Support gateway: true in service configurations

Allow setting `gateway: true` in service
configurations, which will enforce that the
service runs on the default gateway or is rejected
if one isn't available.

**Compatibility**: pre-0.20.1 clients will not be
able to list (`dstack ps`), get, or update
(`dstack apply`) services that were created by
0.20.1+ clients with the `gateway: true` property.

Author: jvstme

src/dstack/_internal/core/models/configurations.py

@@ -725,7 +725,8 @@ class ServiceConfigurationParams(CoreModel):
         Field(
             description=(
                 "The name of the gateway. Specify boolean `false` to run without a gateway."
-                " Omit to run with the default gateway"
+                " Specify boolean `true` to run with the default gateway."
+                " Omit to run with the default gateway if there is one, or without a gateway otherwise"
             ),
         ),
     ] = None
@@ -795,16 +796,6 @@ def convert_replicas(cls, v: Range[int]) -> Range[int]:
             raise ValueError("The minimum number of replicas must be greater than or equal to 0")
         return v
 
-    @validator("gateway")
-    def validate_gateway(
-        cls, v: Optional[Union[bool, str]]
-    ) -> Optional[Union[Literal[False], str]]:
-        if v == True:
-            raise ValueError(
-                "The `gateway` property must be a string or boolean `false`, not boolean `true`"
-            )
-        return v
-
     @root_validator()
     def validate_scaling(cls, values):
         scaling = values.get("scaling")

src/dstack/_internal/server/services/services/__init__.py

@@ -55,6 +55,10 @@ async def register_service(session: AsyncSession, run_model: RunModel, run_spec:
         gateway = await get_project_default_gateway_model(
             session=session, project=run_model.project
         )
+        if gateway is None and run_spec.configuration.gateway == True:
+            raise ResourceNotExistsError(
+                "The service requires a gateway, but there is no default gateway in the project"
+            )
 
     if gateway is not None:
         service_spec = await _register_service_in_gateway(session, run_model, run_spec, gateway)

src/tests/_internal/server/routers/test_runs.py

@@ -2013,6 +2013,13 @@ def mock_gateway_connections(self) -> Generator[None, None, None]:
                 "https://gateway.default-gateway.example",
                 id="submits-to-default-gateway",
             ),
+            pytest.param(
+                [("default-gateway", True), ("non-default-gateway", False)],
+                True,
+                "https://test-service.default-gateway.example",
+                "https://gateway.default-gateway.example",
+                id="submits-to-default-gateway-when-gateway-true",
+            ),
             pytest.param(
                 [("default-gateway", True), ("non-default-gateway", False)],
                 "non-default-gateway",
@@ -2108,7 +2115,7 @@ async def test_return_error_if_specified_gateway_not_exists(
         }
 
     @pytest.mark.asyncio
-    async def test_return_error_if_specified_gateway_is_true(
+    async def test_return_error_if_specified_gateway_is_true_and_no_gateway_exists(
         self, test_db, session: AsyncSession, client: AsyncClient
     ) -> None:
         user = await create_user(session=session, global_role=GlobalRole.USER)
@@ -2123,5 +2130,12 @@ async def test_return_error_if_specified_gateway_is_true(
             headers=get_auth_headers(user.token),
             json={"run_spec": run_spec},
         )
-        assert response.status_code == 422
-        assert "must be a string or boolean `false`, not boolean `true`" in response.text
+        assert response.status_code == 400
+        assert response.json() == {
+            "detail": [
+                {
+                    "msg": "The service requires a gateway, but there is no default gateway in the project",
+                    "code": "resource_not_exists",
+                }
+            ]
+        }