add a define to manage users in groups

manifests/groups/manage_user.pp

@@ -0,0 +1,27 @@
+define user::groups::manage_user(
+    $ensure = 'present',
+    $group,
+    $user = 'absent'
+){
+
+    if ($user != 'absent'){
+        $real_user = $user
+    } else {
+        $real_user = $name
+    }
+
+    augeas{"manage_${real_user}_in_group_${group}":
+        context => '/files/etc/group',
+    }
+    if ($ensure == 'present'){
+        Augeas["manage_${real_user}_in_group_${group}"]{
+            changes => [ "set ${group}/user[last()+1] ${real_user}" ],
+            onlyif => "match ${group}/*[../user='${real_user}'] size == 0"
+        }
+    } else {
+        Augeas["manage_${real_user}_in_group_${group}"]{
+            changes => "rm ${group}/user[.='${real_user}']",
+        }
+    }
+}
+