Add support for Ubuntu 20.04

Since Ubuntu 16.04 the plugins package is `monitoring-plugins-basic` but
a metapackage named `nagios-plugins-basic` (which install the former) is
maintained. In Ubuntu 20.04 this metapackage does not exist.

Author: amateo

README.md

@@ -24,6 +24,10 @@ It is tested on the following platforms.
 * Solaris 10
 * Solaris 11
 * Ubuntu 12
+* Ubuntu 14.04
+* Ubuntu 16.04
+* Ubuntu 18.04
+* Ubuntu 20.04
 
 ===
 

manifests/init.pp

@@ -116,7 +116,10 @@
           $default_nrpe_package                     = 'nagios-nrpe-server'
           $default_nrpe_package_adminfile           = undef
           $default_nrpe_package_source              = undef
-          $default_nagios_plugins_package           = 'nagios-plugins-basic'
+          $default_nagios_plugins_package           = (versioncmp($facts[os][release][full], '20.04') < 0) ? {
+            true    => 'nagios-plugins-basic',
+            default => 'monitoring-plugins-basic',
+          }
           $default_nagios_plugins_package_adminfile = undef
           $default_nagios_plugins_package_source    = undef
           $default_nrpe_config                      = '/etc/nagios/nrpe.cfg'