toggle missing handler errors/warnings via config

(cherry picked from commit b169a61c20)

examples/ansible.cfg

@@ -70,6 +70,9 @@
 #task_includes_static = True
 #handler_includes_static = True
 
+# Controls if a missing handler for a notification event is an error or a warning
+#error_on_missing_handler = True
+
 # change this for alternative sudo implementations
 #sudo_exe = sudo
 

lib/ansible/constants.py

@@ -191,6 +191,7 @@ DEFAULT_FORCE_HANDLERS    = get_config(p, DEFAULTS, 'force_handlers', 'ANSIBLE_F
 DEFAULT_INVENTORY_IGNORE  = get_config(p, DEFAULTS, 'inventory_ignore_extensions', 'ANSIBLE_INVENTORY_IGNORE', ["~", ".orig", ".bak", ".ini", ".cfg", ".retry", ".pyc", ".pyo"], islist=True)
 DEFAULT_VAR_COMPRESSION_LEVEL = get_config(p, DEFAULTS, 'var_compression_level', 'ANSIBLE_VAR_COMPRESSION_LEVEL', 0, integer=True)
 DEFAULT_INTERNAL_POLL_INTERVAL = get_config(p, DEFAULTS, 'internal_poll_interval', None, 0.001, floating=True)
+ERROR_ON_MISSING_HANDLER  = get_config(p, DEFAULTS, 'error_on_missing_handler', 'ANSIBLE_ERROR_ON_MISSING_HANDLER', True, boolean=True)
 
 # static includes
 DEFAULT_TASK_INCLUDES_STATIC    = get_config(p, DEFAULTS, 'task_includes_static', 'ANSIBLE_TASK_INCLUDES_STATIC', False, boolean=True)

lib/ansible/plugins/strategy/__init__.py

@@ -388,6 +388,7 @@ class StrategyBase:
                             # So, per the docs, we reassign the list so the proxy picks up and
                             # notifies all other threads
                             for handler_name in result_item['_ansible_notify']:
+                                found = False
                                 # Find the handler using the above helper.  First we look up the
                                 # dependency chain of the current task (if it's from a role), otherwise
                                 # we just look through the list of handlers in the current play/all
@@ -395,15 +396,15 @@ class StrategyBase:
                                 if handler_name in self._listening_handlers:
                                     for listening_handler_name in self._listening_handlers[handler_name]:
                                         listening_handler = search_handler_blocks(listening_handler_name, iterator._play.handlers)
-                                        if listening_handler is None:
+                                        if listening_handler is not None:
-                                            raise AnsibleError("The requested handler listener '%s' was not found in any of the known handlers" % listening_handler_name)
+                                            found = True
                                         if original_host not in self._notified_handlers[listening_handler]:
                                             self._notified_handlers[listening_handler].append(original_host)
                                             display.vv("NOTIFIED HANDLER %s" % (listening_handler_name,))
-
                                 else:
                                     target_handler = search_handler_blocks(handler_name, iterator._play.handlers)
                                     if target_handler is not None:
+                                        found = True
                                         if original_host not in self._notified_handlers[target_handler]:
                                             self._notified_handlers[target_handler].append(original_host)
                                             # FIXME: should this be a callback?
@@ -411,17 +412,19 @@ class StrategyBase:
                                     else:
                                         # As there may be more than one handler with the notified name as the
                                         # parent, so we just keep track of whether or not we found one at all
-                                        found = False
                                         for target_handler in self._notified_handlers:
                                             if parent_handler_match(target_handler, handler_name):
                                                 self._notified_handlers[target_handler].append(original_host)
                                                 display.vv("NOTIFIED HANDLER %s" % (target_handler.get_name(),))
                                                 found = True
 
-                                        # and if none were found, then we raise an error
+                                # and if none were found, then we raise an error
-                                        if not found:
+                                if not found:
-                                            raise AnsibleError("The requested handler '%s' was found in neither the main handlers list nor the listening handlers list" % handler_name)
+                                  msg = "The requested handler '%s' was not found in either the main handlers list nor in the listening handlers list" % handler_name
-
+                                  if C.ERROR_ON_MISSING_HANDLER:
+                                      raise AnsibleError(msg)
+                                  else:
+                                      display.warning(msg)
 
                     if 'add_host' in result_item:
                         # this task added a new host (add_host module)