Capistrano variables

Posted by Dr Nic on April 10, 2007

Here’s an example of how you can pass variables to your capistrano actions via the cap command.

So, the above action could be called as follows:

cap log
cap log -s lines=1000
cap log -s rails_env=test

For reference, you pass values to Rake tasks via environment variables:

rake db:migrate RAILS_ENV=test

Inside the db:migrate task, you’d retrieve the value ‘test’ via ENV['RAILS_ENV'].

And further more, this then compares to how you’d normally pass option values into normal command-line apps:

tail -n 1000 log/production.log

Who said the unix command line wasn’t easy peasy. Bah.

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  1. atmos Wed, 11 Apr 2007 05:20:26 UTC

    Nice! I hadn’t used that before.

  2. topfunky Wed, 11 Apr 2007 06:37:08 UTC

    Actually, you don’t even need the configuration.variables part! It’s almost as magic as Dr. Nic’s models.

    Anything passed with dash-s becomes a local variable in your Capistrano recipes.

  3. Dr Nic Wed, 11 Apr 2007 06:53:25 UTC

    @topfunky - that’s how I thought it should work too. But it wasn’t working, hence hunting down configuration.variables hash.

    Here’s the same action using local variables:

    task :log do
  lines ||= 100
  rails_env ||= 'production'
  # lines     = configuration.variables[:lines] || 100
  # rails_env = configuration.variables[:rails_env] || 'production'
  env   = ENV['RAILS_ENV'] || 'production'
  run "tail -n #{lines} #{deploy_to}/#{shared_dir}/log/#{rails_env}.log" do |ch, stream, out|
    puts out
  end
end

    But when I run cap log -s lines=10 it still looks for the default 100.

    I’ll ping it to the capistrano mailing list/Jamis and see if anyone can reproduce this.

  4. choonkeat Wed, 11 Apr 2007 07:17:29 UTC

    I have a “ask” method in my capistrano instead: http://pastie.caboo.se/52993

    So I’ll do

    ask :server_port, "Port number", "3000"
    puts server_port

    If the value is given at command line via -S server_port=5000 then it won’t ask, otherwise prompt.

  5. Sergio Espeja Wed, 11 Apr 2007 10:48:17 UTC

    Very useful!

    This is a good capistrano variables example and also a very useful recipe!

    I’ve started using this recipe and blogged it in spanish at my blog: http://spejman.blogspot.com/2007/04/logs-del-servidor-con-capistrano.html

    Thanks for your post!

  6. Dr Nic Wed, 11 Apr 2007 13:07:45 UTC

    @all - see http://groups.google.com/group/capistrano/browse_thread/thread/d4d30393b6f41605 for discussion about the mysterious #lines variable/method.

  7. Wayne Seguin Sat, 14 Apr 2007 15:59:02 UTC

    Nic,

    Please read my reply:

    http://groups.google.com/group/capistrano/browse_thread/thread/d4d30393b6f41605

    Thanks,
    ~Wayne

  8. topfunky Mon, 09 Jul 2007 22:44:21 UTC

    In Cap2 this appears to be just ‘variables’ instead of ‘configuration.variables’.

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