Remove the Service Metrics alert

This removes the annoying alert when a service is not recognised. This
causes a lot of churn and there's no need for it. next-metrics now
guesses the service name based on the request URL's host name
(Financial-Times/next-metrics#583) and so this
alert will never fire.

This also allows us to do a lot of simplification because we don't have
to handle undefined services.

For all the removed things (e.g. types/options):
a) these was never part of the public API for n-express
b) we don't seem to be using them anywhere

See-also: https://financialtimes.atlassian.net/browse/CPREL-1123

main.js

@@ -23,7 +23,6 @@ const consentMiddleware = require('./src/middleware/consent');
 
 // logging and monitoring
 const metrics = require('next-metrics');
-const serviceMetrics = require('./src/lib/service-metrics');
 const logger = require('@dotcom-reliability-kit/logger');
 
 // utils
@@ -132,7 +131,7 @@ const getAppContainer = (options) => {
 	);
 
 	if (options.withServiceMetrics) {
-		instrumentListen.addMetrics(serviceMetrics.init());
+		metrics.fetch.instrument();
 	}
 
 	if (options.withBackendAuthentication) {

package.json

@@ -20,7 +20,7 @@
     "express": "^4.17.3",
     "isomorphic-fetch": "^3.0.0",
     "n-health": "^13.0.0",
-    "next-metrics": "^12.12.0",
+    "next-metrics": "^12.15.0",
     "semver": "^7.3.7"
   },
   "devDependencies": {

src/lib/health-checks.js

@@ -10,7 +10,6 @@ const logger = require('@dotcom-reliability-kit/logger');
 const herokuLogDrainCheck = require('./heroku-log-drain-check');
 const metricsHealthCheck = require('./metrics-healthcheck');
 const supportedNodeJsVersionCheck = require('./supported-node-js-version-check');
-const unRegisteredServicesHealthCheck = require('./unregistered-services-healthCheck');
 
 /**
  * @param {ExpressApp} app
@@ -34,7 +33,6 @@ module.exports = (app, options, meta) => {
 	/** @type {Healthcheck[]} */
 	const defaultChecks = [
 		...tickingMetricChecks,
-		unRegisteredServicesHealthCheck.setAppName(meta.name),
 		metricsHealthCheck(meta.name),
 		supportedNodeJsVersionCheck(meta.name)
 	];

test/app/clear-interval.test.js

@@ -3,16 +3,9 @@ const nextExpress = require('../../main');
 const InstrumentListen = require('../../src/lib/instrument-listen');
 const expect = require('chai').expect;
 const healthChecks = require('../../src/lib/health-checks');
-const serviceMetrics = require('../../src/lib/service-metrics');
 const sinon = require('sinon');
 
 describe('clears intervals', () => {
-	it('should return object with stop function in service-metrics', () => {
-		const result = serviceMetrics.init();
-		expect(result.stop).to.not.be.undefined;
-		result.stop();
-	});
-
 	it('should return an array of objects with stop functions in health-checks', () => {
 		const app = express();
 
@@ -29,21 +22,6 @@ describe('clears intervals', () => {
 		}, 0);
 	});
 
-	it('should call stop() which clears all intervals if a metric is added to instrumentListen', () => {
-		const app = express();
-		const instrumentListen = new InstrumentListen(app, {}, []);
-		const spy = sinon.spy();
-		const stub = sinon.stub(serviceMetrics, 'init');
-		stub.returns({
-			stop: spy
-		});
-		instrumentListen.addMetrics(serviceMetrics.init());
-
-		app.close();
-
-		expect(spy.called).to.be.true;
-	});
-
 	it('should close server in app.close if there is a live server', () => {
 		const app = express();
 		const instrumentListen = new InstrumentListen(app, {}, [Promise.resolve()]);

typings/metrics.d.ts

@@ -17,8 +17,3 @@ export type TickingMetric = {
 export type Healthcheck = {
 	getStatus: () => HealthcheckStatus;
 };
-
-export interface InitHealthCheck {
-	setAppName: (appName: string) => Metrics.Healthcheck;
-	updateCheck: (unregisteredServices: Record<string, any>) => void;
-}