Example of a Rails App with Docker Compose for development

This is an example of how I use Docker and Docker Compose to develop my rails apps.

It is an ideal project setup for new and experienced developers alike, and allows to a nearly trouble-free environment setup in their development machines.

In this example we'll fire up a full app environment consisting of the following:

• A postgres container which hosts the app's database.
• A redis container which hosts the app's job queue.
• An example Rails app running 3 processes on separate containers:
  • A web container running the Rails web server.
  • A worker container running the app's job processor (Sidekiq).
  • A test container running guard, which fires tests automatically whenever the app code changes. We'll also use this container to launch remote debugging sessions to the running web and worker containers.

You'll need to follow some instructions to get this example running:

1: Requirements

You must have both Docker (or a Docker Machine host) and Docker Compose running on your machine.

You can find instructions for the recommended setup on Linux, Mac OSX and Windows 8+.

2: Cloning the project

You should clone the project into a conveniently-named directory, as this repo's name is big enough to make typing docker/compose commands tiresome, should the need arise:

git clone https://github.com/vovimayhem/docker-compose-rails-dev-example.git example

3: Initialize the app environment in an initial run:

The setup-development-with-docker.sh script will do the following:

1. Generate an .env file, into which we'll store sensitive info (passwords, SECRET_KEY_BASE, etc). This file shouldn't be in version control
2. Generate the app's config/secrets.yml file, which will read the SECRET_KEY_BASE environment variable for all rails app environments.
3. Run the bundler command to install the app dependencies in the app's vendor/bundle folder.
4. Run the 'rake db:setup' command to initialize the database.

cd example && ./setup-development-with-docker.sh

Edit if you need the generated .env file.

4: Bring online the project's containers

docker-compose up -d

That's it! Check the running app web interface: http://localhost:3000

5: Next steps

I usually do some tricks to aid in my day to day activities:

• Modify the /etc/hosts file for rails apps that depend on subdomains.
• Generate aliases to the docker-compose command, as the docker-compose command tires my delicate fingers...
• Mess around with the compose commands to start & stop the project's containers.
• VERY IMPORTANT Launch a remote debug session easily to any of the project's app containers, as Docker makes debugging with byebug not so trivial.
• Running rails/rake commands on one-off containers, which is necessary quite often.
• Create a new rails app using docker, if you find yourself in the need of creating a new app, and you are already running this example project.

6: Example app ruby version

It uses MRI ruby 2.2.2. I'll make some branches using different engines (i.e. Rubinius, JRuby)

7: More Information

• Everything Docker
• GIANT ROBOTS SMASHING INTO OTHER GIANT ROBOTS (Seriously, thoughtbot?)
• Introducing 'heroku docker:release': Build & Deploy Heroku Apps with Docker geez! These guys are on EVERYTHING!

8: Contributing

I'd love to receive feedback & suggestions from everyone. If you see something off, or think there's a better way to do something this thing does, please do:

• Fork the original repository.
• Make your changes in a topic branch.
• Send a pull request.

License

This is free software, and may be redistributed under the terms specified in the LICENSE file.