Building Microservices using Hydra A hands-on workshop @cjus (twitter / github) https://goo.gl/GzJ1JP 

Prereqs • Your favorite text editor or: https://atom.io/ • Your favorite terminal app or: iTerm2 / Hyper.js • NodeJS: https://nodejs.org
 * Requires Node 6.2.1 or greater • Lastly, if you’re cruising along - help the person sitting next to you! 

Code examples at: https://goo.gl/AVW0lG 

Microservices • Microservice: a process which is dedicated to doing a kind of thing really well • A distributed computing application - works across a network • Commonly implemented using ExpressJS and other lesser known frameworks 

Monolithic vs Microservice 

Monolithic Microservice “mono” - meaning one “micro” - meaning small 

Monolithic • Pros: • easier to deploy • easier to test • Cons: • can become too large for anyone on the team to fully understand • can be fragile due to the fact that a single error can take down the entire system • can be difficult to modify as modules are tightly coupled • can be difficult to build using remote teams • often requires the same tech stack 

Microservice • Pros: • collection of loosely connected services • easier / safer to modify • can be easy to deploy • can be easy to test since you’re focused on a particular set of functionality • can be built using different tech stacks • Cons: • can be difficult to test due to its distributed nature • routing endpoints can require more consideration • services may need to discover one another 

Who builds microservices? • Amazon, Comcast, eBay, IBM, Google, Groupon, Microsoft, Netflix, Paypal, SoundCloud, Uber • … and lots of other companies 

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$ mkdir express-test $ cd express-test $ npm init { name app: index } $ npm install express ——save 

$ vi index.js var express = require('express') var app = express() app.get('/', function (req, res) { res.send('Hello World!') }) app.listen(3000, function () { console.log('Example app listening on port 3000!') }) Cut & paste from: express-hello.js https://goo.gl/AVW0lG 

$ node index.js View in web browser: http://localhost:3000/ 

What’s Hydra? • An NPM package that facilitates building distributed applications - such as microservices • It addresses distributed computing concerns so you won’t have to • Open Source project - released by Flywheel Sports • Related projects: hydra-express, hydra-router 

Hydra features • Automated health and presence • Automated service discovery • Inter-service (P2P) communication with support for socket messaging and RESTful interfaces • Built-in load balancing and routing • Self registration with near zero configuration • Built-in job queues • Built on Node using native ES6 • Great with Docker 

The hydra project consist of: hydra-core, hydra-express and hydra-router In this workshop we’ll focus on Hydra Express 

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Hydra has a single infrastructure dependency 

See our intro to Redis at: https://goo.gl/S11jdo 

Let’s upgrade our basic express app using hydra-express $ npm install fwsp-hydra-express ——save 

$ vi index.js var hydraExpress = require('fwsp-hydra-express'); var config = require('./config.json'); function onRegisterRoutes() { var express = hydraExpress.getExpress(); var api = express.Router(); api.get('/', function(req, res) { res.send('Hello World!'); }); hydraExpress.registerRoutes({ '': api }); } hydraExpress.init(config, onRegisterRoutes); Cut & paste hydra-express-hello.js from: https://goo.gl/AVW0lG 

$ vi config.json { "hydra": { "serviceName": "hello", "serviceIP": "", "servicePort": 3000, "serviceType": "", "serviceDescription": "", "redis": { "url": "172.16.0.2", "port": 6379, "db": 15 } } } Cut & paste config.json from: https://goo.gl/AVW0lG 

$ node index.js View in web browser: http://localhost:3000/ 

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$ sudo npm install -g hydra-cli $ hydra-cli config redisUrl: 172.16.0.2 redisPort: 6379 redisDb: 15 

$ hydra-cli hydra-cli version 0.3.5 Usage: hydra-cli command [parameters] See docs at: https://github.com/flywheelsports/hydra-cli A command line interface for Hydra services Commands: help - this help list config - configure connection to redis config list - display current configuration health [serviceName] - display service health healthlog serviceName - display service health log message create - create a message object message send message.json - send a message nodes [serviceName] - display service instance nodes rest path [payload.json] - make an HTTP RESTful call to a service routes [serviceName] - display service API routes services [serviceName] - display list of services 

$ hydra-cli nodes $ hydra-cli routes $ hydra-cli health hello 

$ hydra-cli rest hello:[get]/ 

$ vi config.json { "hydra": { "serviceName": "hello", "serviceIP": "", "servicePort": 0, "serviceType": "", "serviceDescription": "", "redis": { "url": "172.16.0.2", "port": 6379, "db": 15 } } } Cut & paste config.json from: https://goo.gl/AVW0lG Change from 3000 to 0 

$ vi index.js var hydraExpress = require('fwsp-hydra-express'); var hydra = hydraExpress.getHydra(); var config = require('./config.json'); function onRegisterRoutes() { var express = hydraExpress.getExpress(); var api = express.Router(); api.get('/', function(req, res) { res.send({ msg: `hello from ${hydra.getServiceName()} - ${hydra.getInstanceID()}` }); }); hydraExpress.registerRoutes({ '': api }); } hydraExpress.init(config, onRegisterRoutes); Cut & paste
 hydra-express-hello-id.js from: https://goo.gl/AVW0lG 

$ hydra-cli rest hello:[get]/ $ hydra-cli rest hello:[get]/ $ hydra-cli nodes 

$ hydra-cli rest hello:[get]/ $ hydra-cli rest hello:[get]/ $ hydra-cli rest hello:[get]/ { Load balanced! } 

$ hydra-cli nodes $ hydra-cli rest 45dc1730a9ec92fea6c9c0e0e7d52681@hello:[get]/ 

var hydraExpress = require('fwsp-hydra-express'); var config = require('./config.json'); function onRegisterRoutes() { var express = hydraExpress.getExpress(); var api = express.Router(); api.get('/', function(req, res) { res.send('Hello World!'); }); hydraExpress.registerRoutes({ '': api }); } hydraExpress.init(config, onRegisterRoutes); var express = require('express') var app = express() app.get('/', function (req, res) { res.send('Hello World!') }) app.listen(3000, function () { console.log('Example app listening on port 3000!') }) Side by side comparison 

Improved routes 

$ vi index.js var hydraExpress = require('fwsp-hydra-express'); var hydra = hydraExpress.getHydra(); var config = require('./config.json'); function onRegisterRoutes() { var express = hydraExpress.getExpress(); var api = express.Router(); api.get('/hello', function(req, res) { res.send({ msg: `hello from ${hydra.getServiceName()} - ${hydra.getInstanceID()}` }); }); hydraExpress.registerRoutes({ '/v1': api }); } hydraExpress.init(config, onRegisterRoutes); Cut & paste
 hydra-express-hello-route.js from: https://goo.gl/AVW0lG 

$ node index.js $ hydra-cli nodes $ hydra-cli rest hello:[get]/v1/hello 

Building more complex services 

$ sudo npm install -g yo generator-fwsp-hydra $ yo fwsp-hydra { name it “hello” } 

$ tree hello-service hello-service !"" README.md !"" config # !"" config.json # $"" sample-config.json !"" package.json !"" hello-service.js !"" routes # $"" hello-v1-routes.js !"" scripts # $"" docker.js $"" specs !"" helpers # $"" chai.js $"" test.js 5 directories, 9 files 

$ cd hello-service $ vi config/config.json { "appServiceName": "hello-service", "environment": "development", "hydra": { "serviceName": "hello-service", "serviceIP": "", "servicePort": 0, "serviceType": "hello", "serviceDescription": "", "redis": { "url": "127.0.0.1", "port": 6379, "db": 15 } } } 

$ vi config/config.json "redis": {
 "url": "127.0.0.1",
 "port": 6379,
 "db": 15
 } Update to 172.16.0.2 

// In routes/hello-v1-routes.js // … res.sendOk({ msg: `hello from ${hydra.getServiceName()} - ${hydra.getInstanceID()}` }); 

$ cd hello-service $ npm install $ node hello-service or $ npm start 

$ npm start > [email protected] start /Users/cjustiniano/dev/hello-service > node hello-service.js INFO { event: 'info', message: 'Successfully reconnected to redis server' } INFO { event: 'start', message: 'hello-service (v.0.0.1) server listening on port 13664' } INFO { event: 'info', message: 'Using environment: development' } serviceInfo { serviceName: 'hello-service', serviceIP: '172.16.0.12', servicePort: 13664 } 

$ hydra-cli nodes $ hydra-cli routes $ hydra-cli rest hello:[get]/v1/hello 

Inter-service Communication 

$ yo fwsp-hydra { Create a “blue” or “red” service } 

$ vi {red/blue}-service.js hydraExpress.init(config.getObject(), version, () => { hydraExpress.registerRoutes({ '/v1/red': require('./routes/red-v1-routes') }); }) .then((serviceInfo) => { console.log('serviceInfo', serviceInfo); let hydra = hydraExpress.getHydra(); let message = hydra.createUMFMessage({ to: 'blue-service:[get]/v1/blue/', from: 'red-service:/', body: {} }); hydra.makeAPIRequest(message) .then((response) => { console.log('response', response); }); return 0; }) Cut & paste
 red-blue-service.js from: https://goo.gl/AVW0lG Edit “red” or “blue” words accordingly 

INFO { event: 'info', message: 'Successfully reconnected to redis server' } INFO { event: 'start', message: 'red-service (v.0.0.1) server listening on port 13185' } INFO { event: 'info', message: 'Using environment: development' } serviceInfo { serviceName: 'red-service', serviceIP: '172.16.0.12', servicePort: 13185 } response { statusCode: 200, statusMessage: 'OK', statusDescription: 'Request succeeded without error', result: { msg: 'hello from blue-service - 088c270d30d36fdda37564de2cc68773' } } 

Recap 

ExpressJS apps are fairly easy to build 

Hydra-Express adds just a bit more code! 

And we get a great deal for that extra code 

We saw that even a basic hydraExpress app emits health and presence information 

We saw that our routes are discoverable 

And automatically load-balanced! 

Hydra-cli made it easy to communicate and test our services 

The hydra generator tool allowed us to quickly build microservice projects 

We saw inter-service communication using UMF messages and the hydra.makeAPIRequest 

Resources! • Hydra project: https://github.com/flywheelsports • Hydra Intro: https://goo.gl/Ikcx4q • Getting Redis: https://goo.gl/S11jdo • Code used in this workshop: https://goo.gl/AVW0lG