fixes Yakifo/amqtt#51 : plugins which fail to import or load should stop the broker from starting

amqtt/broker.py

@@ -145,6 +145,9 @@ class Broker:
         loop: asyncio loop. defaults to `asyncio.get_event_loop()`.
         plugin_namespace: plugin namespace to use when loading plugin entry_points. defaults to `amqtt.broker.plugins`.
 
+    Raises:
+        BrokerError, ParserError, PluginError
+
     """
 
     states: ClassVar[list[str]] = [

amqtt/client.py

@@ -88,6 +88,9 @@ class MQTTClient:
             it will be generated randomly by `amqtt.utils.gen_client_id`
         config: dictionary of configuration options (see [client configuration](client_config.md)).
 
+    Raises:
+        PluginError
+
     """
 
     def __init__(self, client_id: str | None = None, config: dict[str, Any] | None = None) -> None:
@@ -142,7 +145,7 @@ class MQTTClient:
             [CONNACK](http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Toc398718033)'s return code
 
         Raises:
-            amqtt.client.ConnectException: if connection fails
+            ClientError, ConnectError
 
         """
         additional_headers = additional_headers if additional_headers is not None else {}

amqtt/errors.py

@@ -1,3 +1,6 @@
+from typing import Any
+
+
 class AMQTTError(Exception):
     """aMQTT base exception."""
 
@@ -18,6 +21,20 @@ class BrokerError(Exception):
     """Exceptions thrown by broker."""
 
 
+class PluginError(Exception):
+    """Exceptions thrown when loading or initializing a plugin."""
+
+
+class PluginImportError(PluginError):
+    def __init__(self, plugin: Any) -> None:
+        super().__init__(f"Plugin import failed: {plugin!r}")
+
+
+class PluginInitError(PluginError):
+    def __init__(self, plugin: Any) -> None:
+        super().__init__(f"Plugin init failed: {plugin!r}")
+
+
 class ClientError(Exception):
     """Exceptions thrown by client."""
 

amqtt/plugins/manager.py

@@ -8,6 +8,8 @@ from importlib.metadata import EntryPoint, EntryPoints, entry_points
 import logging
 from typing import Any, NamedTuple
 
+from amqtt.errors import PluginImportError, PluginInitError
+
 _LOGGER = logging.getLogger(__name__)
 
 
@@ -80,17 +82,21 @@ class PluginManager:
         try:
             self.logger.debug(f" Loading plugin {ep!s}")
             plugin = ep.load()
-            self.logger.debug(f" Initializing plugin {ep!s}")
 
-            plugin_context = copy.copy(self.app_context)
-            plugin_context.logger = self.logger.getChild(ep.name)
+        except ImportError as e:
+            self.logger.debug(f"Plugin import failed: {ep!r}", exc_info=True)
+            raise PluginImportError(ep) from e
+
+        self.logger.debug(f" Initializing plugin {ep!s}")
+
+        plugin_context = copy.copy(self.app_context)
+        plugin_context.logger = self.logger.getChild(ep.name)
+        try:
             obj = plugin(plugin_context)
             return Plugin(ep.name, ep, obj)
-        except ImportError:
-            self.logger.warning(f"Plugin {ep!r} import failed")
-            self.logger.debug("", exc_info=True)
-
-        return None
+        except Exception as e:
+            self.logger.debug(f"Plugin init failed: {ep!r}", exc_info=True)
+            raise PluginInitError(ep) from e
 
     def get_plugin(self, name: str) -> Plugin | None:
         """Get a plugin by its name from the plugins loaded for the current namespace.

amqtt/scripts/broker_script.py

@@ -7,7 +7,7 @@ from yaml.parser import ParserError
 
 from amqtt import __version__ as amqtt_version
 from amqtt.broker import Broker
-from amqtt.errors import BrokerError
+from amqtt.errors import BrokerError, PluginError
 from amqtt.utils import read_yaml_config
 
 logger = logging.getLogger(__name__)
@@ -58,7 +58,7 @@ def broker_main(
     loop = asyncio.get_event_loop()
     try:
         broker = Broker(config)
-    except (BrokerError, ParserError) as exc:
+    except (BrokerError, ParserError, PluginError) as exc:
         typer.echo(f"❌ Broker failed to start: {exc}", err=True)
         raise typer.Exit(code=1) from exc
 

pyproject.toml

@@ -185,7 +185,7 @@ timeout = 10
 asyncio_default_fixture_loop_scope = "function"
 #addopts = ["--tb=short", "--capture=tee-sys"]
 #log_cli = true
-#log_level = "DEBUG"
+log_level = "DEBUG"
 
 # ------------------------------------ MYPY ------------------------------------
 [tool.mypy]

tests/plugins/mock_plugins.py

@@ -0,0 +1,10 @@
+from amqtt.broker import BrokerContext
+from amqtt.plugins.base import BasePlugin
+
+# intentional import error to test broker response
+from pathlib import Pat  # noqa
+
+class MockImportErrorPlugin(BasePlugin):
+
+    def __init__(self, context: BrokerContext) -> None:
+        super().__init__(context)

tests/plugins/test_plugins.py

@@ -1,12 +1,17 @@
 import inspect
+from importlib.metadata import EntryPoint
 from logging import getLogger
 from pathlib import Path
 from types import ModuleType
 from typing import Any
+from unittest.mock import patch
 
 import pytest
 
 import amqtt.plugins
+from amqtt.broker import Broker, BrokerContext
+from amqtt.errors import PluginError, PluginInitError, PluginImportError
+from amqtt.plugins.base import BasePlugin
 from amqtt.plugins.manager import BaseContext
 
 _INVALID_METHOD: str = "invalid_foo"
@@ -61,3 +66,62 @@ def test_plugins_correct_has_attr() -> None:
         __import__(name)
 
     _verify_module(module, module.__name__)
+
+
+class MockInitErrorPlugin(BasePlugin):
+
+    def __init__(self, context: BrokerContext) -> None:
+        super().__init__(context)
+        raise KeyError
+
+
+@pytest.mark.asyncio
+async def test_plugin_exception_while_init() -> None:
+    class MockEntryPoints:
+
+        def select(self, group) -> list[EntryPoint]:
+            match group:
+                case 'tests.mock_plugins':
+                    return [
+                            EntryPoint(name='TestExceptionPlugin', group='tests.mock_plugins', value='tests.plugins.test_plugins:MockInitErrorPlugin'),
+                        ]
+                case _:
+                    return list()
+
+    with patch("amqtt.plugins.manager.entry_points", side_effect=MockEntryPoints) as mocked_mqtt_publish:
+
+        config = {
+            "listeners": {
+                "default": {"type": "tcp", "bind": "127.0.0.1:1883", "max_connections": 10},
+            },
+            'sys_interval': 1
+        }
+
+        with pytest.raises(PluginInitError):
+            _ = Broker(plugin_namespace='tests.mock_plugins', config=config)
+
+
+@pytest.mark.asyncio
+async def test_plugin_exception_while_loading() -> None:
+    class MockEntryPoints:
+
+        def select(self, group) -> list[EntryPoint]:
+            match group:
+                case 'tests.mock_plugins':
+                    return [
+                            EntryPoint(name='TestExceptionPlugin', group='tests.mock_plugins', value='tests.plugins.mock_plugins:MockImportErrorPlugin'),
+                        ]
+                case _:
+                    return list()
+
+    with patch("amqtt.plugins.manager.entry_points", side_effect=MockEntryPoints) as mocked_mqtt_publish:
+
+        config = {
+            "listeners": {
+                "default": {"type": "tcp", "bind": "127.0.0.1:1883", "max_connections": 10},
+            },
+            'sys_interval': 1
+        }
+
+        with pytest.raises(PluginImportError):
+            _ = Broker(plugin_namespace='tests.mock_plugins', config=config)