rake task to build a WAR using warbler. The idea being that a YAML file has multiple 'production' configurations but you need to select one when building a WAR for a certain production environment. You can do that by running: rake build_war[some_environme

app-config.yml

%YAML 1.1
---
! "defaults":
  ! "cache": &7000
    ! "username": ""
    ! "password": ""
    ! "servers": ["localhost:11211"]
! "development":
  ! "cache": *7000
! "prod-server-a"
  ! "cache":
    ! "username": "prod-user"
    ! "password": "prod-password"
    ! "servers": ["prod-a.acme.com:11211"]
! "prod-server-b"
  ! "cache": 
    ! "username": "prod-user"
    ! "password": "prod-password"
    ! "servers": ["prod-b.acme.com:56555"]

gistfile1.rb

require 'yaml'

def set_production_environment(source_environment, config, output_yaml)
	config['production'] = config[source_environment]
	
	File.open(output_yaml, 'w') do |out|
		YAML.dump(config, out)
	end
end

def get_usage_msg(config)
	"Usage: rake #{t}[#{config.keys.join('|')}]"
end

desc "Build the WAR file"
task :build_war, :environment do |t, args|
	CONFIG_FILE = 'config/app-config.yml'
	environment = args[:environment]
	
	# load config
	config = YAML.load_file CONFIG_FILE
	
	# check given 'environment' exists in config
	raise get_usage_msg if (environment.nil? or environment.empty?)
	raise "Invalid option=#{environment}. #{get_usage_msg(config)}" unless config.has_key? environment
	
	# backup the original config file
	cp CONFIG_FILE, CONFIG_FILE + '.bak'
	
	`warble`
	raise "failed to build WAR: #{$?.inspect}" unless $?.success?
	
	mv "web.war", "myapp-#{environment}.war"
	
	# restore the config
	mv CONFIG_FILE + '.bak', CONFIG_FILE
end

Say you want to build a 'production' WAR file using warbler but you need the production rails environment to use prod-server-b. Using the rake task above you would do something like this:

rake build_war[prod-server-b]

You would end up with a WAR file named: myapp-prod-server-a.war (assuming you used the rake file "as is", you should tweak it as necessary for your own project of course).