29 Jul 2014

Capistrano 3 deploy for ":deploy_via, :copy" orphans

Capistrano 2 had a feature that enabled deploy by copying the project tarball to the remote server instead of git cloning it from the remote server, Capistrano 3 doesn’t had this feature. The problem of cloning it from the remote server is that sometimes the remote server doesn’t have access to the git repository and adding access to it is not desirable.

Just a note, or rant: Capistrano isn’t a good example of well documented project and Ruby doesn’t have clear semantic on what is public API and what should be considered private API, so I’m not 100% what I did is a hack or a honest use of their API. Anyway this works with Capistrano 3.2.1.

The code, hack, solution, whatever you call it

In Capistrano 2 times the elders of Google told me that a “set :deploy_via, :copy” should be enough to do the job, with Capistrano 3 Google just says it’s possible with few lines of code, but doesn’t say how.

The code bellow is in deploy.rb, hope you understand how it works by reading the comments.

# This is important, since the solution was tested only with 3.2.1
lock '3.2.1'

set :application, 'Hello'
# We will tell a white lie to Capistrano
set :scm, :git

# release id is just the commit hash used to create the tarball.
set :project_release_id, `git log --pretty=format:'%h' -n 1 HEAD`
# the same path is used local and remote... just to make things simple for who wrote this.
set :project_tarball_path, "/tmp/#{fetch(:application)}-#{fetch(:project_release_id)}.tar.gz"

# We create a Git Strategy and tell Capistrano to use it, our Git Strategy has a simple rule: Don't use git.
module NoGitStrategy
  def check

  def test
    # Check if the tarball was uploaded.
    test! " [ -f #{fetch(:project_tarball_path)} ] "

  def clone

  def update

  def release
    # Unpack the tarball uploaded by deploy:upload_tarball task.
    context.execute "tar -xf #{fetch(:project_tarball_path)} -C #{release_path}"
    # Remove it just to keep things clean.
    context.execute :rm, fetch(:project_tarball_path)

  def fetch_revision
    # Return the tarball release id, we are using the git hash of HEAD.

# Capistrano will use the module in :git_strategy property to know what to do on some Capistrano operations.
set :git_strategy, NoGitStrategy

# Finally we need a task to create the tarball and upload it,
namespace :deploy do
  desc 'Create and upload project tarball'
  task :upload_tarball do |task, args|
    tarball_path = fetch(:project_tarball_path)
    # This will create a project tarball from HEAD, stashed and not committed changes wont be released.
   `git archive -o #{tarball_path} HEAD`
    raise 'Error creating tarball.'if $? != 0

    on roles(:all) do
      upload! tarball_path, tarball_path

# Attach our upload_tarball task to Capistrano deploy task chain.
before 'deploy:updating', 'deploy:upload_tarball'

This worked for me™.

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