database-metrics-logger

Database Metrics Logger

❯ Why

You want to log service metrics from your application on Cloud Foundry? - Yes? - Here you are 🙌 !!

❯ Table of Contents

• Supported Services
• Quick Start
• API
• Cloud Connectors
• Development
• Project Structure

❯ Supported Services

Service	Version
MongoDB	>=3.6.6
Redis	>=2.3.9

❯ Quick Start

Installation

Install library by using npm

npm install database-metrics-logger

or by using yarn

yarn add database-metrics-logger

How to use

Step 1: Import DatabaseMetricsLogger

Using CommonJS module loader:

const DatabaseMetricsLogger = require('database-metrics-logger');

Using ES6 module loader:

import { DatabaseMetricsLogger } from 'database-metrics-logger';

Step 2: Create new instance of CfServiceMetricsLogger

Create new instance of DatabaseMetricsLogger and provide options:

const credentials = [
  {
    databaseType: 'mongodb',
    host: 'your-mongodb-host',
    username: 'user',
    password: 'this-is-secret',
    port: 27017
    database: mongodbCredentials.database,
  },
  {
    databaseType: 'redis',
    host: 'your-redis-host',
    port: 6379,
    password: 'this-is-secret',
  }
];

const databaseMetricsLogger = new DatabaseMetricsLogger(credentials);

Step 3: Subscribe to receive service metrics and general logs

Subscribe metrics to receive service metrics data:

databaseMetricsLogger.subscribe('metrics', data => {
  // do some fancy stuff with your metrics
});

Subscribe logs to receive general application logs:

databaseMetricsLogger.subscribe('logs', {message, level} => {
  console[level](message));
});

Step 3: Start and stop service metrics logging

Start database metrics logging:

databaseMetricsLogger.start();

Stop service metrics logging:

databaseMetricsLogger.stop();

❯ API

Credentials Options

Option	Description	Default Value
databaseType	Type of database. Currently only mongodb redis are available
host	Host of database
port (optional)	Port of database
uri (optional)	Instead of port and host, you can provide an URI
username (optional)	Username
password (optional)	Password
interval (optional)	Database metrics polling interval in ms	10000

Methods

Method	Description
start()	Start service metrics
stop()	Stop service metrics
subscribe(eventId, callback)	Subscribe an event
unsubscribe(eventId, callback)	Unsubscribe an event
unsubscribeAll()	Unsubscribe all events

Subscription event id's

Id	Description
metrics	Service metrics
logs	General application logs for levels debug, info, warn and error

❯ Cloud Connectors

You can use a cloud connector to log metrics from your cloud instance databases.

Cloud Foundry

Options

Option	Description	Default Value
vcap (optional)	Provide local VCAP_SERVICES and/or VCAP_APPLICATION values	{}
vcapFile (optional)	Provide local VCAP_SERVICES and/or VCAP_APPLICATION file	''

Methods

Method	Description
getCredentials()	Get Cloud Foundry service credentials

Example

// import using `CommonJS` module loader:
const { CloudFoundryConnector, DatabaseMetricsLogger } = require('cf-service-metrics-logger');

// or import using `ES6` module loader:
import { CloudFoundryConnector, DatabaseMetricsLogger } from 'cf-service-metrics-logger';

const options = {
  vcapFile: 'your-vcap-file-path/vcap.json' 
};

const cloudFoundryConnector = new CloudFoundryConnector(options);
const credentials = cloudFoundryConnector.getCredentials();
const databaseMetricsLogger = new DatabaseMetricsLogger(credentials);

databaseMetricsLogger.subscribe('metrics', data => {
  // do some fancy stuff with your metrics
});

databaseMetricsLogger.start();

setTimeout(() => {
  databaseMetricsLogger.stop();
}, 30000);

❯ Development

Getting Started

Step 1: Set up the Development Environment

You need to set up your development environment before you can do anything.

Install Node.js and NPM

• on OSX use homebrew brew install node
• on Windows use chocolatey choco install nodejs

Install yarn globally

yarn install yarn -g

Step 2: Install dependencies

Install all dependencies with yarn.

yarn install

Scripts and Tasks

Install

• Install all dependencies with yarn install

Linting

• Run code quality analysis using yarn run lint. This runs tslint.

Tests

• Run unit test using yarn run test.

Building the project

• Run yarn run build to generate commonJS and ES6 modules as well as declaration from the TypeScript source.
• Builded sources are located in dist folder.

Debugger

VS Code

Just set a breakpoint in source or unit test and hit F5 in your Visual Studio Code to execute and debug all unit tests.

❯ Project Structure

Name	Description
.vscode/	VSCode tasks, launch configuration and some other settings
dist/	Compiled and bundled source files will be placed here
src/	Source files
src/types/ *.d.ts	Custom type definitions and files that aren't on DefinitelyTyped
test/	Tests
test/unit/ *.test.ts	Unit tests
rollup.config.js	Config for Rollup module bundler