Add configuration option for entityID.

Sets the entityID in the service provider metadata file.
If not provided, entityID is autogenerated.

Change-Id: I75fc734661575e809f92aea17b75530001b2db73

src/config.yaml

@@ -5,6 +5,13 @@ options:
     description: |
       Protocol name to use for URL and generation. Must match the one that
       will be configured via OS-FEDERATION API.
+  entity-id-url:
+    type: string
+    default:
+    description: |
+      Optional field to provide the entity ID to be used in the service
+      provider metadata. If set to default (""), entity ID is generated
+      automatically.
   idp-name:
     type: string
     default: 'myidp'

src/lib/charm/openstack/keystone_saml_mellon.py

@@ -131,6 +131,15 @@ class KeystoneSAMLMellonConfigurationAdapter(
     def supported_nameid_formats(self):
         return self.nameid_formats.split(',')
 
+    @property
+    def entity_id(self):
+        if self.entity_id_url is None:
+            # Generate entity ID automatically
+            return '{}{}'.format(self.keystone_fid_service_provider.base_url,
+                                 self.sp_auth_path)
+        else:
+            return self.entity_id_url
+
     IDP_METADATA_INVALID = ('idp-metadata resource is not a well-formed'
                             ' xml file')
     IDP_METADATA_URL_ERROR = ('an error has occurred during idp-metadata-url'

src/templates/mellon-sp-metadata.xml

@@ -1,5 +1,5 @@
 <EntityDescriptor
-	entityID="{{ keystone_fid_service_provider.base_url }}{{ options.sp_auth_path }}"
+	entityID="{{ options.entity_id }}"
 	xmlns="urn:oasis:names:tc:SAML:2.0:metadata"
 	xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
 	<SPSSODescriptor