@emartech/aggregate-metric-logger

aggregate-metric-logger

aggregate metrics in memory and log them every minute

Setup

Set METRIC_LOGGER_ENABLED env variable to true for aggregate-metric-logger to start collecting and logging measuremnts.

To change the default aggregate-metric-logger namespace used for logs, set METRIC_LOGGER_NAMESPACE to a custom value.

Usage

The package exposes similar logging methods as the @emartech/json-logger package: trace, debug, info, warn, error and fatal.

When these are called, it will aggregate logs with the same parameters withing a minute, add an extra count property to the logs and log them at the end of the minute with @emartech/json-logger.

const metrictLogger = require('aggregate-metric-logger')

metricLogger.warn('etwas-went-wrong', { customer_id: 11 });
metricLogger.warn('etwas-went-wrong', { customer_id: 11 });

// will aggrete these to a single warning log

Measure values

If you want aggregate measuremts about something you need to simply call the measure method for each value:

const metrictLogger = require('aggregate-metric-logger')

metricLogger.measure('thing-to-measure', 14)
metricLogger.measure('thing-to-measure', 20)

Every minute metric logger will log min, max, sum, count and average aggregated metrics for each measured tags. (Uses @emartech/json-logger behind the scenes for logging).

Measuring durations

For duration measuremts, there are two convinience methods: start, and stop;

You start the measurement with start, the counted value for aggregation will be the duration between this start and the matcing stop call;

function exampleIOHeavyFunction() {
  const measurementId = metricLogger.start('tag-for-the-measuement');
  const result = db.findItems();
  metricLogger.stop(measurementId);
  return result;
}

Group by extra parameters

If you want to group by additional parameters inside a tag, you can pass down these extra params in an object to count and start as the last optional argument:

metricLogger.count('thing-to-count', 14, { customer_id: 12 });

const measurementId = metricLogger.start(
  'tag-for-the-measuement',
  { event_type: 'nyul', account: 3 }
);

A separete log entry will be created for each seen value combinations seen in the extra params and these extra params will appended to the log entry.

Be very carefull when using extra params, and only include information you really need. If you include too many parameters, you could loose the advantage you gain by aggregating your logs with this package.