PTFE-1144 gcloud instances support of fixed labels (#496)

This pull request includes changes related to the configuration and
testing of custom labels for GCP instances in the runner manager
backend. The most important changes include adding a new attribute to
the `GCPInstanceConfig` class to configure custom labels, and modifying
the GCP backend test to verify the correct setting of custom labels.

runner_manager/backend/gcloud.py

@@ -149,7 +149,7 @@ def _sanitize_label_value(self, value: str) -> str:
         return value
 
     def setup_labels(self, runner: Runner) -> MutableMapping[str, str]:
-        labels: MutableMapping[str, str] = dict()
+        labels: MutableMapping[str, str] = self.instance_config.labels.copy()
         if self.manager:
             labels["runner-manager"] = self.manager
         labels["status"] = self._sanitize_label_value(runner.status)

runner_manager/models/backend.py

@@ -108,6 +108,7 @@ class GCPInstanceConfig(InstanceConfig):
     spot: bool = False
     disk_size_gb: int = 20
     disk_type: Literal["pd-ssd", "pd-standard"] = "pd-ssd"
+    labels: Dict[str, str] = {}
 
     class Config:
         arbitrary_types_allowed = True

tests/unit/backend/test_gcp.py

@@ -28,7 +28,11 @@ def gcp_group(settings, monkeypatch) -> RunnerGroup:
         backend=GCPBackend(
             name=Backends.gcloud,
             config=config,
-            instance_config=GCPInstanceConfig(),
+            instance_config=GCPInstanceConfig(
+                labels={
+                    "key": "value",
+                }
+            ),
         ),
         labels=[
             "label",
@@ -80,6 +84,7 @@ def test_gcp_setup_labels(runner: Runner, gcp_group: RunnerGroup):
     labels = gcp_group.backend.setup_labels(runner)
     assert labels["status"] == runner.status
     assert labels["busy"] == str(runner.busy).lower()
+    assert labels["key"] == "value"
 
 
 def test_gcp_spot_config(runner: Runner, gcp_group: RunnerGroup):