Ruby on Rails

Requirements:

• Rails 5.2.1 (latest)
• ruby 2.5.3
• postgresql
• reactjs
• imagemagick

Setup Ruby on Rails

1. Create new project

   rails new project_name -d postgresql --webpack=react
   

2. Setup database

   rails db:setup
   rails db:migrate
   

3. Create index_controller.rb to make sure Rails is running on localhost

4. Start server and visit http://localhost:3000

   rails server
   

Setup Docker

The docker setup is modified from the docker-rails repo.

Features:

• Use Alpine (ruby:2.5.3-alpine) as base image - smaller image size

• Use Multi-stage build - The idea is to first build the stuff and then copy only the resulting artefacts into the final image.

• Remove bundler cache - the cache folder, C source file and compiled object file for gems with native extensions.

  RUN rm -rf /usr/local/bundle/cache/*.gem \
    && find /usr/local/bundle/gems/ -name "*.c" -delete \
    && find /usr/local/bundle/gems/ -name "*.o" -delete
  

• Remove parts of the app not needed in resulting image - node_modules/, tmp/cache, spec/, test/ and the assets/ folders

  # Remove folders not needed in resulting image
  RUN rm -rf node_modules tmp/cache app/assets vendor/assets lib/assets spec
  

5. Add Dockerfile

6. Build the docker image

   docker build . -t terraform-rails
   

   ...
   ...
   Successfully built 04e42927d47b
   Successfully tagged terraform-rails:latest
   

7. Check that the image is built

   docker images
   

   REPOSITORY          TAG       IMAGE ID        CREATED                SIZE
   terraform-rails     latest    04e42927d47b    About a minute ago     203MB
   

Docker Compose

Compose is a tool for defining and running multi-container Docker applications.

Having dockerized your rails app is not enough, the app still needs to communite with other services, at the minimal, to a database server. Rails app contain is only one of the services.

By using Compose, you can define multiple container services and how they are linked to each other.

8. Add docker-compose.yml

9. Build containers

   docker-compose build
   

10. Check if the image is built

    docker images
    

    REPOSITORY          TAG        IMAGE ID         CREATED             SIZE
    terraform-rails     latest     724c9b8a43e8     32 seconds ago      203MB
    

11. Remember to change the database config

    # docker-compose.yml
    services:
      db:
        environment:
          - POSTGRES_PASSWORD
      ...
    
      app: &app_base
        ...
        ...
        environment:
          - POSTGRES_HOST=db
          - POSTGRES_PASSWORD
          - POSTGRES_USER=postgres
    

    # config/database.yml
    
    default: &default
      ...
      host: <%= ENV['POSTGRES_HOST'] %>
      username: <%= ENV['POSTGRES_USER'] %>
      password: <%= ENV['POSTGRES_PASSWORD'] %>
      ...
    
    

12. Start the containers

    docker-compose up
    

    To stop the containers

    docker-compose down
    

Nginx as web server

There are many reasons to use nginx as web server between your app and the users.

• Static redirects - you could setup your nginx to redirect all http traffic to the same url with https. This way such trivial requests will never hit your app server.
• Multipart upload - Nginx is better suited to handle multipart uploads. Nginx will combine all the requests and send it as a single file to puma.
• Serving static assets - It is recommended to serve static assets (those in /public/ endpoint in rails) via a webserver without loading your app server.
• There are some basic DDoS protections built-in in nginx.

13. Add devops/docker/web/Dockerfile for nginx container

14. Add devops/docker/web/nginx.conf

15. Configure docker-compose.yml to use nginx

    # docker-compose.yml
    ...
    ...
      web:
        build:
          context: .
          dockerfile: ./devops/docker/web/Dockerfile
        depends_on:
          - app
        ports:
          - 8080:80
    ...
    ...
    

16. Start the containers again

    docker-compose up
    

    Inspect your running containers, you should see 3 containers are running, only the web container are exposing the port 8080

    docker ps
    
    CONTAINER ID        IMAGE                 COMMAND                  CREATED             STATUS              PORTS                  NAMES
    8cccc470542f        terraform-rails_web   "nginx -g 'daemon of…"   2 minutes ago       Up 2 minutes        0.0.0.0:8080->80/tcp   terraform-rails_web_1
    382b29806b87        terraform-rails       "./devops/docker/sta…"   2 minutes ago       Up 2 minutes        3000/tcp               terraform-rails_app_1
    9b7077ef437b        postgres:alpine       "docker-entrypoint.s…"   2 minutes ago       Up 2 minutes        5432/tcp               terraform-rails_db_1
    

    Visit http://localhost:8080 for your app.

docker-sync

http://docker-sync.io

Developing with docker under OSX/ Windows is a huge pain, since sharing your code into containers will slow down the code-execution about 60 times.

17. Install docker-sync

    See installation guide

18. Configure docker-sync with docker-sync.yml

    # docker-sync.yml
    
    version: "2"
    
    options:
      verbose: true
    syncs:
      app-sync: # tip: add -sync and you keep consistent names as a convention
        src: './'
    
        # optional, default: docker-compose-dev.yml if you like, you can set a custom location (path) of your compose file.
        # Do not set it, if you do not want to use it at all
        #
        # if its there, it gets used, if you name it explicitly, it HAS to exist
        # HINT: you can also use this as an array to define several compose files to include. Order is important!
        compose-dev-file-path: 'docker-compose-sync.yml'
    
        # use 'native_osx' or 'unison'
        sync_strategy: 'unison'
    
        sync_excludes: ['.gitignore', '.git/', '.DS_Store']
    
        # this does not user groupmap but rather configures the server to map
        # optional: usually if you map users you want to set the user id of your application container here
        sync_userid: '1000'
    
        # optional, a list of regular expressions to exclude from the fswatch - see fswatch docs for details
        # IMPORTANT: this is not supported by native_osx
        watch_excludes: ['.*/.git', '.*/node_modules', '.*/bower_components', 'tmp', '.*/sass-cache', '.*/.sass-cache', '.*/.sass-cache', '.coffee', '.scss', '.sass', '.gitignore']
    
        # optional: use this to switch to fswatch verbose mode
        watch_args: '-v'
    

    See docker-sync configuration

19. Modify docker-compose.yml or use docker-compose-sync.yml which docker-sync will use to override the docker-compose.yml

    # docker-compose-sync.yml
    version: '3.4'
    
    services:
      app:
        volumes:
          - terraform-rails-app-sync:/app:nocopy
      worker:
        volumes:
          - terraform-rails-app-sync:/app:nocopy
    
    volumes:
      terraform-rails-app-sync:
        external: true
    

    WARNING: Because unison is a two-way sync, do not use the same volume name as your other apps, your codes might get replaced with your other apps.

20. Use docker-sync commands to replace docker-compose to start, stop and cleanup

    To start

    docker-sync-stack start
    

    To stop, just Ctrl-C

    To clean up,

    docker-sync-stack clean
    

Worker container (sidekiq and redis)

21. Install redis gem and use redis image

    # Gemfile
    
    gem 'redis', '~> 4.0'
    

    redis can also be used for ActionCable

    # docker-compose.yml
    ...
    
    redis:
      image: redis:5.0-alpine
      volumes:
        - redis_data:/data
    

22. Install sidekiq gem and configure it

    # Gemfile
    
    gem 'redis', '~> 4.0'
    

    # config/sidekiq.yml
    :concurrency: 5
    :pidfile: ./tmp/pids/sidekiq.pid
    :logfile: ./log/sidekiq.log
    :queues:
      - [default, 1]
      - [mailers, 2]
    

    # config/initializers/sidekiq.yml
    require 'sidekiq/api'
    
    redis_config = { url: ENV['REDIS_SIDEKIQ_URL'] }
    
    Sidekiq.configure_server do |config|
      config.redis = redis_config
    end
    
    Sidekiq.configure_client do |config|
      config.redis = redis_config
    end
    

23. Add a worker container to the docker-compose.yml and docker-compose-dev.yml

    # docker-compose.yml
    worker:
      <<: *app_base
      volumes:
        - .:/app
      command: bundle exec sidekiq
      ports: []
      depends_on:
        - app
        - redis
    

    # docker-sync.yml
    
    worker:
      volumes:
        - terraform-rails-app-sync:/app:nocopy
    

24. Start your containers

    docker-sync-stack start
    

    Inspect your containers

    $ docker ps
    
    CONTAINER ID        IMAGE                        COMMAND                  CREATED             STATUS              PORTS                       NAMES
    90e32b9e3842        terraform-rails              "bundle exec sidekiq"    17 minutes ago      Up 17 minutes       3000/tcp                    terraform-rails_worker_1
    c3d557215b8c        terraform-rails_web          "nginx -g 'daemon of…"   17 minutes ago      Up 17 minutes       0.0.0.0:8080->80/tcp        terraform-rails_web_1
    b52b96a11ee3        terraform-rails              "./devops/docker/sta…"   17 minutes ago      Up 17 minutes       3000/tcp                    terraform-rails_app_1
    f85601685371        postgres:alpine              "docker-entrypoint.s…"   17 minutes ago      Up 17 minutes       5432/tcp                    terraform-rails_db_1
    3ca3a2e387e3        redis:5.0-alpine             "docker-entrypoint.s…"   17 minutes ago      Up 17 minutes       6379/tcp                    terraform-rails_redis_1
    4f6028ab1d46        eugenmayer/unison:2.51.2.1   "/entrypoint.sh supe…"   17 minutes ago      Up 17 minutes       127.0.0.1:32797->5000/tcp   terraform-rails-app-sync
    

25. Configure ActiveJob to use sidekiq

    # config/application.rb
    
    config.active_job.queue_adapter = :sidekiq
    

Docker for production

Docker image for production requires different docker-compose configuration.

26. Add docker-compose-prod.yml

The differences between development and production:-

• restart: always
• healthcheck
• hostname
• cleaner and leaner - without development:test bundle, remove unnecessary folders, no EXECJS_RUNTIME
• no volumes: .:/app for production
• IMPORTANT: need to mount the config/master.key as volume for production enviroment

27. To run production environment on localhost

    # start docker-compose for production
    docker-compose -f docker-compose-prod.yml up
    

Terraform

Even with docker for production, you will still need to setup the infrastructure that support docker containers (and other services).

Terraform is a infrastructure-as-a-code tool to declare your infrastructure with easy to read and write DSL. A tool to provision and deploy infrastructure. (See Terraform for more information)

See Also

• Tips
• Troubleshooting
• Ruby on Rails
• docker
• aws
• terraform