Correctly validate 'apps.misp.api.*' config settings

CHANGELOG.md

@@ -16,6 +16,9 @@ Every entry has a category for which we use the following visual abbreviations:
   address some limitations in the configuration framework.
   [#157](https://github.com/tenzir/threatbus/pull/157)
 
+- 🐞 Fixed config validation for the 'apps.misp.api' setting.
+  [#161](https://github.com/tenzir/threatbus/pull/161)
+
 ## [2021.07.29]
 
 - 🐞 Threatbus now only attempts to load plugins that are explicitly

config.yaml.example

@@ -42,7 +42,7 @@ plugins:
       module_namespace: Tenzir
     # Requires the 'threatbus-misp' package to be installed
     misp:
-      api:                       # Optional
+      api:                       # Optional. If present, all of 'host', 'ssl', 'key' are required.
         host: https://localhost
         ssl: false
         key: MISP_API_KEY

plugins/apps/threatbus_misp/threatbus_misp/plugin.py

@@ -228,10 +228,16 @@ def config_validators() -> List[Validator]:
             is_type_of=list,
             default=[],
         ),
+        # TODO: Allow default values for 'host' and 'ssl'.
         Validator(
-            f"plugins.apps.{plugin_name}.api",
-            is_type_of=dict,
-            default={},
+            f"plugins.apps.{plugin_name}.api.host",
+            f"plugins.apps.{plugin_name}.api.ssl",
+            f"plugins.apps.{plugin_name}.api.key",
+            when=Validator(f"plugins.apps.{plugin_name}.api", must_exist=True),
+            required=True,
+            messages={
+                "must_exist_true": "All of 'api.host', 'api.ssl', and 'api.key' must be defined when the 'api' key exists"
+            },
         ),
         zmq_kafka_mut_exclusive_validator,
         zmq_validator,