rbd: More strictly validate rbd_ceph_conf

The rbd_ceph_conf parameter accepts a valid path for *.conf file,
because of the internal logic to detect the cluster name.

Change-Id: Ia42f5db1ff701b5ba90dbdb7e80c7b906b406222

manifests/backend/rbd.pp

@@ -121,7 +121,7 @@ define cinder::backend::rbd (
   $backend_availability_zone         = $facts['os_service_default'],
   $reserved_percentage               = $facts['os_service_default'],
   $max_over_subscription_ratio       = $facts['os_service_default'],
-  $rbd_ceph_conf                     = '/etc/ceph/ceph.conf',
+  Cinder::CephConf $rbd_ceph_conf    = '/etc/ceph/ceph.conf',
   $rbd_flatten_volume_from_snapshot  = $facts['os_service_default'],
   $rbd_secret_uuid                   = $facts['os_service_default'],
   $rbd_max_clone_depth               = $facts['os_service_default'],

spec/type_aliases/cephconf_spec.rb

@@ -0,0 +1,35 @@
+require 'spec_helper'
+
+describe 'Cinder::CephConf' do
+  describe 'valid types' do
+    context 'with valid types' do
+      [
+        '/etc/ceph/ceph.conf',
+        '/etc/ceph.conf',
+        '/ceph.conf',
+        '/etc/ceph/foo/ceph.conf',
+        '/etc/ceph/foo.conf',
+      ].each do |value|
+        describe value.inspect do
+          it { is_expected.to allow_value(value) }
+        end
+      end
+    end
+  end
+
+  describe 'invalid types' do
+    context 'with garbage inputs' do
+      [
+        'etc/ceph/ceph.conf',
+        'ceph.conf',
+        '/etc/ceph/ceph.config',
+        '/etc/ceph/ceph',
+        '<SERVICE DEFAULT>',
+      ].each do |value|
+        describe value.inspect do
+          it { is_expected.not_to allow_value(value) }
+        end
+      end
+    end
+  end
+end

types/cephconf.pp

@@ -0,0 +1 @@
+type Cinder::CephConf = Pattern[/^\/([^\n\/\0]+\/*)*[^\n\/\0]+\.conf$/]