same crontab on multiple servers

bin/whenever_server

@@ -0,0 +1,38 @@
+#!/usr/bin/env ruby
+
+require 'whenever'
+require 'redis'
+
+options = {}
+
+OptionParser.new do |opts|
+  opts.banner = "Usage: whenever [options]"
+
+  opts.on('-f', '--load-file [schedule file]', 'Default: config/schedule.rb') do |file|
+    options[:file] = file if file
+  end
+end.parse!
+
+job_list = Whenever::JobList.new(file: options[:file] || 'config/schedule.rb')
+
+puts(false) unless job_list.redis_options
+
+redis = Redis.new(job_list.redis_options)
+
+# redis key
+lock = :whenever_server
+
+# get the server that has the lock
+whenever_server = redis.get lock
+
+# if there is no server with the lock, give the lock to the current server
+if whenever_server.nil?
+  redis.multi do
+    redis.setnx lock, Socket.gethostname
+    # expire hourly
+    redis.expire lock, 3600
+  end
+end
+
+# return true/false if the current server should be running the task or not
+puts redis.get(lock) == Socket.gethostname

lib/whenever/job_list.rb

@@ -21,6 +21,8 @@ def initialize(options)
         File.read(options[:file])
       end
 
+      @options = options
+
       instance_eval(setup, setup_file)
       instance_eval(schedule, options[:file] || '<eval>')
     end
@@ -48,6 +50,9 @@ def job_type(name, template)
       singleton_class_shim.class_eval do
         define_method(name) do |task, *args|
           options = { :task => task, :template => template }
+
+          options[:template] = "cd :path && if whenever_server #{ "-f #{@options[:file]}" if @options[:file] && @options[:file] != 'config/schedule.rb'} >> /dev/null ; then #{options[:template]} ; fi" if @redis_options
+
           options.merge!(args[0]) if args[0].is_a? Hash
 
           # :cron_log was an old option for output redirection, it remains for backwards compatibility

lib/whenever/setup.rb

@@ -9,6 +9,9 @@
 # http://blog.scoutapp.com/articles/2010/09/07/rvm-and-cron-in-production
 set :job_template, "/bin/bash -l -c ':job'"
 
+# Multiple servers support
+set :redis_options, nil
+
 set :runner_command, case
   when Whenever.bin_rails?
     "bin/rails runner"

test/functional/output_whenever_server_test.rb

@@ -0,0 +1,16 @@
+require 'test_helper'
+
+class OutputWheneverServer < Whenever::TestCase
+  test 'command when the redis_options is set' do
+    output = Whenever.cron \
+    <<-file
+      set :redis_options, :url => 'redis://localhost:6379/1'
+      every :hour do
+        set :path, "/tmp"
+        command "blahblah"
+      end
+    file
+
+    assert_match "0 * * * * /bin/bash -l -c 'cd /tmp && if whenever_server >> /dev/null ; then blahblah ; fi'", output
+  end
+end

whenever.gemspec

@@ -18,7 +18,7 @@ Gem::Specification.new do |s|
   s.require_paths = ["lib"]
 
   s.add_dependency "chronic", ">= 0.6.3"
-
+  s.add_dependency "redis"
   s.add_development_dependency "mocha", ">= 0.9.5"
   s.add_development_dependency "rake"
   s.add_development_dependency "minitest"