Check plugin settings

documentation/dev/plugins.rst

@@ -150,12 +150,28 @@ This will find `css/styles.css` if you add that folder and file to your Blueprin
 .. note:: This styling will only apply to the pages defined in your plugin (to pages based on your own base template). To apply a styling to all other pages which are served by FlexMeasures, consider using the config setting :ref:`extra-css-config`. 
 
 
-Adding config options
+Adding config settings
 ^^^^^^^^^^^^^^^^^^^^^^^^
 
-You might want to override some FlexMEasures configuration settings from within your plugin. Some examples for possible settings are named on this page, e.g. the custom style (see above) or custom logo (see below). There is a `record_once` function on Blueprints which can help with this. Example:
+FlexMeasures can be made to check for any custom config settings your plugin is using.
+Required and optional config options can be registered by setting the ``__settings__`` attribute on your plugin module:
 
-.. code-block: python
+.. code-block:: python
+
+    __settings__ = {
+        "required": (
+            "MY_PLUGIN_SETTING_A",
+            "MY_PLUGIN_SETTING_B",
+        ),
+        "optional": (
+            "MY_PLUGIN_SETTING_C",
+            "MY_PLUGIN_SETTING_D",
+        ),
+    }
+
+You might want to override some FlexMeasures configuration settings from within your plugin. Some examples for possible settings are named on this page, e.g. the custom style (see above) or custom logo (see below). There is a `record_once` function on Blueprints which can help with this. Example:
+
+.. code-block:: python
 
     @our_client_bp.record_once
     def record_logo_path(setup_state):

flexmeasures/utils/app_utils.py

@@ -2,6 +2,7 @@
 import os
 import sys
 import importlib.util
+import warnings
 from importlib.abc import Loader
 
 import click
@@ -16,6 +17,14 @@
 from flexmeasures.app import create as create_app
 
 
+class ConfigurationWarning(Warning):
+    pass
+
+
+class ConfigurationError(ValueError):
+    pass
+
+
 @click.group(cls=FlaskGroup, create_app=create_app)
 @with_appcontext
 def flexmeasures_cli():
@@ -246,6 +255,8 @@ def register_plugins(app: Flask):
             continue
 
         plugin_version = getattr(module, "__version__", "0.1")
+        plugin_settings = getattr(module, "__settings__", {})
+        check_config_settings(app, plugin_settings)
 
         # Look for blueprints in the plugin's main __init__ module and register them
         plugin_blueprints = [
@@ -265,3 +276,26 @@ def register_plugins(app: Flask):
         app.config["LOADED_PLUGINS"][plugin_name] = plugin_version
     app.logger.info(f"Loaded plugins: {app.config['LOADED_PLUGINS']}")
     sentry_sdk.set_context("plugins", app.config.get("LOADED_PLUGINS", {}))
+
+
+def check_config_settings(app, settings: dict):
+    """Make sure expected config settings exist."""
+    missing_optional_config_settings = []
+    if "optional" in settings:
+        for setting in settings["optional"]:
+            if app.config.get(setting) is None:
+                missing_optional_config_settings.append(setting)
+        if missing_optional_config_settings:
+            warnings.warn(
+                f"Missing optional config setting(s): {missing_optional_config_settings}",
+                category=ConfigurationWarning,
+            )
+    if "required" in settings:
+        missing_required_config_settings = []
+        for setting in settings["required"]:
+            if app.config.get(setting) is None:
+                missing_required_config_settings.append(setting)
+        if missing_required_config_settings:
+            raise ConfigurationError(
+                f"Missing required config setting(s): {missing_required_config_settings}"
+            )