labelNames: labels,
+				registers: [globalRegistry]
+			};
+		}
 
-	this.name = name;
-	this.name = config.name;
-	this.hashMap = {};
+		if (!config.help) {
+			throw new Error('Missing mandatory help parameter');
+		}
+		if (!config.name) {
+			throw new Error('Missing mandatory name parameter');
+		}
+		if (!validateMetricName(config.name)) {
+			throw new Error('Invalid metric name');
+		}
 
-	this.labelNames = (config.labelNames || []);
+		if (!validateLabelNames(config.labelNames)) {
+			throw new Error('Invalid label name');
+		}
 
-	this.help = config.help;
+		this.name = config.name;
+		this.hashMap = {};
 
-	var metric = this;
-	config.registers.forEach(function(registryInstance) {
-		registryInstance.registerMetric(metric);
-	});
-}
+		this.labelNames = config.labelNames || [];
 
-/**
- * Increment counter
- * @param {object} labels - What label you want to be incremented
- * @param {Number} value - Value to increment, if omitted increment with 1
- * @param {(Number|Date)} timestamp - Timestamp to set the counter to
- * @returns {void}
- */
-Counter.prototype.inc = function(labels, value, timestamp) {
-	if(isNumber(labels) || !labels) {
-		return inc.call(this, null)(labels, value);
+		this.help = config.help;
+
+		config.registers.forEach(registryInstance =>
+			registryInstance.registerMetric(this)
+		);
 	}
 
-	var hash = hashObject(labels);
-	return inc.call(this, labels, hash)(value, timestamp);
-};
+	/**
+	 * Increment counter
+	 * @param {object} labels - What label you want to be incremented
+	 * @param {Number} value - Value to increment, if omitted increment with 1
+	 * @param {(Number|Date)} timestamp - Timestamp to set the counter to
+	 * @returns {void}
+	 */
+	inc(labels, value, timestamp) {
+		if (isNumber(labels) || !labels) {
+			return inc.call(this, null)(labels, value);
+		}
 
-Counter.prototype.get = function() {
-	return {
-		help: this.help,
-		name: this.name,
-		type: type,
-		values: getProperties(this.hashMap)
-	};
-};
+		const hash = hashObject(labels);
+		return inc.call(this, labels, hash)(value, timestamp);
+	}
 
-Counter.prototype.labels = function() {
-	var labels = getLabels(this.labelNames, arguments) || {};
-	var hash = hashObject(labels);
-	validateLabels(this.labelNames, labels);
-	return {
-		inc: inc.call(this, labels, hash)
-	};
-};
+	get() {
+		return {
+			help: this.help,
+			name: this.name,
+			type,
+			values: getProperties(this.hashMap)
+		};
+	}
 
-var inc = function(labels, hash) {
-	var that = this;
-	return function(value, timestamp) {
-		if(value && !isNumber(value)) {
+	labels() {
+		const labels = getLabels(this.labelNames, arguments) || {};
+		const hash = hashObject(labels);
+		validateLabels(this.labelNames, labels);
+		return {
+			inc: inc.call(this, labels, hash)
+		};
+	}
+}
+
+const inc = function(labels, hash) {
+	return (value, timestamp) => {
+		if (value && !isNumber(value)) {
 			throw new Error('Value is not a valid number', value);
 		}
-		if(timestamp && !isDate(timestamp) && !isNumber(timestamp)) {
+		if (timestamp && !isDate(timestamp) && !isNumber(timestamp)) {
 			throw new Error('Timestamp is not a valid date or number', value);
 		}
-		if(value < 0) {
+		if (value < 0) {
 			throw new Error('It is not possible to decrease a counter');
 		}
 
-		var incValue = value === null || value === undefined ? 1 : value;
+		const incValue = value === null || value === undefined ? 1 : value;
 
-		that.hashMap = createValue(that.hashMap, incValue, timestamp, labels, hash);
+		this.hashMap = createValue(this.hashMap, incValue, timestamp, labels, hash);
 	};
@@ -126,12 +132,14 @@ };
 function createValue(hashMap, value, timestamp, labels, hash) {
-	timestamp = isDate(timestamp) ? timestamp.valueOf() : isNumber(timestamp) ? timestamp : undefined;
-	if(hashMap[hash]) {
+	timestamp = isDate(timestamp)
+		? timestamp.valueOf()
+		: isNumber(timestamp) ? timestamp : undefined;
+	if (hashMap[hash]) {
 		hashMap[hash].value += value;
 		hashMap[hash].timestamp = timestamp;
 	} else {
-		hashMap[hash] = { value: value, labels: labels || {}, timestamp: timestamp };
+		hashMap[hash] = { value, labels: labels || {}, timestamp };
 	}
 	return hashMap;
-};
+}
 
 module.exports = Counter;

lib/defaultMetrics.js

 'use strict';
 
-var processCpuTotal = require('./metrics/processCpuTotal');
-var processStartTime = require('./metrics/processStartTime');
-var osMemoryHeap = require('./metrics/osMemoryHeap');
-var processOpenFileDescriptors = require('./metrics/processOpenFileDescriptors');
-var processMaxFileDescriptors = require('./metrics/processMaxFileDescriptors');
-var eventLoopLag = require('./metrics/eventLoopLag');
-var processHandles = require('./metrics/processHandles');
-var processRequests = require('./metrics/processRequests');
-var heapSizeAndUsed = require('./metrics/heapSizeAndUsed');
-var heapSpacesSizeAndUsed = require('./metrics/heapSpacesSizeAndUsed');
-var version = require('./metrics/version');
-var register = require('./register');
+const processCpuTotal = require('./metrics/processCpuTotal');
+const processStartTime = require('./metrics/processStartTime');
+const osMemoryHeap = require('./metrics/osMemoryHeap');
+const processOpenFileDescriptors = require('./metrics/processOpenFileDescriptors');
+const processMaxFileDescriptors = require('./metrics/processMaxFileDescriptors');
+const eventLoopLag = require('./metrics/eventLoopLag');
+const processHandles = require('./metrics/processHandles');
+const processRequests = require('./metrics/processRequests');
+const heapSizeAndUsed = require('./metrics/heapSizeAndUsed');
+const heapSpacesSizeAndUsed = require('./metrics/heapSpacesSizeAndUsed');
+const version = require('./metrics/version');
+const globalRegistry = require('./registry').globalRegistry;
+const printDeprecationCollectDefaultMetricsNumber = require('./util')
+	.printDeprecationCollectDefaultMetricsNumber;
 
-var metrics = {
-	processCpuTotal: processCpuTotal,
-	processStartTime: processStartTime,
-	osMemoryHeap: osMemoryHeap,
-	processOpenFileDescriptors: processOpenFileDescriptors,
-	processMaxFileDescriptors: processMaxFileDescriptors,
-	eventLoopLag: eventLoopLag,
-	processHandles: processHandles,
-	processRequests: processRequests,
-	heapSizeAndUsed: heapSizeAndUsed,
-	heapSpacesSizeAndUsed: heapSpacesSizeAndUsed,
-	version: version
+const metrics = {
+	processCpuTotal,
+	processStartTime,
+	osMemoryHeap,
+	processOpenFileDescriptors,
+	processMaxFileDescriptors,
+	eventLoopLag,
+	processHandles,
+	processRequests,
+	heapSizeAndUsed,
+	heapSpacesSizeAndUsed,
+	version
 };
-var metricsList = Object.keys(metrics);
+const metricsList = Object.keys(metrics);
 
-var existingInterval = null;
+let existingInterval = null;
 // This is used to ensure the program throws on duplicate metrics during first run
 // We might want to consider not supporting running the default metrics function more than once
-var init = true;
+let init = true;
 
-module.exports = function startDefaultMetrics(interval) {
-	if(existingInterval !== null) {
+module.exports = function startDefaultMetrics(config) {
+	let normalizedConfig = config;
+	if (typeof config === 'number') {
+		printDeprecationCollectDefaultMetricsNumber(config);
+
+		normalizedConfig = { timeout: config };
+	}
+
+	normalizedConfig = Object.assign({ timeout: 10000 }, normalizedConfig);
+
+	if (existingInterval !== null) {
 		clearInterval(existingInterval);
 	}
 
-	interval = interval || 10000;
+	const initialisedMetrics = metricsList.map(metric => {
+		const defaultMetric = metrics[metric];
+		if (!init) {
+			defaultMetric.metricNames.map(
+				globalRegistry.removeSingleMetric,
+				globalRegistry
+			);
+		}
 
-	var initialisedMetrics = metricsList
-		.map(function(metric) {
-			var defaultMetric = metrics[metric];
-			if(!init) {
-				defaultMetric.metricNames.map(register.removeSingleMetric, register);
-			}
+		return defaultMetric(normalizedConfig.register);
+	});
 
-			return defaultMetric();
-		});
-
 	function updateAllMetrics() {
-		initialisedMetrics.forEach(function(metric) {
-			metric.call();
-		});
+		initialisedMetrics.forEach(metric => metric.call());
 	}
@@ -61,3 +70,6 @@
 
-	existingInterval = setInterval(updateAllMetrics, interval).unref();
+	existingInterval = setInterval(
+		updateAllMetrics,
+		normalizedConfig.interval
+	).unref();
 
@@ -64,0 +76,0 @@ init = false;

lib/gauge.js

@@ -6,80 +6,86 @@ /**
 
-var globalRegistry = require('./register');
-var type = 'gauge';
+const globalRegistry = require('./registry').globalRegistry;
+const type = 'gauge';
 
-var isNumber = require('./util').isNumber;
-var isDate = require('./util').isDate;
-var extend = require('util-extend');
-var createValue = require('./util').setValue;
-var getProperties = require('./util').getPropertiesFromObj;
-var getLabels = require('./util').getLabels;
-var hashObject = require('./util').hashObject;
-var validateMetricName = require('./validation').validateMetricName;
-var validateLabels = require('./validation').validateLabel;
-var validateLabelNames = require('./validation').validateLabelName;
-var isObject = require('./util').isObject;
-var extend = require('util-extend');
+const isNumber = require('./util').isNumber;
+const isDate = require('./util').isDate;
+const createValue = require('./util').setValue;
+const getProperties = require('./util').getPropertiesFromObj;
+const getLabels = require('./util').getLabels;
+const hashObject = require('./util').hashObject;
+const validateMetricName = require('./validation').validateMetricName;
+const validateLabels = require('./validation').validateLabel;
+const validateLabelNames = require('./validation').validateLabelName;
+const isObject = require('./util').isObject;
+const printDeprecationObjectConstructor = require('./util')
+	.printDeprecationObjectConstructor;
 
-/**
- * Gauge constructor
- * @param {string} name - Name of the metric
- * @param {string} help - Help for the metric
- * @param {Array.<string>} labels - Array with strings, all label keywords supported
- * @constructor
- */
-function Gauge(name, help, labels) {
-	var config;
-	if(isObject(name)) {
-		config = extend({
-			labelNames: [],
-			registers: [ globalRegistry ],
-		}, name);
-	} else {
-		config = {
-			name: name,
-			help: help,
-			labelNames: labels,
-			registers: [ globalRegistry ]
-		};
-	}
+class Gauge {
+	/**
+	 * Gauge
+	 * @param {string} name - Name of the metric
+	 * @param {string} help - Help for the metric
+	 * @param {Array.<string>} labels - Array with strings, all label keywords supported
+	 */
+	constructor(name, help, labels) {
+		let config;
+		if (isObject(name)) {
+			config = Object.assign(
+				{
+					labelNames: []
+				},
+				name
+			);
 
-	if(!config.help) {
-		throw new Error('Missing mandatory help parameter');
-	}
-	if(!config.name) {
-		throw new Error('Missing mandatory name parameter');
-	}
-	if(!validateMetricName(config.name)) {
-		throw new Error('Invalid metric name');
-	}
-	if(!validateLabelNames(config.labelNames)) {
-		throw new Error('Invalid label name');
-	}
+			if (!config.registers) {
+				config.registers = [globalRegistry];
+			}
+		} else {
+			printDeprecationObjectConstructor();
+			config = {
+				name,
+				help,
+				labelNames: labels,
+				registers: [globalRegistry]
+			};
+		}
 
-	this.name = config.name;
-	this.labelNames = config.labelNames || [];
-	this.hashMap = {};
-	this.help = config.help;
+		if (!config.help) {
+			throw new Error('Missing mandatory help parameter');
+		}
+		if (!config.name) {
+			throw new Error('Missing mandatory name parameter');
+		}
+		if (!validateMetricName(config.name)) {
+			throw new Error('Invalid metric name');
+		}
+		if (!validateLabelNames(config.labelNames)) {
+			throw new Error('Invalid label name');
+		}
 
-	var metric = this;
-	config.registers.forEach(function(registryInstance) {
-		registryInstance.registerMetric(metric);
-	});
-}
+		this.name = config.name;
+		this.labelNames = config.labelNames || [];
+		this.hashMap = {};
+		this.help = config.help;
 
-/**
- * Set a gauge to a value
- * @param {object} labels - Object with labels and their values
- * @param {Number} value - Value to set the gauge to, must be positive
- * @param {(Number|Date)} timestamp - Timestamp to set the gauge to
- * @returns {void}
- */
-Gauge.prototype.set = function(labels, value, timestamp) {
-	if(isNumber(labels)) {
-		return set.call(this, null)(labels, value);
+		config.registers.forEach(registryInstance =>
+			registryInstance.registerMetric(this)
+		);
 	}
-	return set.call(this, labels)(value, timestamp);
-};
 
-/**
+	/**
+	 * Set a gauge to a value
+	 * @param {object} labels - Object with labels and their values
+	 * @param {Number} value - Value to set the gauge to, must be positive
+	 * @param {(Number|Date)} timestamp - Timestamp to set the gauge to
+	 * @returns {void}
+	 */
+	set(labels, value, timestamp) {
+		if (isNumber(labels)) {
+			return set.call(this, null)(labels, value);
+		}
+		return set.call(this, labels)(value, timestamp);
+	}
+
+	/**
  * Increment a gauge value
@@ -91,8 +97,8 @@ * @param {object} labels - Object with labels where key is the label key and value is label value. Can only be one level deep
  */
-Gauge.prototype.inc = function(labels, value, timestamp) {
-	inc.call(this, labels)(value, timestamp);
-};
+	inc(labels, value, timestamp) {
+		inc.call(this, labels)(value, timestamp);
+	}
 
+	/**
 
-/**
  * Decrement a gauge value
@@ -104,58 +110,58 @@ * @param {object} labels - Object with labels where key is the label key and value is label value. Can only be one level deep
  */
-Gauge.prototype.dec = function(labels, value, timestamp) {
-	dec.call(this, labels)(value, timestamp);
-};
+	dec(labels, value, timestamp) {
+		dec.call(this, labels)(value, timestamp);
+	}
 
-/**
- * Set the gauge to current unix epoch
- * @param {object} labels - Object with labels where key is the label key and value is label value. Can only be one level deep
- * @returns {void}
- */
-Gauge.prototype.setToCurrentTime = function(labels) {
-	return setToCurrentTime.call(this, labels)();
-};
+	/**
+	 * Set the gauge to current unix epoch
+	 * @param {object} labels - Object with labels where key is the label key and value is label value. Can only be one level deep
+	 * @returns {void}
+	 */
+	setToCurrentTime(labels) {
+		return setToCurrentTime.call(this, labels)();
+	}
 
-/**
- * Start a timer
- * @param {object} labels - Object with labels where key is the label key and value is label value. Can only be one level deep
- * @returns {function} - Invoke this function to set the duration in seconds since you started the timer.
- * @example
- * var done = gauge.startTimer();
- * makeXHRRequest(function(err, response) {
- *	done(); //Duration of the request will be saved
- * });
- */
-Gauge.prototype.startTimer = function(labels) {
-	return startTimer.call(this, labels)();
-};
+	/**
+	 * Start a timer
+	 * @param {object} labels - Object with labels where key is the label key and value is label value. Can only be one level deep
+	 * @returns {function} - Invoke this function to set the duration in seconds since you started the timer.
+	 * @example
+	 * var done = gauge.startTimer();
+	 * makeXHRRequest(function(err, response) {
+	 *	done(); //Duration of the request will be saved
+	 * });
+	 */
+	startTimer(labels) {
+		return startTimer.call(this, labels)();
+	}
 
-Gauge.prototype.get = function() {
-	return {
-		help: this.help,
-		name: this.name,
-		type: type,
-		values: getProperties(this.hashMap)
-	};
-};
+	get() {
+		return {
+			help: this.help,
+			name: this.name,
+			type,
+			values: getProperties(this.hashMap)
+		};
+	}
 
-Gauge.prototype._getValue = function(labels) {
-	var hash = hashObject(labels || {});
-	return this.hashMap[hash] ? this.hashMap[hash].value : 0;
-};
+	_getValue(labels) {
+		const hash = hashObject(labels || {});
+		return this.hashMap[hash] ? this.hashMap[hash].value : 0;
+	}
 
-Gauge.prototype.labels = function() {
-	var labels = getLabels(this.labelNames, arguments);
-	return {
-		inc: inc.call(this, labels),
-		dec: dec.call(this, labels),
-		set: set.call(this, labels),
-		setToCurrentTime: setToCurrentTime.call(this, labels),
-		startTimer: startTimer.call(this, labels)
-	};
-};
+	labels() {
+		const labels = getLabels(this.labelNames, arguments);
+		return {
+			inc: inc.call(this, labels),
+			dec: dec.call(this, labels),
+			set: set.call(this, labels),
+			setToCurrentTime: setToCurrentTime.call(this, labels),
+			startTimer: startTimer.call(this, labels)
+		};
+	}
+}
 
 function setToCurrentTime(labels) {
-	var gauge = this;
-	return function() {
-		gauge.set(labels, new Date().getTime());
+	return () => {
+		this.set(labels, Date.now());
 	};
@@ -165,8 +171,10 @@ }
 function startTimer(startLabels) {
-	var gauge = this;
-	return function() {
-		var start = process.hrtime();
-		return function(endLabels) {
-			var delta = process.hrtime(start);
-			gauge.set(extend(startLabels || {}, endLabels), delta[0] + delta[1] / 1e9);
+	return () => {
+		const start = process.hrtime();
+		return endLabels => {
+			const delta = process.hrtime(start);
+			this.set(
+				Object.assign(startLabels || {}, endLabels),
+				delta[0] + delta[1] / 1e9
+			);
 		};
@@ -177,6 +185,9 @@ };
 function dec(labels) {
-	var gauge = this;
-	return function(value, timestamp) {
-		var data = convertLabelsAndValues(labels, value);
-		gauge.set(data.labels, gauge._getValue(data.labels) - (data.value || 1), timestamp);
+	return (value, timestamp) => {
+		const data = convertLabelsAndValues(labels, value);
+		this.set(
+			data.labels,
+			this._getValue(data.labels) - (data.value || 1),
+			timestamp
+		);
 	};
@@ -186,6 +197,9 @@ }
 function inc(labels) {
-	var gauge = this;
-	return function(value, timestamp) {
-		var data = convertLabelsAndValues(labels, value);
-		gauge.set(data.labels, gauge._getValue(data.labels) + (data.value || 1), timestamp);
+	return (value, timestamp) => {
+		const data = convertLabelsAndValues(labels, value);
+		this.set(
+			data.labels,
+			this._getValue(data.labels) + (data.value || 1),
+			timestamp
+		);
 	};
@@ -195,8 +209,7 @@ }
 function set(labels) {
-	var that = this;
-	return function(value, timestamp) {
-		if(!isNumber(value)) {
+	return (value, timestamp) => {
+		if (!isNumber(value)) {
 			throw new Error('Value is not a valid number', value);
 		}
-		if(timestamp && !isDate(timestamp) && !isNumber(timestamp)) {
+		if (timestamp && !isDate(timestamp) && !isNumber(timestamp)) {
 			throw new Error('Timestamp is not a valid date or number', value);
@@ -207,4 +220,4 @@ }
 
-		validateLabels(that.labelNames, labels);
-		that.hashMap = createValue(that.hashMap, value, labels, timestamp);
+		validateLabels(this.labelNames, labels);
+		this.hashMap = createValue(this.hashMap, value, labels, timestamp);
 	};
@@ -214,3 +227,3 @@ }
 function convertLabelsAndValues(labels, value) {
-	if(isNumber(labels)) {
+	if (isNumber(labels)) {
 		return {
@@ -222,8 +235,7 @@ value: labels,
 	return {
-		labels: labels,
-		value: value
+		labels,
+		value
 	};
 }
 
-
 module.exports = Gauge;

lib/histogram.js

@@ -6,134 +6,145 @@ /**
 
-var globalRegistry = require('./register');
-var type = 'histogram';
-var isNumber = require('./util').isNumber;
-var extend = require('util-extend');
-var getProperties = require('./util').getPropertiesFromObj;
-var getLabels = require('./util').getLabels;
-var hashObject = require('./util').hashObject;
-var validateLabels = require('./validation').validateLabel;
-var validateMetricName = require('./validation').validateMetricName;
-var validateLabelNames = require('./validation').validateLabelName;
-var isObject = require('./util').isObject;
+const globalRegistry = require('./registry').globalRegistry;
+const type = 'histogram';
+const isNumber = require('./util').isNumber;
+const getProperties = require('./util').getPropertiesFromObj;
+const getLabels = require('./util').getLabels;
+const hashObject = require('./util').hashObject;
+const validateLabels = require('./validation').validateLabel;
+const validateMetricName = require('./validation').validateMetricName;
+const validateLabelNames = require('./validation').validateLabelName;
+const isObject = require('./util').isObject;
+const printDeprecationObjectConstructor = require('./util')
+	.printDeprecationObjectConstructor;
 
-/**
- * Histogram
- * @param {string} name - Name of the metric
- * @param {string} help - Help for the metric
- * @param {object|Array.<string>} labelsOrConf - Either array of label names or config object as a key-value object
- * @param {object} conf - Configuration object
- * @constructor
- */
-function Histogram(name, help, labelsOrConf, conf) {
-	var config;
+class Histogram {
+	/**
+	 * Histogram
+	 * @param {string} name - Name of the metric
+	 * @param {string} help - Help for the metric
+	 * @param {object|Array.<string>} labelsOrConf - Either array of label names or config object as a key-value object
+	 * @param {object} conf - Configuration object
+	 */
+	constructor(name, help, labelsOrConf, conf) {
+		let config;
 
-	if(isObject(name)) {
-		config = extend( {
-			buckets: [0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10],
-			labelNames: [],
-			registers: [ globalRegistry ],
-		}, name);
-	} else {
-		var obj;
-		var labels = [];
+		if (isObject(name)) {
+			config = Object.assign(
+				{
+					buckets: [0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10],
+					labelNames: []
+				},
+				name
+			);
 
-		if(Array.isArray(labelsOrConf)) {
-			obj = conf || {};
-			labels = labelsOrConf;
+			if (!config.registers) {
+				config.registers = [globalRegistry];
+			}
 		} else {
-			obj = labelsOrConf || {};
+			let obj;
+			let labels = [];
+
+			if (Array.isArray(labelsOrConf)) {
+				obj = conf || {};
+				labels = labelsOrConf;
+			} else {
+				obj = labelsOrConf || {};
+			}
+
+			printDeprecationObjectConstructor();
+
+			config = {
+				name,
+				labelNames: labels,
+				help,
+				buckets: configureUpperbounds(obj.buckets),
+				registers: [globalRegistry]
+			};
 		}
+		validateInput(config.name, config.help, config.labelNames);
 
-		config = {
-			name: name,
-			labelNames: labels,
-			help: help,
-			buckets: configureUpperbounds(obj.buckets),
-			registers: [ globalRegistry ]
-		};
-	}
-	validateInput(config.name, config.help, config.labelNames);
+		this.name = config.name;
+		this.help = config.help;
 
-	this.name = config.name;
-	this.help = config.help;
+		this.upperBounds = config.buckets;
+		this.bucketValues = this.upperBounds.reduce((acc, upperBound) => {
+			acc[upperBound] = 0;
+			return acc;
+		}, {});
 
-	this.upperBounds = config.buckets;
-	this.bucketValues = this.upperBounds.reduce(function(acc, upperBound) {
-		acc[upperBound] = 0;
-		return acc;
-	}, {});
+		Object.freeze(this.bucketValues);
+		Object.freeze(this.upperBounds);
+		this.sum = 0;
+		this.count = 0;
 
-	Object.freeze(this.bucketValues);
-	Object.freeze(this.upperBounds);
-	this.sum = 0;
-	this.count = 0;
+		this.hashMap = {};
+		this.labelNames = config.labelNames || [];
 
-	this.hashMap = {};
-	this.labelNames = config.labelNames || [];
+		config.registers.forEach(registryInstance =>
+			registryInstance.registerMetric(this)
+		);
+	}
 
-	var metric = this;
-	config.registers.forEach(function(registryInstance) {
-		registryInstance.registerMetric(metric);
-	});
-}
+	/**
+	 * Observe a value in histogram
+	 * @param {object} labels - Object with labels where key is the label key and value is label value. Can only be one level deep
+	 * @param {Number} value - Value to observe in the histogram
+	 * @returns {void}
+	 */
+	observe(labels, value) {
+		observe.call(this, labels === 0 ? 0 : labels || {})(value);
+	}
 
-/**
- * Observe a value in histogram
- * @param {object} labels - Object with labels where key is the label key and value is label value. Can only be one level deep
- * @param {Number} value - Value to observe in the histogram
- * @returns {void}
- */
-Histogram.prototype.observe = function(labels, value) {
-	observe.call(this, labels === 0 ? 0 : (labels || {}))(value);
-};
-
-Histogram.prototype.get = function() {
-	var data = getProperties(this.hashMap);
-	var values =
-		data.map(extractBucketValuesForExport(this))
+	get() {
+		const data = getProperties(this.hashMap);
+		const values = data
+			.map(extractBucketValuesForExport(this))
 			.reduce(addSumAndCountForExport(this), []);
 
-	return {
-		name: this.name,
-		help: this.help,
-		type: type,
-		values: values
-	};
-};
+		return {
+			name: this.name,
+			help: this.help,
+			type,
+			values
+		};
+	}
 
-Histogram.prototype.reset = function() {
-	this.sum = 0;
-	this.count = 0;
-	this.hashMap = {};
-};
+	reset() {
+		this.sum = 0;
+		this.count = 0;
+		this.hashMap = {};
+	}
 
-/**
- * Start a timer that could be used to logging durations
- * @param {object} labels - Object with labels where key is the label key and value is label value. Can only be one level deep
- * @returns {function} - Function to invoke when you want to stop the timer and observe the duration in seconds
- * @example
- * var end = histogram.startTimer();
- * makeExpensiveXHRRequest(function(err, res) {
- *	end(); //Observe the duration of expensiveXHRRequest
- * });
- */
-Histogram.prototype.startTimer = function(labels) {
-	return startTimer.call(this, labels)();
-};
+	/**
+	 * Start a timer that could be used to logging durations
+	 * @param {object} labels - Object with labels where key is the label key and value is label value. Can only be one level deep
+	 * @returns {function} - Function to invoke when you want to stop the timer and observe the duration in seconds
+	 * @example
+	 * var end = histogram.startTimer();
+	 * makeExpensiveXHRRequest(function(err, res) {
+     *	end(); //Observe the duration of expensiveXHRRequest
+     * });
+	 */
+	startTimer(labels) {
+		return startTimer.call(this, labels)();
+	}
 
-Histogram.prototype.labels = function() {
-	var labels = getLabels(this.labelNames, arguments);
-	return {
-		observe: observe.call(this, labels),
-		startTimer: startTimer.call(this, labels)
-	};
-};
+	labels() {
+		const labels = getLabels(this.labelNames, arguments);
+		return {
+			observe: observe.call(this, labels),
+			startTimer: startTimer.call(this, labels)
+		};
+	}
+}
 
 function startTimer(startLabels) {
-	var histogram = this;
-	return function() {
-		var start = process.hrtime();
-		return function(endLabels) {
-			var delta = process.hrtime(start);
-			histogram.observe(extend(startLabels || {}, endLabels),  delta[0] + delta[1] / 1e9);
+	return () => {
+		const start = process.hrtime();
+		return endLabels => {
+			const delta = process.hrtime(start);
+			this.observe(
+				Object.assign(startLabels || {}, endLabels),
+				delta[0] + delta[1] / 1e9
+			);
 		};
@@ -143,19 +154,19 @@ };
 function validateInput(name, help, labels) {
-	if(!help) {
+	if (!help) {
 		throw new Error('Missing mandatory help parameter');
 	}
-	if(!name) {
+	if (!name) {
 		throw new Error('Missing mandatory name parameter');
 	}
 
-	if(!validateMetricName(name)) {
+	if (!validateMetricName(name)) {
 		throw new Error('Invalid metric name');
 	}
 
-	if(!validateLabelNames(labels)) {
+	if (!validateLabelNames(labels)) {
 		throw new Error('Invalid label name');
 	}
 
-	labels.forEach(function(label) {
-		if(label === 'le') {
+	labels.forEach(label => {
+		if (label === 'le') {
 			throw new Error('le is a reserved label keyword');
@@ -167,4 +178,16 @@ }
 function configureUpperbounds(configuredBuckets) {
-	var defaultBuckets = [0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10];
-	return [].concat((configuredBuckets || defaultBuckets)).sort(sortAscending);
+	const defaultBuckets = [
+		0.005,
+		0.01,
+		0.025,
+		0.05,
+		0.1,
+		0.25,
+		0.5,
+		1,
+		2.5,
+		5,
+		10
+	];
+	return [].concat(configuredBuckets || defaultBuckets).sort(sortAscending);
 }
@@ -178,5 +201,5 @@
 	return {
-		labels: labels,
-		value: value,
-		metricName: metricName
+		labels,
+		value,
+		metricName
 	};
@@ -186,8 +209,7 @@ }
 function findBound(upperBounds, value) {
-	for(var i = 0; i < upperBounds.length; i++) {
-		var bound = upperBounds[i];
-		if(value <= bound) {
+	for (let i = 0; i < upperBounds.length; i++) {
+		const bound = upperBounds[i];
+		if (value <= bound) {
 			return bound;
 		}
-
 	}
@@ -198,18 +220,20 @@ return -1;
 function observe(labels) {
-	var histogram = this;
-	return function(value) {
-		var labelValuePair = convertLabelsAndValues(labels, value);
+	return value => {
+		const labelValuePair = convertLabelsAndValues(labels, value);
 
-		validateLabels(histogram.labelNames, labelValuePair.labels);
-		if(!isNumber(labelValuePair.value)) {
+		validateLabels(this.labelNames, labelValuePair.labels);
+		if (!isNumber(labelValuePair.value)) {
 			throw new Error('Value is not a valid number', labelValuePair.value);
 		}
 
-		var hash = hashObject(labelValuePair.labels);
-		var valueFromMap = histogram.hashMap[hash];
-		if(!valueFromMap) {
-			valueFromMap = createBaseValues(labelValuePair.labels, extend({}, histogram.bucketValues));
+		const hash = hashObject(labelValuePair.labels);
+		let valueFromMap = this.hashMap[hash];
+		if (!valueFromMap) {
+			valueFromMap = createBaseValues(
+				labelValuePair.labels,
+				Object.assign({}, this.bucketValues)
+			);
 		}
 
-		var b = findBound(histogram.upperBounds, labelValuePair.value);
+		const b = findBound(this.upperBounds, labelValuePair.value);
 
@@ -219,7 +243,7 @@ valueFromMap.sum += labelValuePair.value;
 
-		if(valueFromMap.bucketValues.hasOwnProperty(b)) {
+		if (valueFromMap.bucketValues.hasOwnProperty(b)) {
 			valueFromMap.bucketValues[b] += 1;
 		}
 
-		histogram.hashMap[hash] = valueFromMap;
+		this.hashMap[hash] = valueFromMap;
 	};
@@ -230,4 +254,4 @@ }
 	return {
-		labels: labels,
-		bucketValues: bucketValues,
+		labels,
+		bucketValues,
 		sum: 0,
@@ -239,3 +263,3 @@ count: 0
 function convertLabelsAndValues(labels, value) {
-	if(isNumber(labels)) {
+	if (isNumber(labels)) {
 		return {
@@ -247,4 +271,4 @@ value: labels,
 	return {
-		labels: labels,
-		value: value
+		labels,
+		value
 	};
@@ -254,5 +278,7 @@ }
 function extractBucketValuesForExport(histogram) {
-	return function(bucketData) {
-		var buckets = histogram.upperBounds.map(createBucketValues(bucketData, histogram));
-		return { buckets: buckets, data: bucketData };
+	return bucketData => {
+		const buckets = histogram.upperBounds.map(
+			createBucketValues(bucketData, histogram)
+		);
+		return { buckets, data: bucketData };
 	};
@@ -262,9 +288,15 @@ }
 function addSumAndCountForExport(histogram) {
-	return function(acc, d) {
+	return (acc, d) => {
 		acc = acc.concat(d.buckets);
 
-		var infLabel = extend({ le: '+Inf' }, d.data.labels);
-		acc.push(createValuePair(infLabel, d.data.count, histogram.name + '_bucket'));
-		acc.push(createValuePair(d.data.labels, d.data.sum, histogram.name + '_sum'));
-		acc.push(createValuePair(d.data.labels, d.data.count, histogram.name + '_count'));
+		const infLabel = Object.assign({ le: '+Inf' }, d.data.labels);
+		acc.push(
+			createValuePair(infLabel, d.data.count, `${histogram.name}_bucket`)
+		);
+		acc.push(
+			createValuePair(d.data.labels, d.data.sum, `${histogram.name}_sum`)
+		);
+		acc.push(
+			createValuePair(d.data.labels, d.data.count, `${histogram.name}_count`)
+		);
 		return acc;
@@ -275,7 +307,7 @@ };
 function createBucketValues(bucket, histogram) {
-	var acc = 0;
-	return function(upperBound) {
+	let acc = 0;
+	return upperBound => {
 		acc += bucket.bucketValues[upperBound];
-		var lbls = extend({ le: upperBound }, bucket.labels);
-		var valuePair = createValuePair(lbls, acc, histogram.name + '_bucket');
+		const lbls = Object.assign({ le: upperBound }, bucket.labels);
+		const valuePair = createValuePair(lbls, acc, `${histogram.name}_bucket`);
 		return valuePair;
@@ -282,0 +314,0 @@ };

lib/metrics/eventLoopLag.js

 'use strict';
 
-var Gauge = require('../gauge');
+const Gauge = require('../gauge');
 
-var NODEJS_EVENTLOOP_LAG = 'nodejs_eventloop_lag_seconds';
+const NODEJS_EVENTLOOP_LAG = 'nodejs_eventloop_lag_seconds';
 
 function reportEventloopLag(start, gauge) {
-	var delta = process.hrtime(start);
-	var nanosec = delta[0] * 1e9 + delta[1];
-	var seconds = nanosec / 1e9;
+	const delta = process.hrtime(start);
+	const nanosec = delta[0] * 1e9 + delta[1];
+	const seconds = nanosec / 1e9;
 
@@ -15,7 +15,11 @@ gauge.set(seconds, Date.now());
 
-module.exports = function() {
-	var gauge = new Gauge(NODEJS_EVENTLOOP_LAG, 'Lag of event loop in seconds.');
+module.exports = registry => {
+	const gauge = new Gauge({
+		name: NODEJS_EVENTLOOP_LAG,
+		help: 'Lag of event loop in seconds.',
+		registers: registry ? [registry] : undefined
+	});
 
-	return function() {
-		var start = process.hrtime();
+	return () => {
+		const start = process.hrtime();
 		setImmediate(reportEventloopLag, start, gauge);
@@ -22,0 +26,0 @@ };

lib/metrics/heapSizeAndUsed.js

 'use strict';
 
-var Gauge = require('../gauge');
-var safeMemoryUsage = require('./helpers/safeMemoryUsage');
+const Gauge = require('../gauge');
+const safeMemoryUsage = require('./helpers/safeMemoryUsage');
 
-var NODEJS_HEAP_SIZE_TOTAL = 'nodejs_heap_size_total_bytes';
-var NODEJS_HEAP_SIZE_USED = 'nodejs_heap_size_used_bytes';
-var NODEJS_EXTERNAL_MEMORY = 'nodejs_external_memory_bytes';
+const NODEJS_HEAP_SIZE_TOTAL = 'nodejs_heap_size_total_bytes';
+const NODEJS_HEAP_SIZE_USED = 'nodejs_heap_size_used_bytes';
+const NODEJS_EXTERNAL_MEMORY = 'nodejs_external_memory_bytes';
 
-module.exports = function() {
-	if(typeof process.memoryUsage !== 'function') {
-		return function() {
-		};
+module.exports = registry => {
+	if (typeof process.memoryUsage !== 'function') {
+		return () => {};
 	}
 
-	var heapSizeTotal = new Gauge(NODEJS_HEAP_SIZE_TOTAL, 'Process heap size from node.js in bytes.');
-	var heapSizeUsed = new Gauge(NODEJS_HEAP_SIZE_USED, 'Process heap size used from node.js in bytes.');
+	const registers = registry ? [registry] : undefined;
 
-	var usage = safeMemoryUsage();
-	if(usage && usage.external) {
-		var externalMemUsed = new Gauge(NODEJS_EXTERNAL_MEMORY, 'Nodejs external memory size in bytes.');
+	const heapSizeTotal = new Gauge({
+		name: NODEJS_HEAP_SIZE_TOTAL,
+		help: 'Process heap size from node.js in bytes.',
+		registers
+	});
+	const heapSizeUsed = new Gauge({
+		name: NODEJS_HEAP_SIZE_USED,
+		help: 'Process heap size used from node.js in bytes.',
+		registers
+	});
+	let externalMemUsed;
+
+	const usage = safeMemoryUsage();
+	if (usage && usage.external) {
+		externalMemUsed = new Gauge({
+			name: NODEJS_EXTERNAL_MEMORY,
+			help: 'Nodejs external memory size in bytes.',
+			registers
+		});
 	}
 
-	return function() {
-    	// process.memoryUsage() can throw EMFILE errors, see #67
-		var memUsage = safeMemoryUsage();
-		if(memUsage) {
-			var now = Date.now();
+	return () => {
+		// process.memoryUsage() can throw EMFILE errors, see #67
+		const memUsage = safeMemoryUsage();
+		if (memUsage) {
+			const now = Date.now();
 			heapSizeTotal.set(memUsage.heapTotal, now);
 			heapSizeUsed.set(memUsage.heapUsed, now);
-			if(memUsage.external && externalMemUsed) {
+			if (memUsage.external && externalMemUsed) {
 				externalMemUsed.set(memUsage.external, now);
@@ -36,6 +50,14 @@ }
 
-		return {total: heapSizeTotal, used: heapSizeUsed, external: externalMemUsed};
+		return {
+			total: heapSizeTotal,
+			used: heapSizeUsed,
+			external: externalMemUsed
+		};
 	};
 };
 
-module.exports.metricNames = [NODEJS_HEAP_SIZE_TOTAL, NODEJS_HEAP_SIZE_USED, NODEJS_EXTERNAL_MEMORY];
+module.exports.metricNames = [
+	NODEJS_HEAP_SIZE_TOTAL,
+	NODEJS_HEAP_SIZE_USED,
+	NODEJS_EXTERNAL_MEMORY
+];

lib/metrics/heapSpacesSizeAndUsed.js

 'use strict';
 
-var Gauge = require('../gauge');
-var v8;
+const Gauge = require('../gauge');
+let v8;
 
@@ -9,37 +9,37 @@ try {
 } catch (e) {
-  // node version is too old
-  // probably we can use v8-heap-space-statistics for >=node-4.0.0 and <node-6.0.0
+	// node version is too old
+	// probably we can use v8-heap-space-statistics for >=node-4.0.0 and <node-6.0.0
 }
 
-var METRICS = [
-	'total',
-	'used',
-	'available'
-];
+const METRICS = ['total', 'used', 'available'];
 
-var NODEJS_HEAP_SIZE = {};
+const NODEJS_HEAP_SIZE = {};
 
-METRICS.forEach(function(metricType) {
-	NODEJS_HEAP_SIZE[metricType] = 'nodejs_heap_space_size_' + metricType + '_bytes';
+METRICS.forEach(metricType => {
+	NODEJS_HEAP_SIZE[metricType] = `nodejs_heap_space_size_${metricType}_bytes`;
 });
 
-
-module.exports = function() {
-	if(typeof v8 === 'undefined' || typeof v8.getHeapSpaceStatistics !== 'function') {
-		return function() {
-		};
+module.exports = registry => {
+	if (
+		typeof v8 === 'undefined' ||
+		typeof v8.getHeapSpaceStatistics !== 'function'
+	) {
+		return () => {};
 	}
 
-	var gauges = {};
+	const registers = registry ? [registry] : undefined;
 
-	METRICS.forEach(function(metricType) {
-		gauges[metricType] = new Gauge(
-      NODEJS_HEAP_SIZE[metricType],
-      'Process heap space size ' + metricType + ' from node.js in bytes.',
-      ['space']
-    );
+	const gauges = {};
+
+	METRICS.forEach(metricType => {
+		gauges[metricType] = new Gauge({
+			name: NODEJS_HEAP_SIZE[metricType],
+			help: `Process heap space size ${metricType} from node.js in bytes.`,
+			labelNames: ['space'],
+			registers
+		});
 	});
 
-	return function() {
-		var data = {
+	return () => {
+		const data = {
 			total: {},
@@ -49,6 +49,9 @@ used: {},
 		};
-		var now = Date.now();
+		const now = Date.now();
 
-		v8.getHeapSpaceStatistics().forEach(function onEachSpace(space) {
-			var spaceName = space.space_name.substr(0, space.space_name.indexOf('_space'));
+		v8.getHeapSpaceStatistics().forEach(space => {
+			const spaceName = space.space_name.substr(
+				0,
+				space.space_name.indexOf('_space')
+			);
 
@@ -59,5 +62,9 @@ data.total[spaceName] = space.space_size;
 
-			gauges.total.set({space: spaceName}, space.space_size, now);
-			gauges.used.set({space: spaceName}, space.space_used_size, now);
-			gauges.available.set({space: spaceName}, space.space_available_size, now);
+			gauges.total.set({ space: spaceName }, space.space_size, now);
+			gauges.used.set({ space: spaceName }, space.space_used_size, now);
+			gauges.available.set(
+				{ space: spaceName },
+				space.space_available_size,
+				now
+			);
 		});
@@ -69,4 +76,4 @@
 
-module.exports.metricNames = METRICS.map(function(metricType) {
-	return NODEJS_HEAP_SIZE[metricType];
-});
+module.exports.metricNames = METRICS.map(
+	metricType => NODEJS_HEAP_SIZE[metricType]
+);

lib/metrics/helpers/safeMemoryUsage.js

 'use strict';
 
 function safeMemoryUsage() {
-	var memoryUsage;
+	let memoryUsage;
 	try {
 		memoryUsage = process.memoryUsage();
 	} catch (ex) {
-
+		// empty
 	}
@@ -10,0 +10,0 @@

lib/metrics/osMemoryHeap.js

 'use strict';
 
-var Gauge = require('../gauge');
-var linuxVariant = require('./osMemoryHeapLinux');
-var safeMemoryUsage = require('./helpers/safeMemoryUsage');
+const Gauge = require('../gauge');
+const linuxVariant = require('./osMemoryHeapLinux');
+const safeMemoryUsage = require('./helpers/safeMemoryUsage');
 
-var PROCESS_RESIDENT_MEMORY = 'process_resident_memory_bytes';
+const PROCESS_RESIDENT_MEMORY = 'process_resident_memory_bytes';
 
-var notLinuxVariant = function() {
-	var residentMemGauge = new Gauge(PROCESS_RESIDENT_MEMORY, 'Resident memory size in bytes.');
+function notLinuxVariant(registry) {
+	const residentMemGauge = new Gauge({
+		name: PROCESS_RESIDENT_MEMORY,
+		help: 'Resident memory size in bytes.',
+		registers: registry ? [registry] : undefined
+	});
 
-	return function() {
-		var memUsage = safeMemoryUsage();
+	return () => {
+		const memUsage = safeMemoryUsage();
 
 		// I don't think the other things returned from `process.memoryUsage()` is relevant to a standard export
-		if(memUsage) {
+		if (memUsage) {
 			residentMemGauge.set(memUsage.rss, Date.now());
 		}
 	};
-};
+}
 
-module.exports = function() {
-	return process.platform === 'linux' ? linuxVariant() : notLinuxVariant();
-};
+module.exports = registry =>
+	process.platform === 'linux'
+		? linuxVariant(registry)
+		: notLinuxVariant(registry);
 
-module.exports.metricNames = process.platform === 'linux' ? linuxVariant.metricNames : [PROCESS_RESIDENT_MEMORY];
+module.exports.metricNames =
+	process.platform === 'linux'
+		? linuxVariant.metricNames
+		: [PROCESS_RESIDENT_MEMORY];

lib/metrics/osMemoryHeapLinux.js

 'use strict';
 
-var Gauge = require('../gauge');
-var fs = require('fs');
+const Gauge = require('../gauge');
+const fs = require('fs');
 
-var values = ['VmSize', 'VmRSS', 'VmData'];
+const values = ['VmSize', 'VmRSS', 'VmData'];
 
-var PROCESS_RESIDENT_MEMORY = 'process_resident_memory_bytes';
-var PROCESS_VIRTUAL_MEMORY = 'process_virtual_memory_bytes';
-var PROCESS_HEAP = 'process_heap_bytes';
+const PROCESS_RESIDENT_MEMORY = 'process_resident_memory_bytes';
+const PROCESS_VIRTUAL_MEMORY = 'process_virtual_memory_bytes';
+const PROCESS_HEAP = 'process_heap_bytes';
 
 function structureOutput(input) {
-	var returnValue = {};
+	const returnValue = {};
 
-	input.split('\n')
-		.filter(function(s) {
-			return values.some(function(value) {
-				return s.indexOf(value) === 0;
-			});
-		})
-		.forEach(function(string) {
-			var split = string.split(':');
+	input
+		.split('\n')
+		.filter(s => values.some(value => s.indexOf(value) === 0))
+		.forEach(string => {
+			const split = string.split(':');
 
 			// Get the value
-			var value = split[1].trim();
+			let value = split[1].trim();
 			// Remove trailing ` kb`
@@ -37,14 +34,27 @@ value = value.substr(0, value.length - 3);
 
-module.exports = function() {
-	var residentMemGauge = new Gauge(PROCESS_RESIDENT_MEMORY, 'Resident memory size in bytes.');
-	var virtualMemGauge = new Gauge(PROCESS_VIRTUAL_MEMORY, 'Virtual memory size in bytes.');
-	var heapSizeMemGauge = new Gauge(PROCESS_HEAP , 'Process heap size in bytes.');
+module.exports = registry => {
+	const registers = registry ? [registry] : undefined;
+	const residentMemGauge = new Gauge({
+		name: PROCESS_RESIDENT_MEMORY,
+		help: 'Resident memory size in bytes.',
+		registers
+	});
+	const virtualMemGauge = new Gauge({
+		name: PROCESS_VIRTUAL_MEMORY,
+		help: 'Virtual memory size in bytes.',
+		registers
+	});
+	const heapSizeMemGauge = new Gauge({
+		name: PROCESS_HEAP,
+		help: 'Process heap size in bytes.',
+		registers
+	});
 
-	return function() {
-		fs.readFile('/proc/self/status', 'utf8', function(err, status) {
-			if(err) {
+	return () => {
+		fs.readFile('/proc/self/status', 'utf8', (err, status) => {
+			if (err) {
 				return;
 			}
-			var now = Date.now();
-			var structuredOutput = structureOutput(status);
+			const now = Date.now();
+			const structuredOutput = structureOutput(status);
 
@@ -58,2 +68,6 @@ residentMemGauge.set(structuredOutput.VmRSS, now);
 
-module.exports.metricNames = [PROCESS_RESIDENT_MEMORY, PROCESS_VIRTUAL_MEMORY, PROCESS_HEAP];
+module.exports.metricNames = [
+	PROCESS_RESIDENT_MEMORY,
+	PROCESS_VIRTUAL_MEMORY,
+	PROCESS_HEAP
+];

lib/metrics/processCpuTotal.js

 'use strict';
 
-var Counter = require('../counter');
-var PROCESS_CPU_USER_SECONDS = 'process_cpu_user_seconds_total';
-var PROCESS_CPU_SYSTEM_SECONDS = 'process_cpu_system_seconds_total';
-var PROCESS_CPU_SECONDS = 'process_cpu_seconds_total';
+const Counter = require('../counter');
+const PROCESS_CPU_USER_SECONDS = 'process_cpu_user_seconds_total';
+const PROCESS_CPU_SYSTEM_SECONDS = 'process_cpu_system_seconds_total';
+const PROCESS_CPU_SECONDS = 'process_cpu_seconds_total';
 
-module.exports = function() {
+module.exports = registry => {
 	// Don't do anything if the function doesn't exist (introduced in node@6.1.0)
-	if(typeof process.cpuUsage !== 'function') {
-		return function() {
-		};
+	if (typeof process.cpuUsage !== 'function') {
+		return () => {};
 	}
 
-	var cpuUserUsageCounter = new Counter(PROCESS_CPU_USER_SECONDS,
-		'Total user CPU time spent in seconds.');
-	var cpuSystemUsageCounter = new Counter(PROCESS_CPU_SYSTEM_SECONDS,
-		'Total system CPU time spent in seconds.');
-	var cpuUsageCounter = new Counter(PROCESS_CPU_SECONDS,
-		'Total user and system CPU time spent in seconds.');
+	const registers = registry ? [registry] : undefined;
 
-	var lastCpuUsage = process.cpuUsage();
+	const cpuUserUsageCounter = new Counter({
+		name: PROCESS_CPU_USER_SECONDS,
+		help: 'Total user CPU time spent in seconds.',
+		registers
+	});
+	const cpuSystemUsageCounter = new Counter({
+		name: PROCESS_CPU_SYSTEM_SECONDS,
+		help: 'Total system CPU time spent in seconds.',
+		registers
+	});
+	const cpuUsageCounter = new Counter({
+		name: PROCESS_CPU_SECONDS,
+		help: 'Total user and system CPU time spent in seconds.',
+		registers
+	});
 
-	return function() {
-		var cpuUsage = process.cpuUsage();
-		var now = Date.now();
+	let lastCpuUsage = process.cpuUsage();
 
-		var userUsageMicros = cpuUsage.user - lastCpuUsage.user;
-		var systemUsageMicros = cpuUsage.system - lastCpuUsage.system;
+	return () => {
+		const cpuUsage = process.cpuUsage();
+		const now = Date.now();
 
+		const userUsageMicros = cpuUsage.user - lastCpuUsage.user;
+		const systemUsageMicros = cpuUsage.system - lastCpuUsage.system;
+
 		lastCpuUsage = cpuUsage;
@@ -40,3 +50,5 @@
 module.exports.metricNames = [
-	PROCESS_CPU_USER_SECONDS, PROCESS_CPU_SYSTEM_SECONDS, PROCESS_CPU_SECONDS
+	PROCESS_CPU_USER_SECONDS,
+	PROCESS_CPU_SYSTEM_SECONDS,
+	PROCESS_CPU_SECONDS
 ];

lib/metrics/processHandles.js

 'use strict';
 
-var Gauge = require('../gauge');
+const Gauge = require('../gauge');
 
-var NODEJS_ACTIVE_HANDLES = 'nodejs_active_handles_total';
+const NODEJS_ACTIVE_HANDLES = 'nodejs_active_handles_total';
 
-module.exports = function() {
+module.exports = registry => {
 	// Don't do anything if the function is removed in later nodes (exists in node@6)
-	if(typeof process._getActiveHandles !== 'function') {
-		return function() {
-		};
+	if (typeof process._getActiveHandles !== 'function') {
+		return () => {};
 	}
 
-	var gauge = new Gauge(NODEJS_ACTIVE_HANDLES, 'Number of active handles.');
+	const gauge = new Gauge({
+		name: NODEJS_ACTIVE_HANDLES,
+		help: 'Number of active handles.',
+		registers: registry ? [registry] : undefined
+	});
 
-	return function() {
+	return () => {
 		gauge.set(process._getActiveHandles().length, Date.now());
@@ -18,0 +21,0 @@ };

lib/metrics/processMaxFileDescriptors.js

 'use strict';
 
-var Gauge = require('../gauge');
-var fs = require('fs');
+const Gauge = require('../gauge');
+const fs = require('fs');
 
-var PROCESS_MAX_FDS = 'process_max_fds';
+const PROCESS_MAX_FDS = 'process_max_fds';
 
-module.exports = function() {
-	var isSet = false;
+module.exports = registry => {
+	let isSet = false;
 
-	if(process.platform !== 'linux') {
-		return function() {
-		};
+	if (process.platform !== 'linux') {
+		return () => {};
 	}
+	const fileDescriptorsGauge = new Gauge({
+		name: PROCESS_MAX_FDS,
+		help: 'Maximum number of open file descriptors.',
+		registers: registry ? [registry] : undefined
+	});
 
-	var fileDescriptorsGauge = new Gauge(PROCESS_MAX_FDS, 'Maximum number of open file descriptors.');
-
-	return function() {
-		if(isSet) {
+	return () => {
+		if (isSet) {
 			return;
 		}
 
-		fs.readFile('/proc/sys/fs/file-max', 'utf8', function(err, maxFds) {
-			if(err) {
+		fs.readFile('/proc/sys/fs/file-max', 'utf8', (err, maxFds) => {
+			if (err) {
 				return;
@@ -26,0 +28,0 @@ }

lib/metrics/processOpenFileDescriptors.js

 'use strict';
 
-var Gauge = require('../gauge');
-var fs = require('fs');
+const Gauge = require('../gauge');
+const fs = require('fs');
 
-var PROCESS_OPEN_FDS = 'process_open_fds';
+const PROCESS_OPEN_FDS = 'process_open_fds';
 
-module.exports = function() {
-	if(process.platform !== 'linux') {
-		return function() {
-		};
+module.exports = registry => {
+	if (process.platform !== 'linux') {
+		return () => {};
 	}
 
-	var fileDescriptorsGauge = new Gauge(PROCESS_OPEN_FDS, 'Number of open file descriptors.');
+	const fileDescriptorsGauge = new Gauge({
+		name: PROCESS_OPEN_FDS,
+		help: 'Number of open file descriptors.',
+		registers: registry ? [registry] : undefined
+	});
 
-	return function() {
-		fs.readdir('/proc/self/fd', function(err, list) {
-			if(err) {
+	return () => {
+		fs.readdir('/proc/self/fd', (err, list) => {
+			if (err) {
 				return;
@@ -20,0 +23,0 @@ }

lib/metrics/processRequests.js

 'use strict';
 
-var Gauge = require('../gauge');
+const Gauge = require('../gauge');
 
-var NODEJS_ACTIVE_REQUESTS = 'nodejs_active_requests_total';
+const NODEJS_ACTIVE_REQUESTS = 'nodejs_active_requests_total';
 
-module.exports = function() {
+module.exports = registry => {
 	// Don't do anything if the function is removed in later nodes (exists in node@6)
-	if(typeof process._getActiveRequests !== 'function') {
-		return function() {
-		};
+	if (typeof process._getActiveRequests !== 'function') {
+		return () => {};
 	}
 
-	var gauge = new Gauge(NODEJS_ACTIVE_REQUESTS, 'Number of active requests.');
+	const gauge = new Gauge({
+		name: NODEJS_ACTIVE_REQUESTS,
+		help: 'Number of active requests.',
+		registers: registry ? [registry] : undefined
+	});
 
-	return function() {
+	return () => {
 		gauge.set(process._getActiveRequests().length, Date.now());
@@ -18,0 +21,0 @@ };

lib/metrics/processStartTime.js

 'use strict';
 
-var Gauge = require('../gauge');
-var nowInSeconds = Math.round(Date.now() / 1000 - process.uptime());
+const Gauge = require('../gauge');
+const nowInSeconds = Math.round(Date.now() / 1000 - process.uptime());
 
-var PROCESS_START_TIME = 'process_start_time_seconds';
+const PROCESS_START_TIME = 'process_start_time_seconds';
 
-module.exports = function() {
-	var cpuUserGauge = new Gauge(PROCESS_START_TIME, 'Start time of the process since unix epoch in seconds.');
-	var isSet = false;
+module.exports = registry => {
+	const cpuUserGauge = new Gauge({
+		name: PROCESS_START_TIME,
+		help: 'Start time of the process since unix epoch in seconds.',
+		registers: registry ? [registry] : undefined
+	});
+	let isSet = false;
 
-	return function() {
-		if(isSet) {
+	return () => {
+		if (isSet) {
 			return;
@@ -15,0 +19,0 @@ }

lib/metrics/version.js

 'use strict';
 
-var Gauge = require('../gauge');
-var version = process.version;
-var versionSegments = version.slice(1).split('.').map(Number);
+const Gauge = require('../gauge');
+const version = process.version;
+const versionSegments = version.slice(1).split('.').map(Number);
 
-var NODE_VERSION_INFO = 'nodejs_version_info';
+const NODE_VERSION_INFO = 'nodejs_version_info';
 
-module.exports = function() {
-	var nodeVersionGauge = new Gauge(NODE_VERSION_INFO, 'Node.js version info.', ['version', 'major', 'minor', 'patch']);
-	var isSet = false;
+module.exports = registry => {
+	const nodeVersionGauge = new Gauge({
+		name: NODE_VERSION_INFO,
+		help: 'Node.js version info.',
+		labelNames: ['version', 'major', 'minor', 'patch'],
+		registers: registry ? [registry] : undefined
+	});
+	let isSet = false;
 
-	return function() {
-		if(isSet) {
+	return () => {
+		if (isSet) {
 			return;
 		}
-		nodeVersionGauge.labels(version, versionSegments[0], versionSegments[1], versionSegments[2]).set(1);
+		nodeVersionGauge
+			.labels(
+				version,
+				versionSegments[0],
+				versionSegments[1],
+				versionSegments[2]
+			)
+			.set(1);
 		isSet = true;
@@ -19,0 +31,0 @@ };

lib/pushgateway.js

 'use strict';
 
-var url = require('url');
-var http = require('http');
-var https = require('https');
-var register = require('./register');
+const url = require('url');
+const http = require('http');
+const https = require('https');
+const globalRegistry = require('./registry').globalRegistry;
 
-function Pushgateway(gatewayUrl, options, registry) {
-	if(!registry) {
-		registry = register;
+class Pushgateway {
+	constructor(gatewayUrl, options, registry) {
+		if (!registry) {
+			registry = globalRegistry;
+		}
+		this.registry = registry;
+		this.gatewayUrl = gatewayUrl;
+		this.requestOptions = Object.assign({}, options);
 	}
-	this.registry = registry;
-	this.gatewayUrl = gatewayUrl;
-	this.requestOptions = Object.assign({}, options);
-}
 
-Pushgateway.prototype.pushAdd = function(params, callback) {
-	if(!params || !params.jobName) {
-		throw new Error('Missing jobName parameter');
-	}
+	pushAdd(params, callback) {
+		if (!params || !params.jobName) {
+			throw new Error('Missing jobName parameter');
+		}
 
-	useGateway.call(this, 'POST', params.jobName, params.groupings, callback);
-};
-Pushgateway.prototype.push = function(params, callback) {
-	if(!params || !params.jobName) {
-		throw new Error('Missing jobName parameter');
+		useGateway.call(this, 'POST', params.jobName, params.groupings, callback);
 	}
 
-	useGateway.call(this, 'PUT', params.jobName, params.groupings, callback);
-};
-Pushgateway.prototype.delete = function(params, callback) {
-	if(!params || !params.jobName) {
-		throw new Error('Missing jobName parameter');
+	push(params, callback) {
+		if (!params || !params.jobName) {
+			throw new Error('Missing jobName parameter');
+		}
+
+		useGateway.call(this, 'PUT', params.jobName, params.groupings, callback);
 	}
 
-	useGateway.call(this, 'DELETE', params.jobName, params.groupings, callback);
-};
+	delete(params, callback) {
+		if (!params || !params.jobName) {
+			throw new Error('Missing jobName parameter');
+		}
 
-
+		useGateway.call(this, 'DELETE', params.jobName, params.groupings, callback);
+	}
+}
 function useGateway(method, job, groupings, callback) {
-	var gatewayUrlParsed = url.parse(this.gatewayUrl);
-	var gatewayUrlPath = gatewayUrlParsed.pathname && gatewayUrlParsed.pathname !== '/' ? gatewayUrlParsed.pathname : '';
-	var path = [gatewayUrlPath, '/metrics/job/', encodeURIComponent(job), generateGroupings(groupings)].join('');
+	const gatewayUrlParsed = url.parse(this.gatewayUrl);
+	const gatewayUrlPath =
+		gatewayUrlParsed.pathname && gatewayUrlParsed.pathname !== '/'
+			? gatewayUrlParsed.pathname
+			: '';
+	const path = `${gatewayUrlPath}/metrics/job/${encodeURIComponent(
+		job
+	)}${generateGroupings(groupings)}`;
 
-	var target = url.resolve(this.gatewayUrl, path);
-	var requestParams = url.parse(target);
-	var httpModule = isHttps(requestParams.href) ? https : http;
-	var options = Object.assign(requestParams, this.requestOptions, {
-		method: method
+	const target = url.resolve(this.gatewayUrl, path);
+	const requestParams = url.parse(target);
+	const httpModule = isHttps(requestParams.href) ? https : http;
+	const options = Object.assign(requestParams, this.requestOptions, {
+		method
 	});
 
-	var req = httpModule.request(options, function(res) {
-		var body = '';
+	const req = httpModule.request(options, res => {
+		let body = '';
 		res.setEncoding('utf8');
-		res.on('data', function(chunk) {
+		res.on('data', chunk => {
 			body += chunk;
 		});
-		res.on('end', function() {
+		res.on('end', () => {
 			callback(null, res, body);
 		});
 	});
-	req.on('error', function(err) {
+	req.on('error', err => {
 		callback(err);
 	});
 
-	if(method !== 'DELETE') {
+	if (method !== 'DELETE') {
 		req.write(this.registry.metrics());
@@ -73,8 +80,10 @@ }
 function generateGroupings(groupings) {
-	if(!groupings) {
+	if (!groupings) {
 		return '';
 	}
-	return Object.keys(groupings).map(function(key) {
-		return ['/', encodeURIComponent(key), '/', encodeURIComponent(groupings[key])].join('');
-	}).join('');
+	return Object.keys(groupings)
+		.map(
+			key => `/${encodeURIComponent(key)}/${encodeURIComponent(groupings[key])}`
+		)
+		.join('');
 }
@@ -81,0 +90,0 @@

lib/registry.js

@@ -7,3 +7,3 @@ 'use strict';
 function escapeLabelValue(str) {
-	if(typeof str !== 'string') {
+	if (typeof str !== 'string') {
 		return str;
@@ -13,29 +13,30 @@ }
 }
-var registry = (function() {
-	var _metrics = {};
-	var self;
-	function Registry() {
-		self = this;
+
+class Registry {
+	constructor() {
+		this._metrics = {};
+		this._defaultLabels = {};
 	}
 
-	Registry.prototype.getMetricsAsArray = function() {
-		return Object.keys(_metrics)
-			.map(self.getSingleMetric, self);
-	};
+	getMetricsAsArray() {
+		return Object.keys(this._metrics).map(this.getSingleMetric, this);
+	}
 
-	Registry.prototype.getMetricAsPrometheusString = function(metric) {
-		var item = metric.get();
-		var name = escapeString(item.name);
-		var help = escapeString(item.help);
+	getMetricAsPrometheusString(metric) {
+		const item = metric.get();
+		const name = escapeString(item.name);
+		let help = escapeString(item.help);
 		help = ['#', 'HELP', name, help].join(' ');
-		var type = ['#', 'TYPE', name, item.type].join(' ');
+		const type = ['#', 'TYPE', name, item.type].join(' ');
 
-		var values = (item.values || []).reduce(function(valAcc, val) {
-			var labels = Object.keys(val.labels || {}).map(function(key) {
-				return key + '="' + escapeLabelValue(val.labels[key]) + '"';
-			});
+		const values = (item.values || []).reduce((valAcc, val) => {
+			const merged = Object.assign({}, this._defaultLabels, val.labels);
 
-			var metricName = val.metricName || item.name;
-			if(labels.length) {
-				metricName += '{' + labels.join(',') + '}';
+			const labels = Object.keys(merged).map(
+				key => `${key}="${escapeLabelValue(merged[key])}"`
+			);
+
+			let metricName = val.metricName || item.name;
+			if (labels.length) {
+				metricName += `{${labels.join(',')}}`;
 			}
@@ -48,57 +49,68 @@
 
-		var acc = [help, type, values].join('\n');
+		const acc = [help, type, values].join('\n');
 		return acc;
-	};
+	}
 
-	Registry.prototype.metrics = function() {
-		return self.getMetricsAsArray()
+	metrics() {
+		return this.getMetricsAsArray()
 			.map(this.getMetricAsPrometheusString, this)
 			.join('\n');
-	};
+	}
 
-	Registry.prototype.registerMetric = function(metricFn) {
-		if(_metrics[metricFn.name] && _metrics[metricFn.name] !== metricFn) {
-			throw new Error('A metric with the name ' + metricFn.name + ' has already been registered.');
+	registerMetric(metricFn) {
+		if (
+			this._metrics[metricFn.name] &&
+			this._metrics[metricFn.name] !== metricFn
+		) {
+			throw new Error(
+				`A metric with the name ${metricFn.name} has already been registered.`
+			);
 		}
 
-		_metrics[metricFn.name] = metricFn;
-	};
+		this._metrics[metricFn.name] = metricFn;
+	}
 
-	Registry.prototype.clear = function() {
-		_metrics = {};
-	};
+	clear() {
+		this._metrics = {};
+		this._defaultLabels = {};
+	}
 
-	Registry.prototype.getMetricsAsJSON = function() {
-		return self.getMetricsAsArray().map(function(metric) {
-			return metric.get();
-		});
-	};
+	getMetricsAsJSON() {
+		return this.getMetricsAsArray().map(metric => metric.get());
+	}
 
-	Registry.prototype.removeSingleMetric = function(name) {
-		delete _metrics[name];
-	};
+	removeSingleMetric(name) {
+		delete this._metrics[name];
+	}
 
-	Registry.prototype.getSingleMetricAsString = function(name) {
-		return this.getMetricAsPrometheusString(_metrics[name]);
-	};
+	getSingleMetricAsString(name) {
+		return this.getMetricAsPrometheusString(this._metrics[name]);
+	}
 
-	Registry.prototype.getSingleMetric = function(name) {
-		return _metrics[name];
-	};
+	getSingleMetric(name) {
+		return this._metrics[name];
+	}
 
-	Registry.prototype.contentType = 'text/plain; version=0.0.4; charset=utf-8';
-	return new Registry();
-});
+	setDefaultLabels(labels) {
+		this._defaultLabels = labels;
+	}
 
-module.exports = registry;
+	get contentType() {
+		return 'text/plain; version=0.0.4; charset=utf-8';
+	}
 
-registry.merge = function(registers) {
-	var mergedRegistry = new registry();
+	static merge(registers) {
+		const mergedRegistry = new Registry();
 
-	var metricsToMerge = registers.reduce(function(acc, reg) {
-		return acc.concat(reg.getMetricsAsArray());
-	}, []);
+		const metricsToMerge = registers.reduce(
+			(acc, reg) => acc.concat(reg.getMetricsAsArray()),
+			[]
+		);
 
-	metricsToMerge.forEach(mergedRegistry.registerMetric);
-	return mergedRegistry;
-};
+		metricsToMerge.forEach(mergedRegistry.registerMetric, mergedRegistry);
+		return mergedRegistry;
+	}
+}
+
+module.exports = Registry;
+module.exports.globalRegistry = new Registry();

lib/summary.js

@@ -6,105 +6,134 @@ /**
 
-var globalRegistry = require('./register');
-var type = 'summary';
-var isNumber = require('./util').isNumber;
-var extend = require('util-extend');
-var getProperties = require('./util').getPropertiesFromObj;
-var getLabels = require('./util').getLabels;
-var hashObject = require('./util').hashObject;
-var validateLabels = require('./validation').validateLabel;
-var validateMetricName = require('./validation').validateMetricName;
-var validateLabelNames = require('./validation').validateLabelName;
-var TDigest = require('tdigest').TDigest;
-var isObject = require('util').isObject;
-var extend = require('util-extend');
+const globalRegistry = require('./registry').globalRegistry;
+const type = 'summary';
+const isNumber = require('./util').isNumber;
+const getProperties = require('./util').getPropertiesFromObj;
+const getLabels = require('./util').getLabels;
+const hashObject = require('./util').hashObject;
+const validateLabels = require('./validation').validateLabel;
+const validateMetricName = require('./validation').validateMetricName;
+const validateLabelNames = require('./validation').validateLabelName;
+const TDigest = require('tdigest').TDigest;
+const isObject = require('util').isObject;
+const printDeprecationObjectConstructor = require('./util')
+	.printDeprecationObjectConstructor;
 
-/**
- * Summary
- * @param {string} name - Name of the metric
- * @param {string} help - Help for the metric
- * @param {object|Array.<string>} labelsOrConf - Either array of label names or config object as a key-value object
- * @param {object} conf - Configuration object
- * @constructor
- */
-function Summary(name, help, labelsOrConf, conf) {
-	var config;
-	if(isObject(name)) {
-		config = extend({
-			percentiles: [0.01, 0.05, 0.5, 0.9, 0.95, 0.99, 0.999],
-			labelNames: [],
-			registers: [ globalRegistry ],
-		}, name);
-	} else {
-		var obj;
-		var labels = [];
+class Summary {
+	/**
+	 * Summary
+	 * @param {string} name - Name of the metric
+	 * @param {string} help - Help for the metric
+	 * @param {object|Array.<string>} labelsOrConf - Either array of label names or config object as a key-value object
+	 * @param {object} conf - Configuration object
+	 */
+	constructor(name, help, labelsOrConf, conf) {
+		let config;
+		if (isObject(name)) {
+			config = Object.assign(
+				{
+					percentiles: [0.01, 0.05, 0.5, 0.9, 0.95, 0.99, 0.999],
+					labelNames: []
+				},
+				name
+			);
 
-		if(Array.isArray(labelsOrConf)) {
-			obj = conf || {};
-			labels = labelsOrConf;
+			if (!config.registers) {
+				config.registers = [globalRegistry];
+			}
 		} else {
-			obj = labelsOrConf || {};
+			let obj;
+			let labels = [];
+
+			if (Array.isArray(labelsOrConf)) {
+				obj = conf || {};
+				labels = labelsOrConf;
+			} else {
+				obj = labelsOrConf || {};
+			}
+
+			printDeprecationObjectConstructor();
+
+			config = {
+				name,
+				help,
+				labelNames: labels,
+				percentiles: configurePercentiles(obj.percentiles),
+				registers: [globalRegistry]
+			};
 		}
 
-		config = {
-			name: name,
-			help: help,
-			labelNames: labels,
-			percentiles: configurePercentiles(obj.percentiles),
-			registers: [ globalRegistry ]
-		};
-	}
+		validateInput(config.name, config.help, config.labelNames);
 
-	validateInput(config.name, config.help, config.labelNames);
+		this.name = config.name;
+		this.help = config.help;
 
-	this.name = config.name;
-	this.help = config.help;
+		this.percentiles = config.percentiles;
+		this.hashMap = {};
+		this.labelNames = config.labelNames || [];
 
-	this.percentiles = config.percentiles;
-	this.hashMap = {};
-	this.labelNames = config.labelNames || [];
+		config.registers.forEach(registryInstance =>
+			registryInstance.registerMetric(this)
+		);
+	}
 
-	var metric = this;
-	config.registers.forEach(function(registryInstance) {
-		registryInstance.registerMetric(metric);
-	});
-}
+	/**
+	 * Observe a value
+	 * @param {object} labels - Object with labels where key is the label key and value is label value. Can only be one level deep
+	 * @param {Number} value - Value to observe
+	 * @returns {void}
+	 */
+	observe(labels, value) {
+		observe.call(this, labels === 0 ? 0 : labels || {})(value);
+	}
 
-/**
- * Observe a value
- * @param {object} labels - Object with labels where key is the label key and value is label value. Can only be one level deep
- * @param {Number} value - Value to observe
- * @returns {void}
- */
-Summary.prototype.observe = function(labels, value) {
-	observe.call(this, labels === 0 ? 0 : (labels || {}))(value);
-};
+	get() {
+		const data = getProperties(this.hashMap);
+		const values = [];
+		data.forEach(s => {
+			extractSummariesForExport(s, this.percentiles).forEach(v => {
+				values.push(v);
+			});
+			values.push(getSumForExport(s, this));
+			values.push(getCountForExport(s, this));
+		});
 
-Summary.prototype.get = function() {
-	var summary = this;
-	var data = getProperties(summary.hashMap);
-	var values = [];
-	data.forEach(function(s) {
-		extractSummariesForExport(s, summary.percentiles).forEach(function(v) {
-			values.push(v);
+		return {
+			name: this.name,
+			help: this.help,
+			type,
+			values
+		};
+	}
+
+	reset() {
+		const data = getProperties(this.hashMap);
+		data.forEach(s => {
+			s.td.reset();
+			s.count = 0;
+			s.sum = 0;
 		});
-		values.push(getSumForExport(s, summary));
-		values.push(getCountForExport(s, summary));
-	});
+	}
 
-	return {
-		name: this.name,
-		help: this.help,
-		type: type,
-		values: values
-	};
-};
+	/**
+	 * Start a timer that could be used to logging durations
+	 * @param {object} labels - Object with labels where key is the label key and value is label value. Can only be one level deep
+	 * @returns {function} - Function to invoke when you want to stop the timer and observe the duration in seconds
+	 * @example
+	 * var end = summary.startTimer();
+	 * makeExpensiveXHRRequest(function(err, res) {
+	 *	end(); //Observe the duration of expensiveXHRRequest
+	 * });
+	 */
+	startTimer(labels) {
+		return startTimer.call(this, labels)();
+	}
 
-Summary.prototype.reset = function() {
-	var data = getProperties(this.hashMap);
-	data.forEach(function(s) {
-		s.td.reset();
-		s.count = 0;
-		s.sum = 0;
-	});
-};
+	labels() {
+		const labels = getLabels(this.labelNames, arguments);
+		return {
+			observe: observe.call(this, labels),
+			startTimer: startTimer.call(this, labels)
+		};
+	}
+}
 
@@ -114,6 +143,6 @@ function extractSummariesForExport(summaryOfLabels, percentiles) {
 
-	return percentiles.map(function(percentile) {
-		var percentileValue = summaryOfLabels.td.percentile(percentile);
+	return percentiles.map(percentile => {
+		const percentileValue = summaryOfLabels.td.percentile(percentile);
 		return {
-			labels: extend({ quantile: percentile }, summaryOfLabels.labels),
+			labels: Object.assign({ quantile: percentile }, summaryOfLabels.labels),
 			value: percentileValue ? percentileValue : 0
@@ -126,3 +155,3 @@ };
 	return {
-		metricName: summary.name + '_count',
+		metricName: `${summary.name}_count`,
 		labels: value.labels,
@@ -135,3 +164,3 @@ value: value.count
 	return {
-		metricName: summary.name + '_sum',
+		metricName: `${summary.name}_sum`,
 		labels: value.labels,
@@ -142,32 +171,11 @@ value: value.sum
 
-
-/**
- * Start a timer that could be used to logging durations
- * @param {object} labels - Object with labels where key is the label key and value is label value. Can only be one level deep
- * @returns {function} - Function to invoke when you want to stop the timer and observe the duration in seconds
- * @example
- * var end = summary.startTimer();
- * makeExpensiveXHRRequest(function(err, res) {
- *	end(); //Observe the duration of expensiveXHRRequest
- * });
- */
-Summary.prototype.startTimer = function(labels) {
-	return startTimer.call(this, labels)();
-};
-
-Summary.prototype.labels = function() {
-	var labels = getLabels(this.labelNames, arguments);
-	return {
-		observe: observe.call(this, labels),
-		startTimer: startTimer.call(this, labels)
-	};
-};
-
 function startTimer(startLabels) {
-	var summary = this;
-	return function() {
-		var start = process.hrtime();
-		return function(endLabels) {
-			var delta = process.hrtime(start);
-			summary.observe(extend(startLabels || {}, endLabels),  delta[0] + delta[1] / 1e9);
+	return () => {
+		const start = process.hrtime();
+		return endLabels => {
+			const delta = process.hrtime(start);
+			this.observe(
+				Object.assign(startLabels || {}, endLabels),
+				delta[0] + delta[1] / 1e9
+			);
 		};
@@ -178,19 +186,19 @@ };
 function validateInput(name, help, labels) {
-	if(!help) {
+	if (!help) {
 		throw new Error('Missing mandatory help parameter');
 	}
-	if(!name) {
+	if (!name) {
 		throw new Error('Missing mandatory name parameter');
 	}
 
-	if(!validateMetricName(name)) {
+	if (!validateMetricName(name)) {
 		throw new Error('Invalid metric name');
 	}
 
-	if(!validateLabelNames(labels)) {
+	if (!validateLabelNames(labels)) {
 		throw new Error('Invalid label name');
 	}
 
-	labels.forEach(function(label) {
-		if(label === 'quantile') {
+	labels.forEach(label => {
+		if (label === 'quantile') {
 			throw new Error('quantile is a reserved label keyword');
@@ -202,4 +210,6 @@ }
 function configurePercentiles(configuredPercentiles) {
-	var defaultPercentiles = [0.01, 0.05, 0.5, 0.9, 0.95, 0.99, 0.999];
-	return [].concat((configuredPercentiles || defaultPercentiles)).sort(sortAscending);
+	const defaultPercentiles = [0.01, 0.05, 0.5, 0.9, 0.95, 0.99, 0.999];
+	return []
+		.concat(configuredPercentiles || defaultPercentiles)
+		.sort(sortAscending);
 }
@@ -211,34 +221,14 @@
 
-function createValuePair(labels, value, metricName) {
-	return {
-		labels: labels,
-		value: value,
-		metricName: metricName
-	};
-}
-
-function findBound(upperBounds, value) {
-	for(var i = 0; i < upperBounds.length; i++) {
-		var bound = upperBounds[i];
-		if(value <= bound) {
-			return bound;
-		}
-
-	}
-	return -1;
-}
-
 function observe(labels) {
-	var summary = this;
-	return function(value) {
-		var labelValuePair = convertLabelsAndValues(labels, value);
+	return value => {
+		const labelValuePair = convertLabelsAndValues(labels, value);
 
-		validateLabels(summary.labelNames, summary.labels);
-		if(!isNumber(labelValuePair.value)) {
+		validateLabels(this.labelNames, this.labels);
+		if (!isNumber(labelValuePair.value)) {
 			throw new Error('Value is not a valid number', labelValuePair.value);
 		}
 
-		var hash = hashObject(labelValuePair.labels);
-		var summaryOfLabel = summary.hashMap[hash];
-		if(!summaryOfLabel) {
+		const hash = hashObject(labelValuePair.labels);
+		let summaryOfLabel = this.hashMap[hash];
+		if (!summaryOfLabel) {
 			summaryOfLabel = {
@@ -255,3 +245,3 @@ labels: labelValuePair.labels,
 		summaryOfLabel.sum += labelValuePair.value;
-		summary.hashMap[hash] = summaryOfLabel;
+		this.hashMap[hash] = summaryOfLabel;
 	};
@@ -261,3 +251,3 @@ }
 function convertLabelsAndValues(labels, value) {
-	if(isNumber(labels)) {
+	if (isNumber(labels)) {
 		return {
@@ -269,4 +259,4 @@ value: labels,
 	return {
-		labels: labels,
-		value: value
+		labels,
+		value
 	};
@@ -273,0 +263,0 @@ }

lib/util.js

 'use strict';
 
+const deprecationsEmitted = {};
+
 exports.isNumber = isNumber;
@@ -7,15 +9,14 @@ exports.isDate = isDate;
 exports.getPropertiesFromObj = function(hashMap) {
-	var obj = Object.keys(hashMap).map(function(x) {
-		return hashMap[x];
-	});
+	const obj = Object.keys(hashMap).map(x => hashMap[x]);
 	return obj;
 };
 
-
 exports.setValue = function setValue(hashMap, value, labels, timestamp) {
-	var hash = hashObject(labels);
+	const hash = hashObject(labels);
 	hashMap[hash] = {
 		value: isNumber(value) ? value : 0,
 		labels: labels || {},
-		timestamp: isDate(timestamp) ? timestamp.valueOf() : isNumber(timestamp) ? timestamp : undefined
+		timestamp: isDate(timestamp)
+			? timestamp.valueOf()
+			: isNumber(timestamp) ? timestamp : undefined
 	};
@@ -25,9 +26,10 @@ return hashMap;
 
+// TODO: For node 6, use rest params
 exports.getLabels = function(labelNames, args) {
-	if(labelNames.length !== args.length) {
+	if (labelNames.length !== args.length) {
 		throw new Error('Invalid number of arguments');
 	}
 
-	var argsAsArray = Array.prototype.slice.call(args);
-	return labelNames.reduce(function(acc, label, index) {
+	const argsAsArray = Array.prototype.slice.call(args);
+	return labelNames.reduce((acc, label, index) => {
 		acc[label] = argsAsArray[index];
@@ -38,3 +40,2 @@ return acc;
 
-
 function hashObject(labels) {
@@ -44,14 +45,14 @@ // We don't actually need a hash here. We just need a string that
 	// calls with equivalent labels objects.
-	var keys = Object.keys(labels);
-	if(keys.length === 0) {
+	let keys = Object.keys(labels);
+	if (keys.length === 0) {
 		return '';
 	}
 	// else
-	if(keys.length > 1) {
-		keys = keys.sort();		// need consistency across calls
+	if (keys.length > 1) {
+		keys = keys.sort(); // need consistency across calls
 	}
 
-	var elems = [];
-	for(var i = 0; i < keys.length; i++) {
-		elems.push(keys[i] + ':' + labels[keys[i]]);
+	const elems = [];
+	for (let i = 0; i < keys.length; i++) {
+		elems.push(`${keys[i]}:${labels[keys[i]]}`);
 	}
@@ -72,1 +73,29 @@ return elems.join(',');
 };
+
+function printDeprecation(msg) {
+	if (deprecationsEmitted[msg]) {
+		return;
+	}
+
+	deprecationsEmitted[msg] = true;
+
+	if (process.emitWarning) {
+		process.emitWarning(msg, 'DeprecationWarning');
+	} else {
+		// Check can be removed when we only support node@>=6
+		// eslint-disable-next-line no-console
+		console.warn(new Error(msg));
+	}
+}
+
+exports.printDeprecationObjectConstructor = () => {
+	printDeprecation(
+		'prom-client - Passing a non-object to metrics constructor is deprecated'
+	);
+};
+
+exports.printDeprecationCollectDefaultMetricsNumber = timeout => {
+	printDeprecation(
+		`prom-client - A number to defaultMetrics is deprecated, please use \`collectDefaultMetrics({ timeout: ${timeout} })\`.`
+	);
+};

lib/validation.js

 'use strict';
 
-var util = require('util');
+const util = require('util');
 
 // These are from https://prometheus.io/docs/concepts/data_model/#metric-names-and-labels
-var metricRegexp = /^[a-zA-Z_:][a-zA-Z0-9_:]*$/;
-var labelRegexp = /^[a-zA-Z_][a-zA-Z0-9_]*$/;
+const metricRegexp = /^[a-zA-Z_:][a-zA-Z0-9_:]*$/;
+const labelRegexp = /^[a-zA-Z_][a-zA-Z0-9_]*$/;
 
@@ -14,5 +14,5 @@ exports.validateMetricName = function(name) {
 exports.validateLabelName = function(names) {
-	var valid = true;
-	(names || []).forEach(function(name) {
-		if(!labelRegexp.test(name)) {
+	let valid = true;
+	(names || []).forEach(name => {
+		if (!labelRegexp.test(name)) {
 			valid = false;
@@ -25,7 +25,11 @@ }
 exports.validateLabel = function validateLabel(savedLabels, labels) {
-	Object.keys(labels).forEach(function(label) {
-		if(savedLabels.indexOf(label) === -1) {
-			throw new Error('Added label "' + label + '" is not included in initial labelset: ' + util.inspect(savedLabels));
+	Object.keys(labels).forEach(label => {
+		if (savedLabels.indexOf(label) === -1) {
+			throw new Error(
+				`Added label "${label}" is not included in initial labelset: ${util.inspect(
+					savedLabels
+				)}`
+			);
 		}
 	});
 };

package.json

 {
   "name": "prom-client",
-  "version": "9.1.1",
+  "version": "10.0.0",
   "description": "Client for prometheus",
@@ -11,10 +11,11 @@ "main": "index.js",
   ],
-  "directories": {
-    "test": "test"
+  "engines": {
+    "node": ">=4"
   },
   "scripts": {
     "test": "npm run lint && npm run compile-typescript && npm run test-unit",
-    "lint": "node-version-gte-4 && eslint . || node-version-lt-4",
-    "test-unit": "mocha --recursive test/",
-    "compile-typescript": "tsc index.d.ts --noImplicitAny"
+    "lint": "eslint .",
+    "test-unit": "jest",
+    "compile-typescript": "tsc index.d.ts --noImplicitAny",
+    "precommit": "lint-staged"
   },
@@ -34,17 +35,30 @@ "repository": {
   "devDependencies": {
-    "chai": "^3.4.1",
-    "eslint": "^3.5.0",
+    "eslint": "^4.1.1",
+    "eslint-plugin-prettier": "^2.1.2",
     "express": "^4.13.3",
-    "mocha": "^3.2.0",
-    "mockery": "^2.0.0",
-    "nock": "^9.0.11",
-    "node-version-check": "^2.1.1",
-    "sinon": "^2.0.0",
+    "husky": "^0.13.4",
+    "jest": "^20.0.4",
+    "lint-staged": "^4.0.0",
+    "lolex": "^1.6.0",
+    "prettier": "1.5.2",
     "typescript": "^2.0.3"
   },
   "dependencies": {
-    "tdigest": "^0.1.1",
-    "util-extend": "^1.0.1"
+    "tdigest": "^0.1.1"
   },
-  "types": "./index.d.ts"
+  "types": "./index.d.ts",
+  "jest": {
+    "testEnvironment": "node",
+    "testRegex": ".*Test\\.js$"
+  },
+  "lint-staged": {
+    "*.js": [
+      "eslint --fix",
+      "git add"
+    ],
+    "*.ts": [
+      "prettier --write --use-tabs --single-quote",
+      "git add"
+    ]
+  }
 }

README.md

@@ -26,14 +26,27 @@ # Prometheus client for node.js [![Build Status](https://travis-ci.org/siimon/prom-client.svg?branch=master)](https://travis-ci.org/siimon/prom-client) [![Build status](https://ci.appveyor.com/api/projects/status/k2e0gwonkcee3lp9/branch/master?svg=true)](https://ci.appveyor.com/project/siimon/prom-client/branch/master)
 
-The function returned from `collectDefaultMetrics` takes 1 option, a timeout for how often the probe should
-be fired. By default probes are launched every 10 seconds, but this can be modified like this:
+`collectDefaultMetrics` takes 1 options object with 2 entries, a timeout for how often the probe should be fired and a
+registry to which metrics should be registered. By default probes are launched every 10 seconds, but this can be
+modified like this:
 
 ```js
-var client = require('prom-client');
+const client = require('prom-client');
 
-var collectDefaultMetrics = client.collectDefaultMetrics;
+const collectDefaultMetrics = client.collectDefaultMetrics;
 
 // Probe every 5th second.
-collectDefaultMetrics(5000);
+collectDefaultMetrics({ timeout: 5000 });
 ````
 
+To register metrics to another registry, pass it in as `register`:
+
+```js
+const client = require('prom-client');
+
+const collectDefaultMetrics = client.collectDefaultMetrics;
+const Registry = client.Registry;
+const register = new Registry();
+
+collectDefaultMetrics({ register });
+````
+
 You can get the full list of metrics by inspecting `client.collectDefaultMetrics.metricsList`.
@@ -47,7 +60,7 @@
 ```js
-var client = require('prom-client');
+const client = require('prom-client');
 
-var collectDefaultMetrics = client.collectDefaultMetrics;
+const collectDefaultMetrics = client.collectDefaultMetrics;
 
-var interval = collectDefaultMetrics();
+const interval = collectDefaultMetrics();
 
@@ -67,3 +80,3 @@ // ... some time later
 ```js
-var client = require('prom-client');
+const client = require('prom-client');
 
@@ -81,4 +94,4 @@ clearInterval(client.collectDefaultMetrics());
 ```js
-var client = require('prom-client');
-var counter = new client.Counter({ name: 'metric_name', help: 'metric_help' });
+const client = require('prom-client');
+const counter = new client.Counter({ name: 'metric_name', help: 'metric_help' });
 counter.inc(); // Inc with 1
@@ -93,4 +106,4 @@ counter.inc(10); // Inc with 10
 ```js
-var client = require('prom-client');
-var gauge = new client.Gauge({ name: 'metric_name', help: 'metric_help' });
+const client = require('prom-client');
+const gauge = new client.Gauge({ name: 'metric_name', help: 'metric_help' });
 gauge.set(10); // Set to 10
@@ -108,3 +121,3 @@ gauge.inc(); // Inc with 1
 
-var end = gauge.startTimer();
+const end = gauge.startTimer();
 xhrRequest(function(err, res) {
@@ -123,3 +136,3 @@ end(); // Sets value to xhrRequests duration in seconds
 ```js
-var client = require('prom-client');
+const client = require('prom-client');
 new client.Histogram({ name: 'metric_name', help: 'metric_help', buckets: [ 0.10, 5, 15, 50, 100, 500 ] });
@@ -129,3 +142,3 @@ ```
 ```js
-var client = require('prom-client');
+const client = require('prom-client');
 new client.Histogram({ name: 'metric_name', help: 'metric_help', labelNames: [ 'status_code' ], buckets: [ 0.10, 5, 15, 50, 100, 500 ] });
@@ -137,4 +150,4 @@ ```
 ```js
-var client = require('prom-client');
-var histogram = new client.Histogram({ name: 'metric_name', help: 'metric_help' });
+const client = require('prom-client');
+const histogram = new client.Histogram({ name: 'metric_name', help: 'metric_help' });
 histogram.observe(10); // Observe value in histogram
@@ -145,3 +158,3 @@ ```
 ```js
-var end = histogram.startTimer();
+const end = histogram.startTimer();
 xhrRequest(function(err, res) {
@@ -161,3 +174,3 @@ end(); // Observes the value to xhrRequests duration in seconds
 ```js
-var client = require('prom-client');
+const client = require('prom-client');
 new client.Summary({ name: 'metric_name', help: 'metric_help', percentiles: [ 0.01, 0.1, 0.9, 0.99 ] });
@@ -169,4 +182,4 @@ ```
 ```js
-var client = require('prom-client');
-var summary = new client.Summary({ name: 'metric_name', help: 'metric_help' });
+const client = require('prom-client');
+const summary = new client.Summary({ name: 'metric_name', help: 'metric_help' });
 summary.observe(10);
@@ -177,3 +190,3 @@ ```
 ```js
-var end = summary.startTimer();
+const end = summary.startTimer();
 xhrRequest(function(err, res) {
@@ -188,4 +201,4 @@ end(); // Observes the value to xhrRequests duration in seconds
 ```js
-var client = require('prom-client');
-var gauge = new client.Gauge({ name: 'metric_name', help: 'metric_help', labelNames: [ 'method', 'statusCode' ] });
+const client = require('prom-client');
+const gauge = new client.Gauge({ name: 'metric_name', help: 'metric_help', labelNames: [ 'method', 'statusCode' ] });
 
@@ -198,3 +211,3 @@ gauge.set({ method: 'GET', statusCode: '200' }, 100); // 1st version, Set value 100 with method set to GET and statusCode to 200
 ```js
-var end = startTimer({ method: 'GET' }); // Set method to GET, we don't know statusCode yet
+const end = startTimer({ method: 'GET' }); // Set method to GET, we don't know statusCode yet
 xhrRequest(function(err, res) {
@@ -209,2 +222,22 @@ if (err) {
 
+##### Default Labels (segmented by registry)
+
+Static labels may be applied to every metric emitted by a registry:
+```js
+const client = require('prom-client');
+const defaultLabels = { serviceName: "api-v1" };
+client.register.setDefaultLabels(defaultLabels);
+```
+
+This will output metrics in the following way:
+```
+# HELP process_resident_memory_bytes Resident memory size in bytes.
+# TYPE process_resident_memory_bytes gauge
+process_resident_memory_bytes{serviceName="api-v1"} 33853440 1498510040309
+```
+
+Default labels will be overridden if there is a name conflict.
+
+`register.clear()` will clear default labels.
+
 #### Timestamps
@@ -237,10 +270,10 @@
 ```js
-var client = require('prom-client');
-var registry = new client.Registry();
-var counter = new client.Counter({name: 'metric_name', help: 'metric_help', registers: [ registry ]});
-var histogram = new client.Histogram({name: 'metric_name', help: 'metric_help', registers: [ ]});
+const client = require('prom-client');
+const registry = new client.Registry();
+const counter = new client.Counter({name: 'metric_name', help: 'metric_help', registers: [ registry ]});
+const histogram = new client.Histogram({name: 'metric_name', help: 'metric_help', registers: [ ]});
 registry.registerMetric(histogram);
 counter.inc();
 
-var mergedRegistries = client.Registry.merge([registry, client.register]);
+const mergedRegistries = client.Registry.merge([registry, client.register]);
 ```
@@ -252,3 +285,3 @@
 
-##### Geting a single metric for Prometheus displaying
+##### Getting a single metric for Prometheus displaying
 
@@ -271,4 +304,4 @@ If you need to output a single metric for Prometheus, you can use `register.getSingleMetricAsString(*name of metric*)`, it will output a string for Prometheus to consume.
 ```js
-var client = require('prom-client');
-var gateway = new client.Pushgateway('http://127.0.0.1:9091');
+const client = require('prom-client');
+let gateway = new client.Pushgateway('http://127.0.0.1:9091');
 
@@ -292,3 +325,3 @@ gateway.pushAdd({ jobName: 'test' }, function(err, resp, body) { }); //Add metric and overwrite old ones
 ```js
-var client = require('prom-client');
+const client = require('prom-client');
 new client.Histogram({
@@ -295,0 +328,0 @@ name: 'metric_name',

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• - Removedutil-extend@^1.0.1

• - Removedutil-extend@1.0.3(transitive)