Ruby On Rails On Docker

This is a little project of mine where I try to set up a Ruby on Rails production environment running on Docker. It is work in progress. Every step to get the application running should be provided here.

Notice: These steps are not considered "best practice". They're just the steps which got it working. I'm sure there is much room for improvement.

Todo:

• MySQL container
• Rails container using Unicorn
• Nginx as load balancer/reverse proxy
• Memcached for caching
• Sidekiq container for background jobs
• Use Brightbox Ruby Packages instead of RVM
• Using Docker Compose for orchestration
• Use data volume containers for Mysql data
• Fluentd for log collection
• Elasticsearch for log storage
• Kibana for log analysis
• MySQL Slave for backups
• Replace MySQL with Postgres

Environment: I am running this on a Mac using the boot2docker command line tool.

Boot2docker exposes all its ports on its IP address. This address is usually 192.168.59.103. It tells you its IP when you run boot2docker ip. To make reaching the vm more comfortable and to use the virtual host feature I made an entry in my /etc/hosts:

192.168.59.103   beer.docker

All services within the boot2docker VM are now reachable via beer.docker: from my OS X command line.

Quick Start

First install boot2docker and the Docker command line tools. How this is done is very well documented all over the internet. Then start that whole stuff:

boot2docker up
$(boot2docker shellinit)
docker-compose run web bundle exec rake db:setup
docker-compose up

All containers should now be running and you should be able to navigate your browser to the page http://beer.docker.

How it works

All containers are managed by docker-compose. You can see the configuration in the docker-compose.yml file.

The nginx proxy container contains the docker-gen service. This listens for new and stopped containers. As soon as a container with a VIRTUAL_HOST environment variable starts, it re-creates the nginx config file and reloads nginx.

Scaling up the app is as easy as running docker-compose scale web=4. Now you have 4 running web containers. The nginx proxy service acts as a load balancer in front of them.