Beluga is a tool for generating base docker images capable of running your Rails application. Since all Ruby applications require Ruby, and the gems in their Gemfile.lock, essentially the way the base image share similarities.

It currently assumes a Rails application, with a package.json file.

It uses the MIT-LICENSE.

1. Clone the repo

2. Build gem and install locally

$ rake install:local

Add new commands and configure images using config/beluga.yml. If you provide configuration for existing commands/images, the settings will be merged with beluga's config/default.yml.

images:
  <image-name>:
    tag: -- Docker Label. %s is the digest
    id_rsa: -- Where to find your id_rsa file. Defaults to ~/.ssh/id_rsa>
    from: -- From image name. Example 'devbase'
    extra_build_instructions: -- Extra Dockerfile instructions that are added to end
commands:
  <command-name>:
    command: -- Command to run. %s is a replacement for all the arguments.
    image: -- Name of docker image to run command in
    extra_hosts:
      - -- Extra hosts. For example: "db:<%= host_public_ip %>"

The configuration file is ERB aware, and has the following extra functions:

• host_public_ip: Returns the first public IP of the host

By default, beluga uses UNIX sockets to connect the database on your host with the code running in docker. Unfortunately, docker does not support UNIX sockets on the Mac.

For the Mac, instead, you can connect via the db host and port 3306.

• Configure your MySQL server to serve on the public IP

• Add db to /etc/hosts. Within the container, db will refer to the host. Outside it will refer to localhost

127.0.0.1        db

• Create a user and password on MySQL

$ mysql -u root -p
> CREATE USER 'user'@'%' IDENTIFIED BY 'apasswordforamysqluser';
> GRANT ALL PRIVILEGES ON *.* TO 'user'@'%';

• In your config/database.yml, you would then use:

development:
  # ...
  host: db
  username: user
  password: apasswordforamysqluser

After this, the same config/database.yml should be usable both within docker, and on the host. This works because the default configuration adds a db host that points to the host's first public address. See https://github.com/johnny-lai/beluga/blob/master/config/default.yml#L14.

All examples should be run from your rails application root folder.

$ beluga image build

$ beluga image build push

Run the following from your rails application root folder.

$ beluga exec echo "hello from devbase"
docker run --rm  -v ...:/app -v /private/tmp/mysql.sock:/private/tmp/mysql.sock -w /app -e IN_DOCKER=true -e DEV_UID=501 -e DEV_GID=20 --net=bridge   -it beluga-devbase:41a0ab20068ceedb2b15ccfa8ad1931bb9d50a4a echo hello from devbase
groupadd: GID '20' already exists
Adding user `dev' ...
Adding new user `dev' (501) with group `dialout' ...
Creating home directory `/home/dev' ...
Copying files from `/etc/skel' ...
Adding user `dev' to group `sudo' ...
Adding user dev to group sudo
Done.
hello from devbase

Run the following from your rails application root folder.

$ beluga rspec spec/your_test

$ beluga -i testbase image build

$ beluga -i testbase exec bash