Capistrano::Dockerbuild

Capistrano tasks for docker build on remote server.

These tasks depends on Git. And so remote server must have git command.

Add this line to your application's Gemfile:

gem 'capistrano-dockerbuild'

And then execute:

$ bundle

Or install it yourself as:

$ gem install capistrano-dockerbuild

Add require and install_plugin to Capfile.

require 'capistrano/dockerbuild'
install_plugin Capistrano::Dockerbuild

# deploy.rb

set :application, :sample_project

set :repo_url, 'git@github.com:example/example.git'

set :git_sha1, `git rev-parse HEAD`.chomp

set :branch, fetch(:git_sha1)

set :ssh_user, ENV["SSH_USER"] || ENV["USER"] || Etc.getlogin

set :ssh_options, {
  user: fetch(:ssh_user),
  port: 22,
  use_agent: true,
}

# add :docker_build role to server definition
# add :arch property to server definition
server "docker-build-amd64.example.com", roles: [:docker_build], ssh_options: fetch(:ssh_options), arch: "amd64"
server "docker-build-arm64.example.com", roles: [:docker_build], ssh_options: fetch(:ssh_options), arch: "arm64"

set :docker_registry, "ghcr.io"
set :docker_build_base_dir, "/home/#{fetch(:ssh_user)}/#{fetch(:application)}"

# if docker_build_cmd is proc and has more than 1 arity, pass host object.
set :docker_build_cmd, ->(host) {
  [:docker, "build", "-f", "Dockerfile", "-t", fetch(:docker_tag_with_arch).call(host), "--build-arg", "host=#{host}", "."]
}
set :docker_tag, "ghcr.io/NAMESPACE/IMAGE_NAME:#{fetch(:git_sha1)}"

If any servers have arch property, this plugin enables multi architecture mode.

The behavior of multi architecture mode is following.

1. build image with a arch suffix like -amd64
2. push the image
3. create a manifest list of pushed images and push it on first server

Use common variables

• repo_url
• branch

If you want to use GitHub Apps installation access token or something to authorize repository access using HTTPS protocol. You can set variables in your config/deploy.rb:

set :git_http_username, -> { ENV["GIT_HTTP_USERNAME"] }
set :git_http_password, -> { ENV["GIT_HTTP_PASSWORD"] }
set :repo_url, -> do
  if fetch(:git_http_username) && fetch(:git_http_password)
    "https://github.com/owner/repo.git"
  else
    "git@github.com:owner/repo.git"
  end
end

Update remote URL always if you set proper value to all of repo_url, git_http_username, and git_http_password.

• Ensure #{docker_build_base_dir}
• Ensure git reachable

• Clone repo to #{docker_build_base_dir} as mirror

• git remote update #{docker_build_base_dir}

• Create #{branch} worktree to #{docker_tag}-#{timestamp}
• With in worktree dir, execute #{docker_build_cmd}
• Clear worktree

• docker push #{docker_tag}

• Remove docker images
• Leave keep_docker_image_count images
• Remove from the oldest image

docker:push => docker:build => docker:update_mirror => docker:clone => docker:check

After checking out the repo, run bin/setup to install dependencies. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/reproio/capistrano-dockerbuild.

The gem is available as open source under the terms of the MIT License.