Set aggregation method for newer event loop metrics

These are not entirely accurate: they're the "mean of the mean" and "mean of percentiles," but that's as good as we can get.

Fixes #418

CHANGELOG.md

@@ -16,6 +16,7 @@ project adheres to [Semantic Versioning](http://semver.org/).
 - fix: push client attempting to write Promise
 - types: improve type checking of labels
 - fix: Summary#observe should throw when adding additional labels to labelset (fixes [#262](https://github.com/siimon/prom-client/issues/262))
+- fix: Set aggregation mode for newer event loop metrics. (Fixes [#418](https://github.com/siimon/prom-client/issues/418))
 
 ### Added
 

lib/metrics/eventLoopLag.js

@@ -77,42 +77,49 @@ module.exports = (registry, config = {}) => {
 		help: 'The minimum recorded event loop delay.',
 		registers,
 		labelNames,
+		aggregator: 'min',
 	});
 	const lagMax = new Gauge({
 		name: namePrefix + NODEJS_EVENTLOOP_LAG_MAX,
 		help: 'The maximum recorded event loop delay.',
 		registers,
 		labelNames,
+		aggregator: 'max',
 	});
 	const lagMean = new Gauge({
 		name: namePrefix + NODEJS_EVENTLOOP_LAG_MEAN,
 		help: 'The mean of the recorded event loop delays.',
 		registers,
 		labelNames,
+		aggregator: 'average',
 	});
 	const lagStddev = new Gauge({
 		name: namePrefix + NODEJS_EVENTLOOP_LAG_STDDEV,
 		help: 'The standard deviation of the recorded event loop delays.',
 		registers,
 		labelNames,
+		aggregator: 'average',
 	});
 	const lagP50 = new Gauge({
 		name: namePrefix + NODEJS_EVENTLOOP_LAG_P50,
 		help: 'The 50th percentile of the recorded event loop delays.',
 		registers,
 		labelNames,
+		aggregator: 'average',
 	});
 	const lagP90 = new Gauge({
 		name: namePrefix + NODEJS_EVENTLOOP_LAG_P90,
 		help: 'The 90th percentile of the recorded event loop delays.',
 		registers,
 		labelNames,
+		aggregator: 'average',
 	});
 	const lagP99 = new Gauge({
 		name: namePrefix + NODEJS_EVENTLOOP_LAG_P99,
 		help: 'The 99th percentile of the recorded event loop delays.',
 		registers,
 		labelNames,
+		aggregator: 'average',
 	});
 };