Issue 4234 - Migrate Discourse to a Docker-based setup

modules/discourse/manifests/init.pp

 class discourse(
     $domain,
     $certificate,
     $private_key,
     $site_settings,
     $is_default = false,
     $admins = hiera('discourse::admins', [])
   ) {
 
   apt::source {'docker':
@@ skipping 20 matching lines @@
   }
 
   file {'/var/discourse':
     ensure => directory,
     mode => 755,
     owner => root,
     group => root
   }
 
   exec {'fetch-discourse-docker':
-    command => "hg clone https://hg.adblockplus.org/discourse_docker /var/discourse",
+    command => "git clone https://github.com/discourse/discourse_docker.git /var/discourse",
     path => ["/usr/bin/", "/bin/"],
     user => root,
     timeout => 0,
-    require => [Package['mercurial'], File['/var/discourse']],
-    onlyif => "test ! -d /var/discourse/.hg"

[mathias, 2016/07/13 17:48:03]

Using exec resource parameter "unless" is more straightforward than negation
with "onlyif", in general, and in this case one may even prefer using parameter
"creates" instead (assuming the explicit test for being a directory having not
much more value than a general test for existence).

[Wladimir Palant, 2016/07/13 18:01:12]

The more important question is whether we should even use our copy of the
repository here given that Discourse assumes Git (particularly to verify that
the discourse_docker checkout is up to date) and will check out several
repositories from GitHub within the container anyway (meaning: if GitHub is down
then it won't work regardless).

+    require => [Package['git'], File['/var/discourse']],
+    unless => "test -d /var/discourse/.git"
   }
 
   file {'/var/discourse/containers/app.yml':
     ensure => file,
     mode => 600,
     owner => root,
     group => root,
     content => template('discourse/app.yml.erb'),
     require => Exec['fetch-discourse-docker'],
   }
@@ skipping 22 matching lines @@
   }
 
   nginx::hostconfig {$domain:
     source => 'puppet:///modules/discourse/site.conf',
     is_default => $is_default,
     certificate => $certificate,
     private_key => $private_key,
     log => 'access_log_intraforum'
   }
 }