Capistrano::Dockerbuild

Capistrano tasks for docker build on remote server.

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

Installation

Add this line to your application's Gemfile:

gem 'capistrano-dockerbuild'

And then execute:

$ bundle

Or install it yourself as:

$ gem install capistrano-dockerbuild

Usage

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

Variables

Common Variables

Use common variables

• repo_url
• branch

name	required	default	desc
docker_build_base_dir	yes	nil	Repository clone to here, and execute build command here
docker_build_cmd	no	->(host) { [:docker, :build, "-t", fetch(:docker_tag_with_arch).call(host), "."] }	Execute command for image building
docker_tag	no	-> { fetch(:application) + ":" + fetch(:branch) }	Use by docker tag repository:{{docker_tag}}
docker_latest_tag	no	false	Add latest tag to building image
keep_docker_image_count	no	10
git_http_username	no	nil	See below
git_http_password	no	nil	See below

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.

Tasks

docker:check

• Ensure #{docker_build_base_dir}
• Ensure git reachable

docker:clone

• Clone repo to #{docker_build_base_dir} as mirror

docker:update_mirror

• git remote update #{docker_build_base_dir}

docker:build

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

docker:push

• docker push #{docker_tag}

docker:cleanup_local_images

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

Task Dependency

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

Development

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.

Contributing

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

License

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