@__omar__

• Backend lead at Playlab Games (for another week)
• Python, ruby, javascript
• Working with ruby and rails at Playlab, with a little nodejs on the side

Scope of this talk

• What are microservices?
• Do you want them?
• How do you do it?
• Microservices at Playlab
• Lessons learned

What are microservices?

Service-Oriented Architecture (SOA)?

What I'm going to talk about:

• Taking a big monolithic web application and splitting it up into little pieces, or microservices.
• Each microservice runs as a separate process
• Services communicate over the network (http)

Microservices at Playlab

• Currently migrating to microservices on the backend
  • Data persistence
  • User authentication
  • In-app purchase verification
  • Leaderboards
  • Events collector for analytics
• Mostly rails, some nodejs
• Work in progress!

Why would I want to do this?

Why would I want to do this?

• Separation of concerns
• Contain failures
• Scale services independently
• Use the right tool for each job
• Amazon, Netflix

Why would I not want to do this?

• Increased ops workload
• These goals can all be achieved in a monolithic codebase, if you have the discipline
• Etsy, Facebook

Rule of thumb

def is_this_a_good_idea?
  if ops_wizard? or using_heroku?
    'go for it'
  else
    'probably not'
  end
end

Where to start

• Identify the main things your application does
• Try to keep services as separate as possible (best if they don't have to talk to each other)
• Start with something easy
• Settle on some common identifiers: user ids, etc.

Checklist

• Good test coverage
• Automated deploys
• Monitoring
• Documentation

Examples

Events collector

• Analytics backend
• Nodejs
• Just one endpoint: POST /events
• Takes arbitrary json data
• Compresses it, chunks it and stores it on S3

DataCubes

• Data persistence service
• Rails
• Simple api
  • GET /users/:id/:game
  • PUT /users/:id/:game
• Calls our passport service to check user's auth token
• Revision tracking, conflict detection
• Currently uses mysql, we are considering more scalable alternatives

Passport

• Auth/identity service
• Rails
• Two endpoints
  • POST /:game/login
  • GET /:game/verify/:id
• Stores user data in postgres
• Auth tokens stored in redis

Scrooge

• Payment verification service
• Nodejs
• Synchronous api
  • POST /amazon
  • POST /apple
  • POST /google
• Stores payment data in postgres

TipTop

• Leaderboard service
• Rails
• Allows games to rank anything they like
• Uses redis sorted sets

Still to come

• Facebook activity feeds
• Admin panel
• ...

Operations

• Everything is containerized
• Deploy to CoreOS cluster hosted on AWS
• etcd for configuration
• Working on tooling to make it easier to deploy new services
• In the meantime we still prototype new services on heroku
• Continuous integration, automated deploys
• New Relic for performance monitoring - now with metrics for docker
• Sentry for error tracking

Lessons learned

• Still early days
• Looking good so far
  • Code is much nicer
  • New features are easier to implement

Code quality

• Great opportunity to refactor/rewrite
• Lint all new code, heavily
  • rubocop
  • reek
  • pronto
• Small codebases are easier to understand and maintain

DevOps

• Automate everything
• Make it easy to roll back changes
• Use heroku or other PaaS if you can
• Containerize
• Monitoring is essential

Backward compatibility

• Version your apis
• Much easier if your services don't need to talk to each other
• If they do, make sure you have integration tests

Dealing with the monolith

• Modify the monolith to call the new microservices
• Modify the new services to call the monolith
• Hack your way through: access the same data stores
• Much easier if you don't have to deal with this at all

Development

Use docker and fig (AKA docker-compose)

app:
  build: .
  volumes:
    - '.:/usr/src/app'
  environment:
    RAILS_ENV: development
  links:
    - database
    - redis
  ports:
    - '3000:3000'

database:
  image: postgres

redis:
  image: redis

Development

• Have a template for new services
  • https://github.com/pocket-playlab/rails-template
  • Dockerfile
  • docker-compose.yml
    • postgres
    • redis
  • Stripped-down rails base
  • rubocop and reek configuration
  • New Relic configuration
  • Sentry configuration
• Split reusable components into gems

tl;dr

• Build things fast, without worrying about old code
• Use the right tools for each service
• Be prepared to do more ops

Questions?

We're hiring

• DevOps
• Rails devs