Add chef search capability when using roles in capistrano Tasks

chef-capistrano-init.rb

require 'rubygems'
require 'chef/client'
require 'chef/run_status'
require 'ohai'
require 'chef/mixin/language'

# Override the default role search in capistrano
# can be used to combine chef searches in capistrano land:
# task :master_update,  :roles => 'recipes:chef\:\:server' do
# ...
# end

module Capistrano::Configuration::Servers
  # Attempts to find all defined servers that match the given criteria.
  # The options hash may include a :hosts option (which should specify
  # an array of host names or ServerDefinition instances), a :roles
  # option (specifying an array of roles), an :only option (specifying
  # a hash of key/value pairs that any matching server must match),
  # an :exception option (like :only, but the inverse), and a
  # :skip_hostfilter option to ignore the HOSTFILTER environment variable
  # described below.
  #
  # Additionally, if the HOSTS environment variable is set, it will take
  # precedence over any other options. Similarly, the ROLES environment
  # variable will take precedence over other options. If both HOSTS and
  # ROLES are given, HOSTS wins.
  #
  # Yet additionally, if the HOSTFILTER environment variable is set, it
  # will limit the result to hosts found in that (comma-separated) list.
  #
  # If the HOSTROLEFILTER environment variable is set, it will limit the
  # result to hosts found in that (comma-separated) list of roles
  #
  # Usage:
  #
  # # return all known servers
  # servers = find_servers
  #
  # # find all servers in the app role that are not exempted from
  # # deployment
  # servers = find_servers :roles => :app,
  # :except => { :no_release => true }
  #
  # # returns the given hosts, translated to ServerDefinition objects
  # servers = find_servers :hosts => "[email protected]"
  def find_servers(options={})
    return [] if options.key?(:hosts) && (options[:hosts].nil? || [] == options[:hosts])
    return [] if options.key?(:roles) && (options[:roles].nil? || [] == options[:roles])
    
    hosts = server_list_from(ENV['HOSTS'] || options[:hosts])
    
    if hosts.any?
      if options[:skip_hostfilter]
        hosts.uniq
      else
        filter_server_list(hosts.uniq)
      end
    else
      roles = role_list_from(ENV['ROLES'] || options[:roles] || self.roles.keys)

      roles = roles & Array(options[:roles]) if preserve_roles && !options[:roles].nil?

      only = options[:only] || {}
      except = options[:except] || {}
      
      # BOH
      # Override role definition
      @chef_search_facility ||= SearchHelper.new
      # servers = roles.inject([]) { |list, role| list.concat(self.roles[role] || []) }
      servers = roles.inject([]) { |list, role| 
        if ! self.roles.has_key?(role)
          # If the role is missing create it on the fly and keep on working
          role(role, *@chef_search_facility.search(:node, role).map {|n| n[:hostname]})
        end
        list.concat(self.roles[role] || []) 
      }
      # EOH


      servers = servers.select { |server| only.all? { |key,value| server.options[key] == value } }
      servers = servers.reject { |server| except.any? { |key,value| server.options[key] == value } }

      if options[:skip_hostfilter]
        servers.uniq
      else
        filter_server_list(servers.uniq)
      end
    end
  end
end


# Boot Chef system
Chef::Config.from_file("/etc/chef/client.rb")
Chef::Log.level :info
ohai = Ohai::System.new()
ohai.all_plugins
@node_name ||= ohai[:fqdn] ? ohai[:fqdn] : ohai[:hostname]
Chef::Config[:node_name] = @node_name
c = Chef::Client.new()
c.run_ohai
node = c.build_node



# the search helper can be used inside capistrano to allow the usage of the Chef mixin methods
# set :chef_searcher, SearchHelper.new
# ...
# chef_server.search(:node, "")
#
class SearchHelper
  include Chef::Mixin::Language
end

require inside your capistrano file to activate. Use later as described in the source code. Share and have fun !