cookbook reverse dependency lookup

Cookbook dependency reverse lookup.rb

Its a cookbook class that we use to abstract cookbooks and their
dependencies. The key method to look at is dependency_hash which creates
a hash based on the dependencies of the cookbook.

We do not explicitly do a reverse dependency lookup but we can use this
hash to infer a change in dependencies from a change in any cookbook in
an environment. So the flow is:

1. I change cookbook A and it gets sent to the chef server and indexed
in berks.
2. We do a berks update on the environment cookbook.
3. We invoke the kitchen builds for each cookbook in the environment
4. Each of these cookbooks checks to see if their dependency hash as
calculated by all the current berks changes from #2 above is now
different from the one we store in our LKG_{environment name}
environment that stores the hash of the cookbook as it was ehwn it last
passed its kitchen test.

Hope this makes sense.




require 'berkshelf'
require 'digest/sha1'
require 'json'

module Promote
  class Cookbook
    def initialize(cookbook_name, config)
      @name = cookbook_name
      @config = config
      @metadata_path = File.join(path, 'metadata.rb')
      @berks_path = File.join(path, "Berksfile")
    end

    def dependencies
      @dependencies ||= get_synced_dependencies_from_lockfile
    end

    def metadata_dependencies
      metadata.dependencies
    end

    def version(version=nil)
      metadata.version
    end

    def version=(version)
      version_line = raw_metadata[/^\s*version\s.*$/]
      current_version = version_line[/('|").*("|')/].gsub(/('|")/,"")
      if current_version != version.to_s
        new_version_line = version_line.gsub(current_version, version.to_s)
        new_content = raw_metadata.gsub(version_line, new_version_line)
        save_metadata(new_content)
      end
      version
    end

    def stamp_commit(commit)
      commit_line = "#sha1 '#{commit}'"
      new_content = raw_metadata.gsub(/#sha1.*$/, commit_line)
      if new_content[/#sha1.*$/].nil?
        new_content += "\n#{commit_line}"
      end
      save_metadata(new_content)
    end

    def raw_metadata
      @raw_metadata ||= File.read(@metadata_path)
    end

    def metadata
      @metadata ||=get_metadata_from_file
    end

    def path
      File.join(@config.cookbook_directory, @name)
    end

    def sync_berksfile(update=false)
      return if berksfile.nil?

      update = false unless File.exist?("#{@berks_path}.lock")
      update ? berksfile_update : berksfile.install
    end

    def dependencies_changed_after_update?
      old_deps = dependencies
      sync_berksfile(true)
      new_deps = get_dependencies_from_lockfile

      return true unless old_deps.count == new_deps.count

      old_deps.each do |k,v|
        if k != @name
          return true unless new_deps[k] == v
        end
      end

      return false
    end

    def dependency_hash(environment_cookbook_name)
      sync_latest_app_cookbooks(environment_cookbook_name)
      hash_src = ''
      dependencies.each do | k,v |
        hash_src << "#{k}::#{v}::"
      end
      Digest::SHA1.hexdigest(hash_src)
    end

    def sync_latest_app_cookbooks(environment_cookbook_name)
      result = {}
      latest_server_cookbooks = Utils.chef_server_cookbooks(@config, 1)
      env_cookbook = Cookbook.new(environment_cookbook_name, @config)
      env_cookbook.metadata_dependencies.each do |key|
        cb_key = key[0]
        next if cb_key == @name || !latest_server_cookbooks.has_key?(cb_key)
        latest_version = latest_server_cookbooks[cb_key]['versions'][0]['version']
        if dependencies.keys.include?(cb_key) && latest_version > dependencies[cb_key].to_s
          berksfile_update(cb_key)
          result[cb_key] = latest_version
        end
      end
      result
    end

    private

    def berksfile
      @berksfile ||= get_berksfile
    end

    def save_metadata(content)
      File.open(@metadata_path, 'w') do |out|
        out << content
      end
      @metadata=nil
      @raw_metadata = nil
    end

    def get_metadata_from_file
      metadata = Chef::Cookbook::Metadata.new
      metadata.from_file(@metadata_path)
      metadata
    end

    def get_synced_dependencies_from_lockfile
      berksfile.install
      get_dependencies_from_lockfile
    end

    def get_dependencies_from_lockfile
      berks_deps = berksfile.list
      deps = {}

      berks_deps.each {|dep| deps[dep.name] = dep.locked_version}
      deps
    end

    def get_berksfile
      return unless File.exist?(@berks_path)
      Berkshelf.set_format :null
      Berkshelf::Berksfile.from_file(@berks_path)
    end

    def berksfile_update(cookbooks = nil)
      cookbooks.nil? ? berksfile.update : berksfile.update(cookbooks)
      @dependencies = nil
    end
  end
end