A JavaScript implementation of a client for Eureka (https://github.com/Netflix/eureka), the Netflix OSS service registry.

First, install the module into your node project:

npm install eureka-js-client --save

The Eureka module exports a JavaScript function that can be constructed.

var Eureka = require('eureka-js-client').Eureka;

// example configuration
var client = new Eureka({
  // application instance information
  instance: {
    app: 'jqservice',
    hostName: 'localhost',
    ipAddr: '127.0.0.1',
    port: 8080,
    vipAddress: 'jq.test.something.com',
    dataCenterInfo: {
      name: 'MyOwn'
    }
  },
  eureka: {
    // eureka server host / port
    host: '192.168.99.100',
    port: 32768
  }
});

The Eureka client searches for the YAML file eureka-client.yml in the current working directory. It further searches for environment specific overrides in the environment specific YAML files (e.g. eureka-client-test.yml). The environment is typically development or production, and is determined by the NODE_ENV environment variable. The options passed to the constructor overwrite any values that are set in configuration files.

You can configure a custom directory to load the configuration files from by specifying a cwd option in the object passed to the Eureka constructor.

var client = new Eureka({
  cwd: __dirname + '/config'
});

If you wish, you can also overwrite the name of the file that is loaded with the filename property. However, this disables the environment-based configuration loaded. You can mix the cwd and filename options.

var client = new Eureka({
  filename: 'eureka.yml',
  cwd: __dirname + '/config'
});

client.start();

client.stop();

// appInfo.application.instance contains array of instances
var appInfo = client.getInstancesByAppId('YOURSERVICE');

// appInfo.application.instance contains array of instances
var appInfo = client.getInstancesByVipAddress('YOURSERVICEVIP');

For AWS environments (dataCenterInfo.name == 'Amazon') the client has built-in logic to request the AWS metadata that the Eureka server requires. See Eureka REST schema for more information.

// example configuration for AWS
var client = new Eureka({
  // application instance information
  instance: {
    app: 'jqservice',
    port: 8080,
    vipAddress: 'jq.test.something.com',
    statusPageUrl: 'http://__HOST__:8080/',
    healthCheckUrl: 'http://__HOST__:8077/healthcheck',
    dataCenterInfo: {
      name: 'Amazon'
    }
  },
  eureka: {
    // eureka server host / port / EC2 region
    host: 'eureka.test.mydomain.com',
    port: 80
  }
});

Notes:

• Under this configuration, the instance hostName and ipAddr will be set to the public host and public IP that the AWS metadata provides.
• For status and healthcheck URLs, you may use the replacement key of __HOST__ to use the public host.
• Metadata fetching can be disabled by setting config.eureka.fetchMetadata to false if you want to provide your own metadata in AWS environments.

If your have multiple availability zones and your DNS entries set up according to the Wiki article Configuring Eureka in AWS Cloud, you'll want to set config.eureka.useDns to true and set config.eureka.ec2Region to the current region (usually this can be pulled into your application via an environment variable, or passed in directly at startup).

This will cause the client to perform a DNS lookup using config.eureka.host and config.eureka.ec2Region. The naming convention for the DNS TXT records required for this to function is also described in the Wiki article above.

The library uses 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.

NODE_DEBUG=request node example.js

You can also turn on debugging within the library by setting the log level to debug:

client.logger.level('debug');

The test for the module are written using mocha and chai. To run the unit tests, you can use the gulp test task:

gulp test

If you wish to have the tests watch the src/ and test/ directories for changes, you can use the test:watch gulp task:

gulp test:watch