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
  
  # Extract 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}\""
    else
      nil
    end
  end.compact
  
  # Extract cookbooks, excluding the current cookbook
  current_cookbook_name = pf.dsl.name
  cookbooks = pf.fixed_version_cookbooks_specs.map do |name, spec|
    next if name == current_cookbook_name

    case spec.source_type
    when :path
      "cookbook '#{name}', path: '#{spec.source_options[:path]}'"
    when :git, :github
      "cookbook '#{name}', git: '#{spec.source_options[:git]}'"
    else
      nil
    end
  end.compact
  
  # Create Berksfile content
  (sources + cookbooks + ["metadata"]).join("\n")
end

# Define the path to the Policyfile
# This makes the assumption that you're only interested in a single policyfile.
# That works fine for me, but you may have other needs. Modify appropriately.
policyfile_path = File.expand_path('../Policyfile.rb', __FILE__)

# Generate and evaluate the Berksfile content
eval(policyfile_to_berksfile(policyfile_path))