Add an audit unregister option

Allow users to remove audit scripts through a simple CLI call. The
unregister-audit call will remove an audit script from audit.cfg,
thus stopping the execution of all but the currently scheduled audit
scripts.

partially implements blueprint simple api
Change-Id: I1d5328d87b607c2f5cfdaebb7448a11673f38d48

entropy/__main__.py

@@ -60,6 +60,15 @@ def _add_to_list(engine, script_type, script_name, **script_args):
         return False
 
 
+def _remove_from_list(engine, script_type, script_name):
+    backend = _get_backend_from_engine(engine)
+    try:
+        backend.remove_script(script_type, script_name)
+    except Exception:
+        LOG.exception("Could not remove %s script %s",
+                      script_type, script_name)
+
+
 def register_audit(args):
     LOG.info('Registering audit script %s', args.name)
 
@@ -74,6 +83,14 @@ def register_audit(args):
         LOG.info('Registered audit %s', args.name)
 
 
+def unregister_audit(args):
+    LOG.info('Unregistering audit script %s', args.name)
+    if not args.name and args.engine:
+        LOG.error('Need a audit name and engine to unregister')
+        return
+    _remove_from_list(args.engine, 'audit', args.name)
+
+
 def register_repair(args):
     LOG.info('Registering repair script %s', args.name)
 
@@ -151,6 +168,14 @@ def parse():
                                        help='Engine')
     register_audit_parser.set_defaults(func=register_audit)
 
+    unregister_audit_parser =\
+        subparsers.add_parser('unregister-audit',
+                              help='Unregister a repair script')
+    unregister_audit_parser.add_argument('-n', dest='name', action='store',
+                                         help='Repair script name')
+    unregister_audit_parser.add_argument('-e', dest='engine', action='store',
+                                         help='Engine')
+    unregister_audit_parser.set_defaults(func=unregister_audit)
     register_repair_parser =\
         subparsers.add_parser('register-repair',
                               help='Register a repair script')

entropy/backends/base.py

@@ -67,3 +67,7 @@ class Backend(object):
     @abc.abstractmethod
     def add_script(self, script_type, data):
         pass
+
+    @abc.abstractmethod
+    def remove_script(self, script_type, script_name):
+        pass

entropy/backends/file_backend.py

@@ -69,3 +69,21 @@ class FileBackend(base.Backend):
     def add_script(self, script_type, data):
         script_metadata = self.get_script_cfg(script_type)
         utils.write_yaml(data, script_metadata)
+
+    @staticmethod
+    def remove_script_from_cfg(metadata, name):
+        scripts = utils.load_yaml(metadata)
+        try:
+            scripts.pop(name)
+        except KeyError:
+            raise
+        return scripts
+
+    def remove_script(self, script_type, script_name):
+        try:
+            script_metadata = self.get_script_cfg(script_type)
+            final_data = FileBackend.remove_script_from_cfg(script_metadata,
+                                                            script_name)
+            utils.write_yaml(final_data, script_metadata, append=False)
+        except Exception:
+            raise