apt: Always enable backports repo with lower priority

See https://help.ubuntu.com/community/UbuntuBackports#Configuring_Backports_for_Manual_Install

apt/manifests/init.pp

@@ -85,14 +85,9 @@ define apt::ppa($ensure = "present") {
 #       Base URL of security repository.
 #       Defaults to "mirror://mirrors.ubuntu.com/mirrors.txt".
 #
-#   $backports:
-#       Boolean for enabling the backports repositories.
-#       Defaults to true.
-#
 class apt::sources(
     $archive_url="mirror://mirrors.ubuntu.com/mirrors.txt",
-    $security_url="mirror://mirrors.ubuntu.com/mirrors.txt",
-    $backports=true
+    $security_url="mirror://mirrors.ubuntu.com/mirrors.txt"
 ) {
 
     tag("bootstrap")
@@ -108,6 +103,16 @@ class apt::sources(
         notify  => Exec["apt-get-update"],
     }
 
+    if $::operatingsystem == "Ubuntu" and versioncmp($::operatingsystemrelease, "11.04") < 0 {
+        file { "/etc/apt/preferences.d/backports.pref":
+            ensure  => present,
+            mode    => "0644",
+            owner   => "root",
+            group   => "root",
+            content => "Package: *\nPin: release a=${::lsbdistcodename}-backports\nPin-Priority: 100\n",
+        }
+    }
+
 }
 
 

apt/templates/sources.list.erb

@@ -6,8 +6,6 @@ deb-src <%= @archive_url %> <%= @lsbdistcodename %>-updates main restricted univ
 
 deb <%= @security_url %> <%= @lsbdistcodename %>-security main restricted universe multiverse
 deb-src <%= @security_url %> <%= @lsbdistcodename %>-security main restricted universe multiverse
-<% if @backports == true -%>
 
 deb <%= @archive_url %> <%= @lsbdistcodename %>-backports main restricted universe multiverse
 deb-src <%= @archive_url %> <%= @lsbdistcodename %>-backports main restricted universe multiverse
-<% end -%>