Feature: brownout deprecated API features via enable_brownout flag

mwdb/core/config.py

@@ -136,6 +136,7 @@ class MWDBConfig(Config):
     log_only_slow_sql = key(cast=intbool, required=False, default=False)
     use_x_forwarded_for = key(cast=intbool, required=False, default=False)
     enable_debug_log = key(cast=intbool, required=False, default=False)
+    enable_brownout = key(cast=intbool, required=False, default=False)
 
 
 @section("karton")

mwdb/core/deprecated.py

@@ -6,7 +6,9 @@
 from typing import Optional
 
 from flask import g, request
+from werkzeug.exceptions import BadRequest
 
+from mwdb.core.config import app_config
 from mwdb.core.log import getLogger
 from mwdb.core.metrics import metric_deprecated_usage
 
@@ -60,6 +62,14 @@ def uses_deprecated_api(
         f"Used deprecated feature: {feature}"
         + (f" ({method} {endpoint})" if endpoint is not None else "")
     )
+    if app_config.mwdb.enable_brownout:
+        if feature == DeprecatedFeature.legacy_api_key_v2:
+            # This feature won't be removed in v3
+            return
+        raise BadRequest(
+            f"Brownout: {feature} API feature is deprecated and currently disabled. "
+            f"Please upgrade your MWDB API client."
+        )
 
 
 def deprecated_endpoint(feature: DeprecatedFeature):