adding AWS metadata client, and related tests

src/aws-metadata.js

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+import request from 'request';
+import async from 'async';
+import {Logger} from './Logger';
+
+/*
+  Utility class for pulling AWS metadata that Eureka requires when registering as an Amazon instance (datacenter).
+*/
+export class AwsMetadata {
+
+  constructor(config = {}) {
+    this.logger = config.logger || new Logger();
+    this.host = config.host || '169.254.169.254';
+  }
+
+  fetchMetadata(resultsCallback) {
+    async.parallel({
+      'ami-id': callback => {
+        this.lookupMetadataKey('ami-id', callback);
+      },
+      'instance-id': callback => {
+        this.lookupMetadataKey('instance-id', callback);
+      },
+      'instance-type': callback => {
+        this.lookupMetadataKey('instance-type', callback);
+      },
+      'local-ipv4': callback => {
+        this.lookupMetadataKey('local-ipv4', callback);
+      },
+      'local-hostname': callback => {
+        this.lookupMetadataKey('local-hostname', callback);
+      },
+      'availability-zone': callback => {
+        this.lookupMetadataKey('placement/availability-zone', callback);
+      },
+      'public-hostname': callback => {
+        this.lookupMetadataKey('public-hostname', callback);
+      },
+      'public-ipv4': callback => {
+        this.lookupMetadataKey('public-ipv4', callback);
+      },
+      mac: callback => {
+        this.lookupMetadataKey('mac', callback);
+      },
+      accountId: callback => {
+        // the accountId is in the identity document.
+        this.lookupInstanceIdentity((error, identity) => {
+          callback(null, identity ? identity.accountId : null);
+        });
+      }
+    }, (error, results) => {
+      // we need the mac before we can lookup the vpcId...
+      this.lookupMetadataKey('network/interfaces/macs/' + results.mac + '/vpc-id', (error, vpcId) => {
+        results['vpc-id'] = vpcId;
+        this.logger.info('Instance AWS Metadata', results);
+        resultsCallback(results);
+      });
+    });
+  }
+
+  lookupMetadataKey(key, callback) {
+    request.get({
+      url: `http://${this.host}/latest/meta-data/${key}`
+    }, (error, response, body) => {
+      if (error) {
+        this.logger.error('Error requesting metadata key', error);
+      }
+      callback(null, (error || response.statusCode !== 200) ? null : body);
+    });
+  }
+
+  lookupInstanceIdentity(callback) {
+    request.get({
+      url: `http://${this.host}/latest/dynamic/instance-identity/document`
+    }, (error, response, body) => {
+      if (error) {
+        this.logger.error('Error requesting instance identity document', error);
+      }
+      callback(null, (error || response.statusCode !== 200) ? null : JSON.parse(body));
+    });
+  }
+}

test/aws-metadata.test.js

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+import sinon from 'sinon';
+import chai from 'chai';
+import sinonChai from 'sinon-chai';
+import request from 'request';
+import {AwsMetadata} from '../src/aws-metadata';
+
+let expect = chai.expect;
+chai.use(sinonChai);
+
+describe('AWS Metadata client', () => {
+
+  describe('fetchMetadata()', () => {
+
+    let client;
+    beforeEach(() => {
+      client = new AwsMetadata({host: '127.0.0.1:8888'});
+    });
+
+    afterEach(() => {
+      request.get.restore();
+    });
+
+    it('should call metadata URIs', () => {
+
+      let requestStub = sinon.stub(request, 'get');
+
+      requestStub.withArgs({
+        url:'http://127.0.0.1:8888/latest/meta-data/ami-id'
+      }).yields(null, {statusCode: 200}, 'ami-123');
+
+      requestStub.withArgs({
+        url:'http://127.0.0.1:8888/latest/meta-data/instance-id'
+      }).yields(null, {statusCode: 200}, 'i123');
+
+      requestStub.withArgs({
+        url:'http://127.0.0.1:8888/latest/meta-data/instance-type'
+      }).yields(null, {statusCode: 200}, 'medium');
+
+      requestStub.withArgs({
+        url:'http://127.0.0.1:8888/latest/meta-data/local-ipv4'
+      }).yields(null, {statusCode: 200}, '1.1.1.1');
+
+      requestStub.withArgs({
+        url:'http://127.0.0.1:8888/latest/meta-data/local-hostname'
+      }).yields(null, {statusCode: 200}, 'ip-127-0-0-1');
+
+      requestStub.withArgs({
+        url:'http://127.0.0.1:8888/latest/meta-data/placement/availability-zone'
+      }).yields(null, {statusCode: 200}, 'fake-1');
+
+      requestStub.withArgs({
+        url:'http://127.0.0.1:8888/latest/meta-data/public-hostname'
+      }).yields(null, {statusCode: 200}, 'ec2-127-0-0-1');
+
+      requestStub.withArgs({
+        url:'http://127.0.0.1:8888/latest/meta-data/public-ipv4'
+      }).yields(null, {statusCode: 200}, '2.2.2.2');
+
+      requestStub.withArgs({
+        url:'http://127.0.0.1:8888/latest/meta-data/mac'
+      }).yields(null, {statusCode: 200}, 'AB:CD:EF:GH:IJ');
+
+      requestStub.withArgs({
+        url:'http://127.0.0.1:8888/latest/dynamic/instance-identity/document'
+      }).yields(null, {statusCode: 200}, '{"accountId":"123456"}');
+
+      requestStub.withArgs({
+        url:'http://127.0.0.1:8888/latest/meta-data/network/interfaces/macs/AB:CD:EF:GH:IJ/vpc-id'
+      }).yields(null, {statusCode: 200}, 'vpc123');
+
+      let fetchCb = sinon.spy();
+      client.fetchMetadata(fetchCb);
+
+      expect(request.get).to.have.been.callCount(11);
+
+      expect(fetchCb).to.have.been.calledWithMatch({
+        'accountId': '123456',
+        'ami-id': 'ami-123',
+        'availability-zone': 'fake-1',
+        'instance-id': 'i123',
+        'instance-type': 'medium',
+        'local-hostname': 'ip-127-0-0-1',
+        'local-ipv4': '1.1.1.1',
+        'mac': 'AB:CD:EF:GH:IJ',
+        'public-hostname': 'ec2-127-0-0-1',
+        'public-ipv4': '2.2.2.2',
+        'vpc-id': 'vpc123'
+      });
+
+    });
+
+  });
+
+});