From: "Ara.T.Howard" <Ara.T.Howard@...>
Date: 2005-08-19T08:53:37+09:00
Subject: Re: domain-specific language

On Fri, 19 Aug 2005, Joe Van Dyk wrote:

> I'm writing an application that controls a group/cluster of linux
> computers/nodes.  I need to have a configuration file that lists the
> nodes in the cluster.
>
> It would be neat if the configuration file was in Ruby.  If I had
> nodes named node1 and node3, the configuration file could look a
> little like:
>
> node :node1 do
>  ip 192.whatever
>  title "Node 1"
> end
>
> node :node2 do
>  ip 192.whatever
>  title "Node 2"
> end
>
> So, is there some standard Ruby idiom for how to read a file and
> execute the code?  Just load the file and instance_eval it?


     harp:~ > cat a.rb
     config = <<-config
       nodes :
         1 :
           ip    : 192.whatever
           title : node 1
         2 :
           ip    : 192.whatever
           title : node 2
     config

     require 'yaml'

     config = YAML::load config

     config['nodes'].each do |nid, node|
       puts "node <#{ nid }> => <#{ node.inspect }>"
     end


     harp:~ > ruby a.rb
     node <1> => <{"title"=>"node 1", "ip"=>"192.whatever"}>
     node <2> => <{"title"=>"node 2", "ip"=>"192.whatever"}>

so all you have to do is 'YAML::load(IO::read(configfile))'.

what kind of clustering are you working with?

you may, or may not, find this useful:

   http://raa.ruby-lang.org/project/rq/
   http://www.linuxjournal.com/article/7922

cheers.

-a
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