Allow additional domains to be add later

This commit adds support for expansion of an already existing
certificate by checking if every in Puppet configured domain is present
in the certificate on the filesystem.

Fixes voxpupuliGH-94.

manifests/certonly.pp

@@ -52,9 +52,9 @@
   }
 
   if ($custom_plugin) {
-    $command_start = "${letsencrypt_command} --text --agree-tos --non-interactive certonly "
+    $command_start = "${letsencrypt_command} --text --agree-tos --non-interactive --expand certonly "
   } else {
-    $command_start = "${letsencrypt_command} --text --agree-tos --non-interactive certonly -a ${plugin} "
+    $command_start = "${letsencrypt_command} --text --agree-tos --non-interactive --expand certonly -a ${plugin} "
   }
 
   if $plugin == 'webroot' {
@@ -82,11 +82,12 @@
   $live_path = "${config_dir}/live/${domains[0]}/cert.pem"
 
   $execution_environment = [ "VENV_PATH=${letsencrypt::venv_path}", ] + $environment
+  $verify_domains = join($domains, ' -d ')
   exec { "letsencrypt certonly ${title}":
     command     => $command,
     path        => $::path,
     environment => $execution_environment,
-    creates     => $live_path,
+    unless      => [ "test -f ${live_path}", "${letsencrypt_command} certificates -d ${verify_domains}"],
     require     => Class['letsencrypt'],
   }