added event support

jquatier · May 2, 2016 · be13288 · be13288
1 parent bf7fc60
commit be13288
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diff --git a/CHANGES.md b/CHANGES.md
@@ -1,3 +1,4 @@
 ## 3.0.0
+  - Added support for the following events: `started`, `registered`, `deregistered`, `heartbeat`, and `registryUpdated`.
   - Improved the stability of the client when it encounters downstream DNS errors, as a side-effect the callback for `fetchRegistries()` now returns errors when they are encountered.
   - Populate registry cache with instances that have a status of `UP`, `filterUpInstances` can be set to `false` to disable.
diff --git a/README.md b/README.md
@@ -137,6 +137,18 @@ option | default value | description
 `eureka.fetchMetadata` | `true` | fetch AWS metadata when in AWS environment, see [Configuring for AWS environments](#configuring-for-aws-environments)
 `eureka.useLocalMetadata` | `false` | use local IP and local hostname from metadata when in an AWS environment.
 
+## Events
+
+Eureka client is an instance of `EventEmitter` and provides the following events for consumption:
+
+event | data provided | description
+---- | --- | ---
+`started` | N/A | Fired when eureka client is fully registered and all registries have been updated.
+`registered` | N/A | Fired when the eureka client is registered with eureka.
+`deregistered` | N/A | Fired when the eureka client is deregistered with eureka.
+`heartbeat` | N/A | Fired when the eureka client has successfully renewed it's lease with eureka.
+`registryUpdated` | N/A | Fired when the eureka client has successfully update it's registries.
+
 ## Debugging
 
 The library uses [request](https://github.com/request/request) for all service calls, and debugging can be turned on by passing `NODE_DEBUG=request` when you start node. This allows you you double-check the URL being called as well as other request properties.

diff --git a/src/EurekaClient.js b/src/EurekaClient.js
@@ -5,6 +5,7 @@ import merge from 'deepmerge';
 import path from 'path';
 import dns from 'dns';
 import { series } from 'async';
+import { EventEmitter } from 'events';
 
 import AwsMetadata from './AwsMetadata';
 import Logger from './Logger';
@@ -28,9 +29,10 @@ function getYaml(file) {
   return yml;
 }
 
-export default class Eureka {
+export default class Eureka extends EventEmitter {
 
   constructor(config = {}) {
+    super();
     // Allow passing in a custom logger:
     this.logger = config.logger || new Logger();
 
@@ -134,6 +136,7 @@ export default class Eureka {
       },
     ], (err, ...rest) => {
       if (err) this.logger.warn('Error starting the Eureka Client', err);
+      this.emit('started');
       callback(err, ...rest);
     });
   }
@@ -189,6 +192,7 @@ export default class Eureka {
             'registered with eureka: ',
             `${this.config.instance.app}/${this.instanceId}`
           );
+          this.emit('registered');
           return callback(null);
         } else if (error) {
           this.logger.warn('Error registering with eureka client.', error);
@@ -216,6 +220,7 @@ export default class Eureka {
             'de-registered with eureka: ',
             `${this.config.instance.app}/${this.instanceId}`
           );
+          this.emit('deregistered');
           return callback(null);
         } else if (error) {
           this.logger.warn('Error deregistering with eureka', error);
@@ -250,6 +255,7 @@ export default class Eureka {
       }, (error, response, body) => {
         if (!error && response.statusCode === 200) {
           this.logger.debug('eureka heartbeat success');
+          this.emit('heartbeat');
         } else if (!error && response.statusCode === 404) {
           this.logger.warn('eureka heartbeat FAILED, Re-registering app');
           this.register();
@@ -322,6 +328,7 @@ export default class Eureka {
         if (!error && response.statusCode === 200) {
           this.logger.debug('retrieved registry successfully');
           this.transformRegistry(JSON.parse(body));
+          this.emit('registryUpdated');
           return callback(null);
         } else if (error) {
           this.logger.warn('Error fetching registry', error);

diff --git a/test/EurekaClient.test.js b/test/EurekaClient.test.js
@@ -3,6 +3,7 @@ import sinon from 'sinon';
 import chai, { expect } from 'chai';
 import sinonChai from 'sinon-chai';
 import request from 'request';
+import { EventEmitter } from 'events';
 import dns from 'dns';
 import { join } from 'path';
 import merge from 'deepmerge';
@@ -29,6 +30,10 @@ function makeConfig(overrides = {}) {
 
 describe('Eureka client', () => {
   describe('Eureka()', () => {
+    it('should extend EventEmitter', () => {
+      expect(new Eureka(makeConfig())).to.be.instanceof(EventEmitter);
+    });
+
     it('should throw an error if no config is found', () => {
       function fn() {
         return new Eureka();
@@ -131,12 +136,16 @@ describe('Eureka client', () => {
       fetchRegistrySpy = sinon.stub(client, 'fetchRegistry').callsArg(0);
       heartbeatsSpy = sinon.stub(client, 'startHeartbeats');
       registryFetchSpy = sinon.stub(client, 'startRegistryFetches');
+      const eventSpy = sinon.spy();
+      client.on('started', eventSpy);
 
       client.start(() => {
         expect(registerSpy).to.have.been.calledOnce;
         expect(fetchRegistrySpy).to.have.been.calledOnce;
         expect(heartbeatsSpy).to.have.been.calledOnce;
         expect(registryFetchSpy).to.have.been.calledOnce;
+        expect(registryFetchSpy).to.have.been.calledOnce;
+        expect(eventSpy).to.have.been.calledOnce;
         done();
       });
     });
@@ -228,6 +237,13 @@ describe('Eureka client', () => {
     afterEach(() => {
       request.post.restore();
     });
+    it('should trigger register event', () => {
+      sinon.stub(request, 'post').yields(null, { statusCode: 204 }, null);
+      const eventSpy = sinon.spy();
+      client.on('registered', eventSpy);
+      client.register();
+      expect(eventSpy).to.have.been.calledOnce;
+    });
 
     it('should call register URI', () => {
       sinon.stub(request, 'post').yields(null, { statusCode: 204 }, null);
@@ -283,6 +299,14 @@ describe('Eureka client', () => {
       request.del.restore();
     });
 
+    it('should should trigger deregister event', () => {
+      sinon.stub(request, 'del').yields(null, { statusCode: 200 }, null);
+      const eventSpy = sinon.spy();
+      client.on('deregistered', eventSpy);
+      client.register();
+      client.deregister();
+    });
+
     it('should call deregister URI', () => {
       sinon.stub(request, 'del').yields(null, { statusCode: 200 }, null);
       const deregisterCb = sinon.spy();
@@ -335,6 +359,15 @@ describe('Eureka client', () => {
       });
     });
 
+    it('should trigger a heartbeat event', () => {
+      sinon.stub(request, 'put').yields(null, { statusCode: 200 }, null);
+      const eventSpy = sinon.spy();
+      client.on('heartbeat', eventSpy);
+      client.renew();
+
+      expect(eventSpy).to.have.been.calledOnce;
+    });
+
     it('should re-register on 404', () => {
       sinon.stub(request, 'put').yields(null, { statusCode: 404 }, null);
       sinon.stub(request, 'post').yields(null, { statusCode: 204 }, null);
@@ -518,6 +551,14 @@ describe('Eureka client', () => {
       client.transformRegistry.restore();
     });
 
+    it('should should trigger registryUpdated event', () => {
+      sinon.stub(request, 'get').yields(null, { statusCode: 200 }, null);
+      const eventSpy = sinon.spy();
+      client.on('registryUpdated', eventSpy);
+      client.fetchRegistry();
+      expect(eventSpy).to.have.been.calledOnce;
+    });
+
     it('should call registry URI', () => {
       sinon.stub(request, 'get').yields(null, { statusCode: 200 }, null);
       const registryCb = sinon.spy();