Docker: What It Is and Why You Should Care

A brief explanation of what Docker actually is and instructions for setting up a Rails dev environment in Docker.

Transcript

1. Docker What It Is and Why You Should Care
2. My Story
3. What is Docker? Virtualization
6. = Virtual Machines Guest Host
7. = Docker Containers
8. That’s all great. Why should I care?
9. • Install Homebrew • brew install several packages - SQL, Imagemagick • Install RVM or Rbenv • Install one or more versions of Ruby • Clone one or more Git repos • Run bundle/npm/bower/etc install for each repo
10. • Start the db server (unless it’s always running) • Start the rails app • Background workers? Sidekiq and Redis • SoA? Need to start those up too on the right port • iTerm or Tmux setup to run all this? Foreman? • Foreman requires same directory. Subcontractor.
12. • Install Docker • Clone your Git repos • Place your docker-compose.yml file
13. • docker-compose up
14. = Dev Dev
15. = Dev CI
16. ≈ Dev Prod
17. Where do I start?
18. Background: Building Blocks
19. Background Tools
20. • Dockerfile • docker-compose.yml
21. Docker Engine - Dockerfile
22. FROM ruby:2.3.1-slim RUN apt-get update -qq && apt-get install -y \ build-essential libpq-dev postgresql-client ENV RAILS_ROOT /var/www/myapp RUN mkdir -p $RAILS_ROOT/tmp/pids WORKDIR $RAILS_ROOT COPY Gemfile Gemfile COPY Gemfile.lock Gemfile.lock RUN gem install bundler RUN bundle install
23. Docker Compose YAML
24. app: build: . command: rails server --port 3000 --binding 0.0.0.0 environment: RAILS_ENV: development DATABASE_HOST: db links: - db ports: - 3000:3000 volumes: - .:/var/www/myapp db: image: postgres:9.5.3 environment: POSTGRES_USER: username POSTGRES_PASSWORD: password volumes: - myapp-db:/var/lib/postgresql/data
25. sidekiq: build: . command: bundle exec sidekiq environment: REDIS_URL: redis://redis:6379 links: - db - redis volumes: - .:/var/www/myapp redis: image: redis
26. Dockerfile docker-compose.yml
27. Other Ways To Get Started
29. Takeaways • Docker reduces dev dependencies • It adds parity where it is used (Dev-CI-Production) • Easy to get started
30. Questions?
31. • Alexander Clark • Twitter @atheclark • Blog http://alexander-clark.com/blog • Github alexander-clark • Slack alexander-clark
32. Thanks for listening.