From 25f76e1044f45af0ca105cd7e98d3c6de2ccbf95 Mon Sep 17 00:00:00 2001
From: Jvst Me <git@jvst.me>
Date: Fri, 14 Aug 2026 14:21:28 +0200
Subject: [PATCH] Fix server compatibility with 0.20.[27-29] clients

Ignore `GatewayConfiguration.router` in client
requests if `null`, which is what 0.20.27,
0.20.28, and 0.20.29 clients send by default.
---
 src/dstack/_internal/core/models/common.py    | 19 ++++++++++
 .../_internal/server/schemas/gateways.py      | 20 ++++++++--
 .../_internal/core/models/test_common.py      | 38 ++++++++++++++++++-
 3 files changed, 73 insertions(+), 4 deletions(-)

diff --git a/src/dstack/_internal/core/models/common.py b/src/dstack/_internal/core/models/common.py
index 69e4297dca..a649420edb 100644
--- a/src/dstack/_internal/core/models/common.py
+++ b/src/dstack/_internal/core/models/common.py
@@ -57,6 +57,25 @@ class FrozenCoreModel(CoreModel):
     model_config = ConfigDict(frozen=True)
 
 
+def pop_null_field(values: Any, *path: str) -> Any:
+    """
+    Drop a field at `path` from the `values` nested dict if it's set to `null`.
+
+    Mutates and returns the same `values` object.
+    """
+    if not isinstance(values, dict):
+        return values
+    node = values
+    for key in path[:-1]:
+        node = node.get(key)
+        if not isinstance(node, dict):
+            return values
+    field = path[-1]
+    if field in node and node[field] is None:
+        del node[field]
+    return values
+
+
 T = TypeVar("T")
 
 _type_adapters: dict[Any, TypeAdapter] = {}
diff --git a/src/dstack/_internal/server/schemas/gateways.py b/src/dstack/_internal/server/schemas/gateways.py
index 3c13ba6ae6..fa1e82ab89 100644
--- a/src/dstack/_internal/server/schemas/gateways.py
+++ b/src/dstack/_internal/server/schemas/gateways.py
@@ -1,8 +1,8 @@
-from typing import Annotated, List, Optional
+from typing import Annotated, Any, List, Optional
 
-from pydantic import Field
+from pydantic import Field, model_validator
 
-from dstack._internal.core.models.common import CoreModel
+from dstack._internal.core.models.common import CoreModel, pop_null_field
 from dstack._internal.core.models.gateways import (
     ApplyGatewayPlanInput,
     GatewayConfiguration,
@@ -25,6 +25,12 @@ class GetGatewayRequest(CoreModel):
 class GetGatewayPlanRequest(CoreModel):
     spec: GatewaySpec
 
+    @model_validator(mode="before")
+    @classmethod
+    def _drop_null_router(cls, values: Any) -> Any:
+        # Compatibility with 0.20.27, 0.20.28, 0.20.29 clients
+        return pop_null_field(values, "spec", "configuration", "router")
+
 
 class ApplyGatewayPlanRequest(CoreModel):
     plan: ApplyGatewayPlanInput
@@ -35,6 +41,14 @@ class ApplyGatewayPlanRequest(CoreModel):
         ),
     ]
 
+    @model_validator(mode="before")
+    @classmethod
+    def _drop_null_router(cls, values: Any) -> Any:
+        # Compatibility with 0.20.27, 0.20.28, 0.20.29 clients
+        values = pop_null_field(values, "plan", "spec", "configuration", "router")
+        values = pop_null_field(values, "plan", "current_resource", "configuration", "router")
+        return values
+
 
 class DeleteGatewaysRequest(CoreModel):
     names: List[str]
diff --git a/src/tests/_internal/core/models/test_common.py b/src/tests/_internal/core/models/test_common.py
index 8cc1e50032..60dd34616a 100644
--- a/src/tests/_internal/core/models/test_common.py
+++ b/src/tests/_internal/core/models/test_common.py
@@ -1,6 +1,6 @@
 import pytest
 
-from dstack._internal.core.models.common import EntityReference
+from dstack._internal.core.models.common import EntityReference, pop_null_field
 
 
 class TestEntityReferenceParse:
@@ -25,3 +25,39 @@ def test_valid(self, value, expected):
     def test_invalid(self, value: str):
         with pytest.raises(ValueError, match="Invalid entity reference"):
             EntityReference.parse(value)
+
+
+class TestPopNullField:
+    def test_drops_null_field_at_top_level(self):
+        values = {"router": None, "backend": "aws"}
+        assert pop_null_field(values, "router") == {"backend": "aws"}
+
+    def test_drops_null_field_in_nested_dict(self):
+        values = {"spec": {"configuration": {"router": None, "backend": "aws"}}}
+        assert pop_null_field(values, "spec", "configuration", "router") == {
+            "spec": {"configuration": {"backend": "aws"}}
+        }
+
+    def test_leaves_non_null_field_untouched(self):
+        values = {"configuration": {"router": "some-router"}}
+        assert pop_null_field(values, "configuration", "router") == {
+            "configuration": {"router": "some-router"}
+        }
+
+    def test_field_absent(self):
+        values = {"configuration": {"backend": "aws"}}
+        assert pop_null_field(values, "configuration", "router") == {
+            "configuration": {"backend": "aws"}
+        }
+
+    def test_intermediate_path_missing(self):
+        values = {"backend": "aws"}
+        assert pop_null_field(values, "configuration", "router") == {"backend": "aws"}
+
+    def test_intermediate_path_not_a_dict(self):
+        values = {"configuration": None}
+        assert pop_null_field(values, "configuration", "router") == {"configuration": None}
+
+    def test_top_level_not_a_dict(self):
+        values = "not-a-dict"
+        assert pop_null_field(values, "configuration", "router") == "not-a-dict"