pass the yml file through erb first

lib/sidekiq/cli.rb

@@ -32,6 +32,7 @@ require 'yaml'
 require 'singleton'
 require 'optparse'
 require 'celluloid'
+require 'erb'
 
 require 'sidekiq'
 require 'sidekiq/util'
@@ -208,7 +209,7 @@ module Sidekiq
     def parse_config(cli)
       opts = {}
       if cli[:config_file] && File.exist?(cli[:config_file])
-        opts = YAML.load_file cli[:config_file]
+        opts = YAML.load(ERB.new(IO.read(cli[:config_file])).result)
         queues = opts.delete(:queues) || []
         queues.each { |name, weight| parse_queues(opts, name, weight) }
       end

test/config.yml

@@ -5,5 +5,5 @@
 :pidfile:      /tmp/sidekiq-config-test.pid
 :concurrency:  50
 :queues:
-  - [often, 2]
+  - [<%="very_"%>often, 2]
   - [seldom, 1]

test/test_cli.rb

@@ -130,7 +130,7 @@ class TestCli < MiniTest::Unit::TestCase
       end
 
       it 'sets queues' do
-        assert_equal 2, Sidekiq.options[:queues].count { |q| q == 'often' }
+        assert_equal 2, Sidekiq.options[:queues].count { |q| q == 'very_often' }
         assert_equal 1, Sidekiq.options[:queues].count { |q| q == 'seldom' }
       end
     end