Docker on Rails

Setup docker

To create a new ruby on rails project you don't need to install any software instead of Docker and Docker Compose. For Mac or Windows I recommend Docker Toolbox.

Docker Toolbox

After installing the Docker Toolbox you need to create a new Docker Machine. In this case the machine name is dev and the disk size is 20GB. You can change it if you want.

docker-machine create --virtualbox-disk-size 20000 --driver virtualbox dev

I prefer to install docker-machine-nfs as well.

curl -s https://raw.githubusercontent.com/adlogix/docker-machine-nfs/master/docker-machine-nfs.sh |
  sudo tee /usr/local/bin/docker-machine-nfs > /dev/null && \
  sudo chmod +x /usr/local/bin/docker-machine-nfs

After installing docker-machine-nfs we can use nfs instead of shared folders. This is much faster.

docker-machine-nfs dev

Enable docker to use the created machine.

eval "$(docker-machine env dev)"

Open /etc/exports and replace -mapall=$uid:$gid with -maproot=0 and restart the service sudo nfsd restart.

One last step is to set the IP from the docker machine to your /etc/hosts file. Replace rails.dev.io to a domain how you want to reach the project locally.

echo "192.168.99.100 rails.dev.io" | sudo tee -a /etc/hosts

That's all for setting up our environment.

SSL

If you run you application you need to generate a SSL certificate and store it in docker/nginx/ssl. Then change the parameters ssl_certificate and ssl_certificate_kes in docker/nginx/sites-enabled/rails.conf.

Starting with Docker on Rails

Create a new project

At first you need to clone this repository and go to the repository folder.

git clone git@github.com:mc388/docker-on-rails.git && cd docker-on-rails

Next you can create a new ruby on rails project. In this case we create a rails project in version 5.0.0.beta1 (you can change the version in the Dockerfile). Let's create a new project.

docker-compose run --rm rails rails new . -d mysql -T

The installer will ask you if you want to overwrite the README.md file. It is your choice if you want to keep this file or replace it with the README.md from rails.

And that's it. The new project is created.

Because docker is running as root you may need to change the owner of the generated files.

sudo chown -R $USER .

Setup database connection

The next step is to setup the database connection in config/database.yml. This is the default configuration. I only changed the host to mysql and the database to rails_dev. The host mysql is the name of the docker container. The database name is set in the docker-compose.yml. Feel free to change the name.

default: &default
  adapter: mysql2
  encoding: utf8
  pool: 5
  username: root
  password:
  host: mysql

development:
  <<: *default
  database: rails_dev

Start the webserver

After creating the project we can test if everything if working.

docker-compose up -d

If you now visit the url you set in you /etc/hosts file you should see the default ruby on rails page.

Run commands

You can easily run all rails, rake or bundle commands inside the rails docker container. Replace <my command> with something like bundle install or rails g scaffold user name:string

docker-compose run --rm rails <my command>