feat(metrics): update prom-client for more dimensions

also removes the need for gc-stats, using the Node.JS API instead

__tests__/integration/__snapshots__/one-app.spec.js.snap

@@ -50,11 +50,16 @@ Array [
   "nodejs_active_handles_total",
   "nodejs_active_requests",
   "nodejs_active_requests_total",
+  "nodejs_eventloop_lag_max_seconds",
+  "nodejs_eventloop_lag_mean_seconds",
+  "nodejs_eventloop_lag_min_seconds",
+  "nodejs_eventloop_lag_p50_seconds",
+  "nodejs_eventloop_lag_p90_seconds",
+  "nodejs_eventloop_lag_p99_seconds",
   "nodejs_eventloop_lag_seconds",
+  "nodejs_eventloop_lag_stddev_seconds",
   "nodejs_external_memory_bytes",
-  "nodejs_gc_pause_seconds_total",
-  "nodejs_gc_reclaimed_bytes_total",
-  "nodejs_gc_runs_total",
+  "nodejs_gc_duration_seconds",
   "nodejs_heap_size_total_bytes",
   "nodejs_heap_size_used_bytes",
   "nodejs_heap_space_size_available_bytes",

__tests__/server/metricsServer.spec.js

@@ -21,27 +21,17 @@ describe('metricsServer', () => {
   jest.spyOn(console, 'warn').mockImplementation(() => {});
 
   let client;
-  let promGcStats;
   let healthCheck;
   let logging;
 
-  function load({ gcStatsError = false } = {}) {
+  function load() {
     jest.resetModules();
 
     jest.mock('prom-client');
-    if (gcStatsError) {
-      jest.mock('gc-stats', () => {
-        throw new Error('unable to resolve gc-stats');
-      }, { virtual: true });
-    } else {
-      jest.mock('gc-stats', () => jest.fn(), { virtual: true });
-    }
-    jest.mock('prometheus-gc-stats', () => jest.fn(() => () => {}));
     jest.mock('../../src/server/utils/logging/serverMiddleware', () => jest.fn((req, res, next) => next()));
     jest.mock('../../src/server/middleware/healthCheck');
 
     client = require('prom-client');
-    promGcStats = require('prometheus-gc-stats');
     logging = require('../../src/server/utils/logging/serverMiddleware');
     healthCheck = require('../../src/server/middleware/healthCheck').default;
 
@@ -53,25 +43,6 @@ describe('metricsServer', () => {
       load();
       expect(client.collectDefaultMetrics).toHaveBeenCalledTimes(1);
     });
-
-    it('collects default metrics every ten seconds', () => {
-      load();
-      expect(client.collectDefaultMetrics).toHaveBeenCalledTimes(1);
-      expect(client.collectDefaultMetrics.mock.calls[0][0]).toHaveProperty('timeout', 10 * 1e3);
-    });
-
-    it('collects garbage collection metrics', () => {
-      load();
-      expect(promGcStats).toHaveBeenCalledTimes(1);
-      expect(promGcStats).toHaveBeenCalledWith(client.register);
-    });
-
-    it('warns if unable to collect garbage collection metrics', () => {
-      console.warn.mockClear();
-      load({ gcStatsError: true });
-      expect(console.warn).toHaveBeenCalledTimes(1);
-      expect(console.warn.mock.calls[0]).toMatchSnapshot();
-    });
   });
 
   describe('unknown routes', () => {

package.json

@@ -101,8 +101,7 @@
     "opossum": "^5.0.0",
     "opossum-prometheus": "^0.1.0",
     "pidusage": "^2.0.17",
-    "prom-client": "^11.5.3",
-    "prometheus-gc-stats": "^0.6.2",
+    "prom-client": "^12.0.0",
     "prop-types": "^15.7.2",
     "react": "^16.13.1",
     "react-dom": "^16.13.1",
@@ -181,7 +180,6 @@
     }
   },
   "optionalDependencies": {
-    "gc-stats": "^1.4.0",
     "heapdump": "^0.3.15"
   },
   "standard-version": {

src/server/metricsServer.js

@@ -17,24 +17,11 @@
 import express from 'express';
 import helmet from 'helmet';
 import { register as metricsRegister, collectDefaultMetrics } from 'prom-client';
-import gcStats from 'prometheus-gc-stats';
 
 import logging from './utils/logging/serverMiddleware';
 import healthCheck from './middleware/healthCheck';
 
-// Probe every 10th second.
-collectDefaultMetrics({ timeout: 10e3 });
-gcStats(metricsRegister)();
-
-// prometheus-gc-stats uses gc-stats but swallows the error if not importable
-// try importing ourselves so we can log a warning
-try {
-  /* eslint import/no-extraneous-dependencies: ["error", {"optionalDependencies": true}] */
-  // eslint-disable-next-line global-require, import/no-unresolved
-  require('gc-stats');
-} catch (err) {
-  console.warn('Unable to set up garbage collection monitor. This is not an issue for local development.');
-}
+collectDefaultMetrics();
 
 export function createMetricsServer() {
   const app = express();