Capistrano::Container

Helps managing docker container and files inside docker container for Capistrano 3.x.

This project is in an early stage but helps me alot dealing with my container deployments and keeps my code clean. It is not only ment for docker, but at the moment there only supports docker, feel free to ditribute =)

This gem does not handle Dockerfiles or such things, for that there are enough capistrano modules available.

Installation

Add this line to your application's Gemfile:

gem 'capistrano', '>= 3.0.0'
gem 'capistrano-container'

And then execute:

$ bundle

Or install it yourself as:

$ gem install capistrano-container

Dont forget to require the module in your Capfile:

require 'capistrano/container'

Usage

definition

To define and register a container do the following in you stage config or deploy.rb:

...

server('www.example.com', user: 'root', roles: %w{web})

container 'db',  roles: %w{db},
                 container_id: 'website_company_beta_db',
                 server: ['www.example.com']

container 'php', roles: %w{php},
                 container_id: 'website_company_beta_php',
                 server: ['www.example.com']

...

This registers two container (db, php) for the server www.example.com. The roles can later be used to filter container like the way you filter server in capistrano.

The container id is optional. If not set the ontainer id is equal to the name you give the container as first argument. The container id will later be used to run docker commands.

If you define a container, the given hosts get the role :container_host behind the scenes, so you can filter hosts that running container. Also a container specific role will be added, fo container named php :container_php.

commandline tasks

There are general tasks you can run, if needed you will be asked on which container_id the command should run.

cap container:all                  # show all docker containers
cap container:delete               # delete a docker container
cap container:diff                 # show FS diffs of docker container
cap container:events               # show events of docker container
cap container:inspect              # show info of docker container
cap container:logs                 # show logs of docker container
cap container:pause                # pause a docker container
cap container:ports                # show shows public facing port of docker container
cap container:ressources           # show resource usage statistics of docker container
cap container:restart              # restart a docker container
cap container:running              # show running docker containers
cap container:stop                 # stop a docker container
cap container:top                  # show running processes of docker container
cap container:unpause              # unpause a docker container
cap container:update_docker        # update docker

For every registered container also specific tasks will be registered. For a container named php the following tasks will be available. (With cap -T you will the container specific tasks only see if you register your container in the deploy.rb)

cap container:php:delete           # delete a docker container
cap container:php:diff             # show FS diffs of docker container
cap container:php:events           # show events of docker container
cap container:php:inspect          # show info of docker container
cap container:php:logs             # show logs of docker container
cap container:php:pause            # pause a docker container
cap container:php:ports            # show shows public facing port of docker container
cap container:php:ressources       # show resource usage statistics of docker container
cap container:php:restart          # restart a docker container
cap container:php:stop             # stop a docker container
cap container:php:top              # show running processes of docker container
cap container:php:unpause          # unpause a docker container

ruby tasks

You can access the defined container like this:

after :deploy, :updated do
  on roles :web do
    # do your application restarts
  end

  on_container_roles :php do |container, host|
    container.invoke 'restart'
  end
end

This filter container with the role :php and invokes the task container:#{container.name}:restart.

Or inside other tasks

  container = container_by_name :db
  container = container_by_roles :php
  container = container_by_id 'website_company_beta_db'

A container instance has the following methods:

  # tests if the container has a specific role
  def has_role?(role)

  # the docker container id if configured, the container name instead
  def container_id

  # the container specific role, for a container named php `:container_php`
  def container_role

  # uploads a local file to a temp file on host /tmp, then copies the file into the container with docker cp
  def upload!(src, target)

  # doenloads a container file to host /tmp and then to a local file
  def download!(src, target)

  # executes a command on the docker container with docker exec
  def execute(command)

  # invokes a container specific task
  def invoke(task_name)

TODO

• Implement provider pattern for other container manager.
• Write tests.

Changes

Version 0.0.2

• Initial release

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request