feat: add stop() method to gracefully terminate unleash (#665)

lib/db/client-instance-store.js

@@ -38,7 +38,7 @@ class ClientInstanceStore {
             });
         const clearer = () => this._removeInstancesOlderThanTwoDays();
         setTimeout(clearer, 10).unref();
-        setInterval(clearer, ONE_DAY).unref();
+        this.timer = setInterval(clearer, ONE_DAY).unref();
     }
 
     async _removeInstancesOlderThanTwoDays() {
@@ -133,6 +133,10 @@ class ClientInstanceStore {
             .where('app_name', appName)
             .del();
     }
+
+    destroy() {
+        clearInterval(this.timer);
+    }
 }
 
 module.exports = ClientInstanceStore;

lib/db/client-metrics-db.js

@@ -19,7 +19,7 @@ class ClientMetricsDb {
         // Clear old metrics regulary
         const clearer = () => this.removeMetricsOlderThanOneHour();
         setTimeout(clearer, 10).unref();
-        setInterval(clearer, ONE_MINUTE).unref();
+        this.timer = setInterval(clearer, ONE_MINUTE).unref();
     }
 
     async removeMetricsOlderThanOneHour() {
@@ -60,6 +60,10 @@ class ClientMetricsDb {
 
         return result.map(mapRow);
     }
+
+    destroy() {
+        clearInterval(this.timer);
+    }
 }
 
 module.exports = ClientMetricsDb;

lib/db/client-metrics-store.js

@@ -62,11 +62,8 @@ class ClientMetricsStore extends EventEmitter {
     }
 
     destroy() {
-        try {
         clearInterval(this.timer);
-        } catch (e) {
-            // empty
-        }
+        this.metricsDb.destroy();
     }
 }
 

lib/db/client-metrics-store.test.js

@@ -20,6 +20,9 @@ function getMockDb() {
         getNewMetrics() {
             return Promise.resolve([list.pop() || { id: 0 }]);
         },
+        destroy() {
+            // noop
+        },
     };
 }
 

lib/metrics.js

@@ -11,7 +11,12 @@ const {
 
 const THREE_HOURS = 3 * 60 * 60 * 1000;
 
-exports.startMonitoring = ({ serverMetrics, eventBus, stores, version }) => {
+class MetricsMonitor {
+    constructor() {
+        this.timer = null;
+    }
+
+    startMonitoring({ serverMetrics, eventBus, stores, version }) {
         if (!serverMetrics) {
             return;
         }
@@ -55,11 +60,17 @@ exports.startMonitoring = ({ serverMetrics, eventBus, stores, version }) => {
         }
 
         collectFeatureToggleMetrics();
-    setInterval(() => collectFeatureToggleMetrics(), THREE_HOURS);
+        this.timer = setInterval(
+            () => collectFeatureToggleMetrics(),
+            THREE_HOURS,
+        ).unref();
 
-    eventBus.on(events.REQUEST_TIME, ({ path, method, time, statusCode }) => {
+        eventBus.on(
+            events.REQUEST_TIME,
+            ({ path, method, time, statusCode }) => {
                 requestDuration.labels(path, method, statusCode).observe(time);
-    });
+            },
+        );
 
         eventBus.on(events.DB_TIME, ({ store, action, time }) => {
             dbDuration.labels(store, action).observe(time);
@@ -80,9 +91,26 @@ exports.startMonitoring = ({ serverMetrics, eventBus, stores, version }) => {
 
         clientMetricsStore.on('metrics', m => {
             // eslint-disable-next-line no-restricted-syntax
-        for (const [feature, { yes, no }] of Object.entries(m.bucket.toggles)) {
-            featureToggleUsageTotal.labels(feature, true, m.appName).inc(yes);
-            featureToggleUsageTotal.labels(feature, false, m.appName).inc(no);
+            for (const [feature, { yes, no }] of Object.entries(
+                m.bucket.toggles,
+            )) {
+                featureToggleUsageTotal
+                    .labels(feature, true, m.appName)
+                    .inc(yes);
+                featureToggleUsageTotal
+                    .labels(feature, false, m.appName)
+                    .inc(no);
             }
         });
+    }
+
+    stopMonitoring() {
+        clearInterval(this.timer);
+    }
+}
+
+module.exports = {
+    createMetricsMonitor() {
+        return new MetricsMonitor();
+    },
 };

lib/metrics.test.js

@@ -9,7 +9,9 @@ const clientMetricsStore = new EventEmitter();
 const { register: prometheusRegister } = require('prom-client');
 const { REQUEST_TIME, DB_TIME } = require('./events');
 const { FEATURE_UPDATED } = require('./event-type');
-const { startMonitoring } = require('./metrics');
+const { createMetricsMonitor } = require('./metrics');
+
+const monitor = createMetricsMonitor();
 
 test.before(() => {
     const featureToggleStore = {
@@ -25,7 +27,11 @@ test.before(() => {
         },
         version: '3.4.1',
     };
-    startMonitoring(config);
+    monitor.startMonitoring(config);
+});
+
+test.after(() => {
+    monitor.stopMonitoring();
 });
 
 test('should collect metrics for requests', t => {

lib/server-impl.js

@@ -5,7 +5,7 @@ const { EventEmitter } = require('events');
 const migrator = require('../migrator');
 const getApp = require('./app');
 
-const { startMonitoring } = require('./metrics');
+const { createMetricsMonitor } = require('./metrics');
 const { createStores } = require('./db');
 const { createServices } = require('./services');
 const { createOptions } = require('./options');
@@ -15,6 +15,27 @@ const AuthenticationRequired = require('./authentication-required');
 const { addEventHook } = require('./event-hook');
 const eventType = require('./event-type');
 
+async function closeServer(opts) {
+    const { server, metricsMonitor } = opts;
+
+    metricsMonitor.stopMonitoring();
+
+    return new Promise((resolve, reject) => {
+        server.close(err => (err ? reject(err) : resolve()));
+    });
+}
+
+async function destroyDatabase(stores) {
+    const { db, clientInstanceStore, clientMetricsStore } = stores;
+
+    return new Promise((resolve, reject) => {
+        clientInstanceStore.destroy();
+        clientMetricsStore.destroy();
+
+        db.destroy(error => (error ? reject(error) : resolve()));
+    });
+}
+
 async function createApp(options) {
     // Database dependencies (stateful)
     const logger = options.getLogger('server-impl.js');
@@ -33,7 +54,8 @@ async function createApp(options) {
     };
 
     const app = getApp(config);
-    startMonitoring(config);
+    const metricsMonitor = createMetricsMonitor();
+    metricsMonitor.startMonitoring(config);
 
     if (typeof config.eventHook === 'function') {
         addEventHook(config.eventHook, stores.eventStore);
@@ -61,14 +83,28 @@ async function createApp(options) {
             const server = app.listen(options.listen, () =>
                 logger.info('Unleash has started.', server.address()),
             );
+            const stop = () => {
+                logger.info('Shutting down Unleash...');
+
+                return closeServer({ server, metricsMonitor }).then(() => {
+                    return destroyDatabase(stores);
+                });
+            };
+
             server.keepAliveTimeout = options.keepAliveTimeout;
             server.headersTimeout = options.headersTimeout;
             server.on('listening', () => {
-                resolve({ ...payload, server });
+                resolve({ ...payload, server, stop });
             });
             server.on('error', reject);
         } else {
-            resolve({ ...payload });
+            const stop = () => {
+                logger.info('Shutting down Unleash...');
+                metricsMonitor.stopMonitoring();
+                return destroyDatabase(stores);
+            };
+
+            resolve({ ...payload, stop });
         }
     });
 }

lib/server-impl.test.js

@@ -14,6 +14,8 @@ const getApp = proxyquire('./app', {
     },
 });
 
+const noop = () => {};
+
 const eventStore = new EventEmitter();
 const settingStore = {
     get: () => {
@@ -24,13 +26,19 @@ const settingStore = {
 const serverImpl = proxyquire('./server-impl', {
     './app': getApp,
     './metrics': {
-        startMonitoring(o) {
-            return o;
+        createMetricsMonitor() {
+            return {
+                startMonitoring: noop,
+                stopMonitoring: noop,
+            };
         },
     },
     './db': {
         createStores() {
             return {
+                db: { destroy: cb => cb() },
+                clientInstanceStore: { destroy: noop },
+                clientMetricsStore: { destroy: noop },
                 eventStore,
                 settingStore,
             };
@@ -99,3 +107,13 @@ test('should not create a server using create()', async t => {
     });
     t.true(typeof server === 'undefined');
 });
+
+test.only('should shutdown the server when calling stop()', async t => {
+    const { server, stop } = await serverImpl.start({
+        port: 0,
+        getLogger,
+        start: true,
+    });
+    await stop();
+    t.is(server.address(), null);
+});