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':
     location => 'https://apt.dockerproject.org/repo',
     release => 'ubuntu-precise',
     repos => 'main',
     key => '58118E89F3A912897C070ADBF76221572C52609D',
     key_content => template('discourse/dockersource.gpg.key'),
     include_src => false,
   }
 
   package {'docker-engine':
-    # This version is recommended by Discourse, version 1.11 seems incompatible
-    # to Ubuntu 12.04
-    ensure => '1.8.0-0~precise',
+    ensure => '1.11.0-0~precise',
     require => Apt::Source['docker'],
   }
 
   package {'git':
     ensure => present,

[Wladimir Palant, 2016/07/08 15:46:38]

Note that this installs git 1.7.9.5 which is lower than git 1.8.0 required by
Discourse. That's the reason behind --skip-prereqs flag below - doesn't actually
seem to affect anything, it's not clear why the git version on the host matters.

   }
 
   service {'docker':
     ensure => running,
     require => Package['docker-engine'],
   }
 
   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"
+    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'],
   }
 
   exec {'rebuild':
     command => '/var/discourse/launcher rebuild app --skip-prereqs',
     user => root,
     subscribe => File['/var/discourse/containers/app.yml'],
     refreshonly => true,
     logoutput => 'on_failure',
     timeout => 0,
     require => [Exec['fetch-discourse-docker'],
                 Service['docker'],
                 Package['git']],
   }
 
   exec {'start':
     command => '/var/discourse/launcher start app --skip-prereqs',
     user => root,
-    subscribe => Exec['rebuild'],

[Wladimir Palant, 2016/07/08 15:46:38]

I still need to verify that this is working correctly and Discourse is started
under all circumstances.

[Wladimir Palant, 2016/07/10 16:42:12]

I verified that the container will always get started automatically, even on a
reboot. Still, I'm leaving the start call here just in case.

-    refreshonly => true,
+    logoutput => 'on_failure',
+    require => Exec['rebuild'],
   }
 
   class {'nginx':
     worker_connections => 500
   }
 
   nginx::hostconfig {$domain:
     source => 'puppet:///modules/discourse/site.conf',
     is_default => $is_default,
     certificate => $certificate,
     private_key => $private_key,
     log => 'access_log_intraforum'
   }
 }