Added option to disable default persistence

If the pelix.configadmin.persistence.default.disable property is set to
a non-empty value at framework level, the default persistence service
won't be automatically instantiated.
This is compatible with the previous behaviour.

See #113

pelix/services/__init__.py

@@ -82,6 +82,14 @@
 SERVICE_CONFIGADMIN_PERSISTENCE = "pelix.configadmin.persistence"
 """ Specification of a ConfigurationAdmin storage service """
 
+FRAMEWORK_PROP_CONFIGADMIN_DISABLE_DEFAULT_PERSISTENCE = (
+    "pelix.configadmin.persistence.default.disable"
+)
+"""
+If this framework property has a value, the default persistence service of
+ConfigurationAdmin won't be started
+"""
+
 FACTORY_CONFIGADMIN_JSON = "pelix-configadmin-persistence-json-factory"
 """ Name of the JSON ConfigurationAdmin storage component factory """
 

pelix/services/configadmin.py

@@ -993,7 +993,6 @@ def list_configurations(self, ldap_filter=None):
 @Requires("_directory", SERVICE_CONFIGADMIN_DIRECTORY)
 @Property("_conf_folder", "configuration.folder")
 @Property("_watched_folder", services.PROP_FILEINSTALL_FOLDER)
-@Instantiate("pelix-services-configuration-json-default")
 class JsonPersistence(object):
     """
     JSON configuration persistence
@@ -1201,3 +1200,33 @@ def folder_change(self, folder, added, updated, deleted):
                 except (KeyError, ValueError, IOError) as ex:
                     # Log other errors
                     _logger.error("Error updating %s: %s", pid, ex)
+
+
+@pelix.constants.BundleActivator
+class Activator(object):
+    """
+    Instantiates the default JSON configuration provider
+    """
+
+    @staticmethod
+    def start(context):
+        """
+        Bundle started
+        """
+        if context.get_property(
+            services.FRAMEWORK_PROP_CONFIGADMIN_DISABLE_DEFAULT_PERSISTENCE
+        ):
+            # No need to run the default provider
+            return
+
+        # Small trick to add a late Instantiate decoration
+        # to the component factory
+        Instantiate("pelix-services-configuration-json-default")(
+            JsonPersistence
+        )
+
+    @staticmethod
+    def stop(_):
+        """
+        Bundle stopped
+        """