Puppet users - Mar 2011 - How to get the result of a command in puppet?

Hello, I am trying to export the latest tag of an svn repository to a
puppet client.
To do so, I would like to run the following command to get the latest
tag
    /usr/bin/svn ls http://url_to_my_svn_repository/tags | /usr/bin/
tail -1

However, I couldn''t find a way to store the result of an exec in a
variable.

Since the url to the repository will change depending on the project,
I decided to use a custom function and get it to run and return the
result of the command.

    module Puppet::Parser::Functions
        newfunction(:get_latest_tag, :type => :rvalue) do |args|
            cmd = "/usr/bin/svn ls http://" + arg[0] + " |
/usr/bin/
tail -1"
            puts cmd
            puts %x[ #{cmd} ]
            puts ''the end''
        end
    end

which outputs (note that the command''s result is missing):
    /usr/bin/svn ls http://url_to_my_svn_repository/tags | /usr/bin/
tail -1

    the end

When I run the %x[#{cmd}] statement in a simple ruby file, I get the
expected result.
If I run a simple echo statement instead of the {cmd}, the result of
the cmd is actually outputted

Any idea what''s wrong in my custom function? How do I get the result
of a command in puppet?



Here is an excerpt of my manifest if you need a context.


    subversion::deploy{''my_site'':
                                repourl => ''my_site/tags'',
                                #branch => ''2011031401'',
                                copydir =>
''/var/www/my_site''
                           }


    $yedzu_svn = <<<url_to_my_svn_server>>>

    class subversion {
       package { subversion:
           ensure => installed,
       }
    }

    define subversion::workingcopy($repourl, $branch, $copydir) {
       include subversion
       file { "$copydir":
           owner => nginx, group => nginx, mode => 755,
           ensure => directory,
           #notify => subversion::checkout{$branch}
       }

       # initial check out
       subversion::checkout{
           $branch :
               repourl => $repourl,
               branch => $branch,
               copydir => $copydir,
               require => File[$copydir]
       }
    }

    define subversion::checkout($repourl, $branch, $copydir) {
       include subversion
       notice("/usr/bin/svn co --non-interactive
http://$yedzu_svn/$repourl/$branch
$copydir/$branch")
       exec { "svnco-$branch":
           command => "/usr/bin/svn co --non-interactive
http://$yedzu_svn/$repourl/$branch $copydir/$branch",
           creates => "$copydir/$branch/.svn",
           require => [Package["subversion"]]
       }
    }

    define subversion::deploy($repourl, $branch, $copydir,
$latest=false) {
       include subversion

       notice(get_latest_tag("$yedzu_svn/$repourl"))

           subversion::workingcopy {
             $branch:
               repourl => $repourl,
               branch => $branch,
               copydir => $copydir,
               #notify => subversion::symlink{$branch}
           }


       subversion::symlink{
             $branch:
               repourl => $repourl,
               branch => $branch,
               copydir => $copydir,
               require => Exec["svnco-$branch"]
           }

    }

    define subversion::symlink($repourl, $branch, $copydir){
       notice("symlinking")
           exec {
              "new_current_$copydir/$branch":
                   command => "/bin/rm $copydir/current; /bin/ln -s
$copydir/$branch $copydir/current",
           }

           exec {
              "current_$copydir/$branch":
                   command => "/bin/ln -s $copydir/$branch $copydir/
current",
           }
     } }

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On Mon, Mar 14, 2011 at 8:12 AM, duff
<etienne.dufrier@googlemail.com>wrote:
> Hello, I am trying to export the latest tag of an svn repository to a
> puppet client.
> To do so, I would like to run the following command to get the latest
> tag
>    /usr/bin/svn ls http://url_to_my_svn_repository/tags | /usr/bin/
> tail -1
>
> However, I couldn''t find a way to store the result of an exec in a
> variable.
>
> Since the url to the repository will change depending on the project,
> I decided to use a custom function and get it to run and return the
> result of the command.
>
>    module Puppet::Parser::Functions
>        newfunction(:get_latest_tag, :type => :rvalue) do |args|
>            cmd = "/usr/bin/svn ls http://" + arg[0] + " |
/usr/bin/
> tail -1"
>            puts cmd
>            puts %x[ #{cmd} ]
>            puts ''the end''
>        end
>    end
>
>
If you are actually using "puts" in your function as indicated, then
your
return value should be "nil".  Have you tried your function this way:
module Puppet::Parser::Functions
  newfunction(:get_latest_tag, :type => :rvalue) do |args|
   %x["/usr/bin/svn ls http://" + arg[0] + " | /usr/bin/tail
-1"]
  end
end

This is straight Ruby code, so the result of the function is the return
value of the last statement/expression evaluated.

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Hi Brian

The problem isn''t the lack of output from the puppet custom function. I
have
written some that return results.
I used puts statements in the example to show the absence of result from the 
%x[] statement without having to write some convoluted manifest and puppet 
output.

The %x[] statement runs and returns a result if executed on the command line 
using 
    > ruby myfile.rb

        cmd = "/usr/bin/svn ls http://url_of_my_repositorys_tags | 
/usr/bin/tail -1"
        puts cmd
        puts %x[ #{cmd} ]

    outputs:
        my_tag_name/

Any ideas why the same command would stop running once wrapped in puppet?
If I run it using system(), I get "True" as the result, but
that''s not what
I want

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In that case I''ve got nothing.  Sorry.

On Mar 15, 2011, at 6:37 AM, duff wrote:
> Hi Brian
> 
> The problem isn''t the lack of output from the puppet custom
function. I have written some that return results.
> I used puts statements in the example to show the absence of result from
the %x[] statement without having to write some convoluted manifest and puppet
output.
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