Docker-Rails
[]
(https://circleci.com/gh/ad2games/docker-rails)
An opinionated docker image for running Rails apps in production.
Uses Puma, Sidekiq, Clockwork and rails_migrate_mutex. Everything is optional.
Quick Example
- Create a new Rails app (
$ rails new my_blog
) - Create a
Dockerfile
in the app root with this content:FROM ad2games/docker-rails:latest
- Add
gem 'puma'
to theGemfile
and runbundle install
- Build the docker container:
$ docker build -t my_blog .
- Run the container:
$ docker run -p 8080:8080 -e RAILS_ENV=development my_blog
- Open
http://localhost:8080
- Enjoy!
This example is for demo purposes only. Docker-Rails is intended for production use, not local development. Please read the whole README before using.
Docker Image
The image is built by us, squashed into a single layer and pushed to Docker Hub.
To use it in your app, create a Dockerfile
with the following content:
FROM ad2games/docker-rails:<VERSION>
and replace <VERSION>
with the current version number.
Add more docker steps if needed (usually not), build and deploy to your infrastructure.
We use eb_deployer to deploy our apps to AWS Elastic Beanstalk.
Contents
Rails App Server / Puma
Puma is used as the web server for your app. For this to work properly, please add the following gems to your Gemfile:
gem 'puma'
gem 'rack-timeout', group: :production
gem 'rails_12factor', group: :production # only for Rails < 5
You can configure Puma:
Environment Variable | Description | Default Value |
---|---|---|
PUMA_WORKERS | Number of worker processes | [number of CPU cores] |
PUMA_MAX_THREADS | Maximum number of threads per process | 16 |
PUMA_MIN_THREADS | Minimum number of threads per process | PUMA_MAX_THREADS |
You can also create a config/puma.rb
file in your app that contains additional configuration.
Have a look at the Puma configuration file for more details.
Sidekiq
Sidekiq is used for processing background jobs. A sidekiq process
will be automatically started when the sidekiq
gem is present in your app. Using sidekiq is
optional.
You can configure sidekiq:
Environment Variable | Description | Default Value |
---|---|---|
SIDEKIQ_THREADS | Number of threads | 16 |
You can also create a config/sidekiq.yml
file in your app that contains additional configuration.
The default configuration enables the default
and mailers
queues.
Clockwork
Clockwork is used for scheduling background jobs.
A clockwork process will be automatically started when the clockwork
gem is present in your app.
Using clockwork is optional.
You need to create a config/clockwork.rb
file using the following schema:
module Clockwork
every(1.hour, 'my_job') { MyWorker.perform_async }
end
Note that the clockwork process is started in every container. We recommend using sidekiq-unique-jobs to ensure that jobs are scheduled only once.
Rails Migrations / rails_migrate_mutex
rails_migrate_mutex is used to run Rails migrations. If you have the gem installed in you app, migrations are automatically run on container startup. Using rails_migrate_mutex is optional.
Ruby / Packages
The latest ruby version is included in the container. It is compiled from source and uses jemalloc. The latest rubygems and bundler versions are installed as well.
The following tools are installed: git
, nodejs
, imagemagick
, curl
, bower
.
Development packages for compiling the following gems are included:
sqlite3
, pg
, mysql2
, nokogiri
.
Have a look at the Base Dockerfile for more details.
App Installation / Docker ONBUILD
The final docker image has ONBUILD hooks that set up your application.
It installs all gems except those in the development
and test
groups.
If the sprockets
gem is present (default for Rails apps), it also precompiles assets. If you need any environment
variables set for compiling assets, you can specify them in a .env
file in your app root. This
file will be sourced before running the task. Newer versions of sprockets will also automatically
created gzipped versions of the assets. Rails then uses these static gzip files to serve assets.
Have a look at the ONBUILD Dockerfile for more details.
Environment Variables
All environment variables are passed on the application. Both RAILS_ENV
and RACK_ENV
are
set to production
and should not be changed.
Both RAILS_SERVE_STATIC_FILES
and
RAILS_LOG_TO_STDOUT
are set, so you
don't need to
include the rails_12factor
gem anymore if you're using Rails 5 or above and have updated
your config/environments/production.rb
file.
License
MIT, see LICENSE.txt
Contributing
Please create a new GitHub Issue if you encounter a bug or have a feature request.
Feel free to fork and submit pull requests!