snapshot of https://github.com/makeplane/plane.git @ d868349a55de79979eb8b98701bf1702c67ad634 (2026-09-15)

apps/api/plane/utils/core/dbrouters.py

@@ -0,0 +1,75 @@
+# Copyright (c) 2023-present Plane Software, Inc. and contributors
+# SPDX-License-Identifier: AGPL-3.0-only
+# See the LICENSE file for details.
+
+"""
+Database router for read replica selection.
+This router determines which database to use for read/write operations
+based on the request context set by the ReadReplicaRoutingMiddleware.
+"""
+
+import logging
+from typing import Type
+
+from django.db import models
+
+from .request_scope import should_use_read_replica
+
+logger = logging.getLogger("plane.db")
+
+
+class ReadReplicaRouter:
+    """
+    Database router that directs read operations to replica when appropriate.
+    This router works in conjunction with ReadReplicaRoutingMiddleware to:
+    - Route read operations to replica database when request context allows
+    - Always route write operations to primary database
+    - Ensure migrations only run on primary database
+    """
+
+    def db_for_read(self, model: Type[models.Model], **hints) -> str:
+        """
+        Determine which database to use for read operations.
+        Args:
+            model: The Django model class being queried
+            **hints: Additional routing hints
+        Returns:
+            str: Database alias ('replica' or 'default')
+        """
+        if should_use_read_replica():
+            logger.debug(f"Routing read for {model._meta.label} to replica database")
+            return "replica"
+        else:
+            logger.debug(f"Routing read for {model._meta.label} to primary database")
+            return "default"
+
+    def db_for_write(self, model: Type[models.Model], **hints) -> str:
+        """
+        Determine which database to use for write operations.
+        All write operations always go to the primary database to ensure
+        data consistency and avoid replication lag issues.
+        Args:
+            model: The Django model class being written to
+            **hints: Additional routing hints
+        Returns:
+            str: Always returns 'default' (primary database)
+        """
+        logger.debug(f"Routing write for {model._meta.label} to primary database")
+        return "default"
+
+    def allow_migrate(self, db: str, app_label: str, model_name: str = None, **hints) -> bool:
+        """
+        Ensure migrations only run on the primary database.
+        Args:
+            db: Database alias
+            app_label: Application label
+            model_name: Model name (optional)
+            **hints: Additional routing hints
+        Returns:
+            bool: True if migration is allowed on this database
+        """
+        # Only allow migrations on the primary database
+        allowed = db == "default"
+        if not allowed:
+            logger.debug(f"Blocking migration for {app_label} on {db} database")
+        return allowed