feat(BA-4631): Add update_deployment_policy GQL mutation

Add Strawberry GraphQL mutation for updating deployment policies,
internally using the existing upsert mechanism.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jopemachine

src/ai/backend/manager/api/gql/deployment/__init__.py

@@ -40,6 +40,8 @@
     routes,
     sync_replicas,
     update_auto_scaling_rule,
+    # Policy
+    update_deployment_policy,
     update_model_deployment,
     update_route_traffic_status,
 )
@@ -144,6 +146,9 @@
     UpdateAutoScalingRulePayload,
     UpdateDeploymentInput,
     UpdateDeploymentPayload,
+    # Policy (mutation types)
+    UpdateDeploymentPolicyInputGQL,
+    UpdateDeploymentPolicyPayloadGQL,
     UpdateRouteTrafficStatusInputGQL,
     UpdateRouteTrafficStatusPayloadGQL,
     get_route_pagination_spec,
@@ -204,6 +209,8 @@
     "DeploymentStrategyTypeGQL",
     "RollingUpdateConfigInputGQL",
     "RollingUpdateStrategySpecGQL",
+    "UpdateDeploymentPolicyInputGQL",
+    "UpdateDeploymentPolicyPayloadGQL",
     # Replica Types
     "ActivenessStatus",
     "LivenessStatus",
@@ -267,6 +274,8 @@
     "deployments",
     "sync_replicas",
     "update_model_deployment",
+    # Resolvers - Policy
+    "update_deployment_policy",
     # Resolvers - Replica
     "replica",
     "replica_status_changed",

src/ai/backend/manager/api/gql/deployment/resolver/__init__.py

@@ -21,6 +21,9 @@
     sync_replicas,
     update_model_deployment,
 )
+from .policy import (
+    update_deployment_policy,
+)
 from .replica import (
     replica,
     replica_status_changed,
@@ -55,6 +58,8 @@
     "delete_model_deployment",
     "sync_replicas",
     "deployment_status_changed",
+    # Policy
+    "update_deployment_policy",
     # Replica
     "replicas",
     "replica",

src/ai/backend/manager/api/gql/deployment/resolver/policy.py

@@ -0,0 +1,38 @@
+"""Deployment policy resolver functions."""
+
+from __future__ import annotations
+
+from uuid import UUID
+
+import strawberry
+from strawberry import Info
+
+from ai.backend.manager.api.gql.deployment.types.policy import (
+    DeploymentPolicyGQL,
+    UpdateDeploymentPolicyInputGQL,
+    UpdateDeploymentPolicyPayloadGQL,
+)
+from ai.backend.manager.api.gql.types import StrawberryGQLContext
+from ai.backend.manager.services.deployment.actions.deployment_policy.upsert_deployment_policy import (
+    UpsertDeploymentPolicyAction,
+)
+
+
+@strawberry.mutation(description="Added in 26.4.0")  # type: ignore[misc]
+async def update_deployment_policy(
+    input: UpdateDeploymentPolicyInputGQL,
+    info: Info[StrawberryGQLContext],
+) -> UpdateDeploymentPolicyPayloadGQL:
+    """Update (upsert) a deployment policy for a deployment."""
+    deployment_uuid = UUID(str(input.deployment_id))
+    upserter = input.to_upserter(deployment_uuid)
+
+    processor = info.context.processors.deployment
+    result = await processor.upsert_deployment_policy.wait_for_complete(
+        UpsertDeploymentPolicyAction(upserter=upserter)
+    )
+
+    return UpdateDeploymentPolicyPayloadGQL(
+        deployment_policy=DeploymentPolicyGQL.from_data(result.data),
+        created=result.created,
+    )

src/ai/backend/manager/api/gql/deployment/types/__init__.py

@@ -57,6 +57,8 @@
     DeploymentStrategyTypeGQL,
     RollingUpdateConfigInputGQL,
     RollingUpdateStrategySpecGQL,
+    UpdateDeploymentPolicyInputGQL,
+    UpdateDeploymentPolicyPayloadGQL,
 )
 from .replica import (
     ActivenessStatus,
@@ -166,6 +168,8 @@
     "DeploymentStrategyTypeGQL",
     "RollingUpdateConfigInputGQL",
     "RollingUpdateStrategySpecGQL",
+    "UpdateDeploymentPolicyInputGQL",
+    "UpdateDeploymentPolicyPayloadGQL",
     # Replica
     "ActivenessStatus",
     "LivenessStatus",

src/ai/backend/manager/api/gql/deployment/types/policy.py

@@ -4,13 +4,15 @@
 
 from datetime import datetime
 from typing import Self
+from uuid import UUID
 
 import strawberry
 from strawberry import ID
 from strawberry.relay import Node, NodeID
 
 from ai.backend.common.data.model_deployment.types import DeploymentStrategy
 from ai.backend.manager.data.deployment.types import DeploymentPolicyData
+from ai.backend.manager.data.deployment.upserter import DeploymentPolicyUpserter
 from ai.backend.manager.errors.deployment import InvalidDeploymentStrategySpec
 from ai.backend.manager.models.deployment_policy import BlueGreenSpec, RollingUpdateSpec
 
@@ -129,3 +131,54 @@ def to_spec(self) -> BlueGreenSpec:
             auto_promote=self.auto_promote,
             promote_delay_seconds=self.promote_delay_seconds,
         )
+
+
+# ========== Mutation Input/Payload Types ==========
+
+
+@strawberry.input(
+    name="UpdateDeploymentPolicyInput",
+    description="Added in 26.3.0. Input for updating a deployment policy. Internally upserts the policy.",
+)
+class UpdateDeploymentPolicyInputGQL:
+    deployment_id: ID
+    strategy: DeploymentStrategyTypeGQL
+    rollback_on_failure: bool = False
+    rolling_update: RollingUpdateConfigInputGQL | None = None
+    blue_green: BlueGreenConfigInputGQL | None = None
+
+    def to_upserter(self, deployment_uuid: UUID) -> DeploymentPolicyUpserter:
+        """Convert to DeploymentPolicyUpserter for the service layer."""
+        from ai.backend.manager.errors.api import InvalidAPIParameters
+
+        strategy = DeploymentStrategy(self.strategy.value)
+        strategy_spec: RollingUpdateSpec | BlueGreenSpec
+        match strategy:
+            case DeploymentStrategy.ROLLING:
+                if self.rolling_update is None:
+                    strategy_spec = RollingUpdateSpec(max_surge=1, max_unavailable=0)
+                else:
+                    strategy_spec = self.rolling_update.to_spec()
+            case DeploymentStrategy.BLUE_GREEN:
+                if self.blue_green is None:
+                    strategy_spec = BlueGreenSpec(auto_promote=False, promote_delay_seconds=0)
+                else:
+                    strategy_spec = self.blue_green.to_spec()
+            case _:
+                raise InvalidAPIParameters(f"Unsupported deployment strategy: {strategy}")
+
+        return DeploymentPolicyUpserter(
+            deployment_id=deployment_uuid,
+            strategy=strategy,
+            strategy_spec=strategy_spec,
+            rollback_on_failure=self.rollback_on_failure,
+        )
+
+
+@strawberry.type(
+    name="UpdateDeploymentPolicyPayload",
+    description="Added in 26.3.0. Result of updating a deployment policy.",
+)
+class UpdateDeploymentPolicyPayloadGQL:
+    deployment_policy: DeploymentPolicyGQL
+    created: bool

src/ai/backend/manager/api/gql/schema.py

@@ -76,6 +76,7 @@
     routes,
     sync_replicas,
     update_auto_scaling_rule,
+    update_deployment_policy,
     update_model_deployment,
     update_route_traffic_status,
 )
@@ -429,6 +430,7 @@ class Mutation:
     delete_model_deployment = delete_model_deployment
     sync_replicas = sync_replicas
     add_model_revision = add_model_revision
+    update_deployment_policy = update_deployment_policy
     # Notification - Admin APIs
     admin_create_notification_channel = admin_create_notification_channel
     admin_update_notification_channel = admin_update_notification_channel