[es/healthcheck] ensure that healthcheck stops when server is stopped (#13201)

src/core_plugins/elasticsearch/lib/__tests__/health_check.js

@@ -21,8 +21,13 @@ describe('plugins/elasticsearch', () => {
     let health;
     let plugin;
     let cluster;
+    let server;
     const sandbox = sinon.sandbox.create();
 
+    function getTimerCount() {
+      return Object.keys(sandbox.clock.timers || {}).length;
+    }
+
     beforeEach(() => {
       const COMPATIBLE_VERSION_NUMBER = '5.0.0';
 
@@ -66,7 +71,7 @@ describe('plugins/elasticsearch', () => {
       const set = sinon.stub();
 
       // Setup the server mock
-      const server = {
+      server = {
         log: sinon.stub(),
         info: { port: 5601 },
         config: function () { return { get, set }; },
@@ -77,7 +82,8 @@ describe('plugins/elasticsearch', () => {
         },
         getKibanaIndexMappingsDsl() {
           return mappings;
-        }
+        },
+        ext: sinon.stub()
       };
 
       health = healthCheck(plugin, server);
@@ -85,6 +91,28 @@ describe('plugins/elasticsearch', () => {
 
     afterEach(() => sandbox.restore());
 
+    it('should stop when cluster is shutdown', () => {
+      sandbox.useFakeTimers();
+
+      // ensure that health.start() is responsible for the timer we are observing
+      expect(getTimerCount()).to.be(0);
+      health.start();
+      expect(getTimerCount()).to.be(1);
+
+      // ensure that a server extension was registered
+      sinon.assert.calledOnce(server.ext);
+      sinon.assert.calledWithExactly(server.ext, sinon.match.string, sinon.match.func);
+
+      // call the server extension
+      const reply = sinon.stub();
+      const [,handler] = server.ext.firstCall.args;
+      handler({}, reply);
+
+      // ensure that the handler called reply and unregistered the time
+      sinon.assert.calledOnce(reply);
+      expect(getTimerCount()).to.be(0);
+    });
+
     it('should set the cluster green if everything is ready', function () {
       cluster.callWithInternalUser.withArgs('ping').returns(Promise.resolve());
       cluster.callWithInternalUser.withArgs('cluster.health', sinon.match.any).returns(

src/core_plugins/elasticsearch/lib/health_check.js

@@ -145,6 +145,11 @@ export default function (plugin, server) {
     return true;
   }
 
+  server.ext('onPreStop', (request, reply) => {
+    stopChecking();
+    reply();
+  });
+
   return {
     waitUntilReady: waitUntilReady,
     run: check,