Dynamically generate a chef Berksfile from an existing Chef Policyfile.rb

Berksfile

require 'chef-cli/policyfile_services/install'

def policyfile_to_berksfile(policyfile_path)
  pf = ChefCLI::PolicyfileServices::Install
         .new(policyfile: policyfile_path)
         .policyfile_compiler

  # ------------------------------------------------------------------
  # 1. Sources
  # ------------------------------------------------------------------
  sources = pf.default_source.map do |source|
    case source
    when ChefCLI::Policyfile::CommunityCookbookSource
      %(source "#{source.uri}")
    when ChefCLI::Policyfile::ChefServerCookbookSource
      %(source :chef_server, "#{source.uri}")
    end
  end.compact

  # ------------------------------------------------------------------
  # 2. Cookbooks
  # ------------------------------------------------------------------
  current_cb = pf.dsl.name
  cookbooks  = pf.fixed_version_cookbooks_specs.map do |name, spec|
    next if name == current_cb

    case spec.source_type
    when :path
      %(cookbook '#{name}', path: '#{spec.source_options[:path]}')

    when :git, :github
      build_git_line(name, spec.source_type, spec.source_options)

    else
      nil
    end
  end.compact

  # ------------------------------------------------------------------
  # 3. Result
  # ------------------------------------------------------------------
  (sources + cookbooks + ['metadata']).join("\n")
end

# --------------------------------------------------------------------
# Helper: build a line for git / github sources
# --------------------------------------------------------------------
def build_git_line(name, type, opts)
  # 1. Work out which form of the location we have
  owner_repo =
    opts[:github] ||
    owner_repo_from_url(opts[:git])

  if owner_repo                    # short form → github:
    key  = :github
    val  = owner_repo
  else                             # everything else → git:
    key  = :git
    val  = opts[:git]
  end

  raise "Cannot determine repository for cookbook #{name}" if val.to_s.empty?

  # 2. Put together the pin (ref / branch / tag)
  parts = ["#{key}: '#{val}'"]
  if (sha = opts[:revision] || opts[:ref])
    parts << "ref: '#{sha}'"
  elsif opts[:branch]
    parts << "branch: '#{opts[:branch]}'"
  elsif opts[:tag]
    parts << "tag: '#{opts[:tag]}'"
  end

  "cookbook '#{name}', #{parts.join(', ')}"
end

# --------------------------------------------------------------------
# Pull "owner/repo" out of a GitHub URL if we need to
# --------------------------------------------------------------------
def owner_repo_from_url(url)
  return unless url

  # https://github.com/BuyerQuest/aws.git
  # git://github.com/BuyerQuest/aws.git
  # ssh://[email protected]/BuyerQuest/aws.git
  if url =~ %r{\A(?:https?|git|ssh)://(?:[^@/]+@)?github\.com/([^/]+/[^/]+?)(?:\.git)?\z}i
    return Regexp.last_match(1)
  end

  # [email protected]:BuyerQuest/aws.git
  if url =~ %r{\Agit@github\.com:([^/]+/[^/]+?)(?:\.git)?\z}i
    return Regexp.last_match(1)
  end
end

# --------------------------------------------------------------------
# Kick things off
# --------------------------------------------------------------------
policyfile_path = File.expand_path('../Policyfile.rb', __FILE__)
eval(policyfile_to_berksfile(policyfile_path))