bugsnag: emit slice_name from service_name in custom metadata tab

Observe error analytics filters on custom.slice_name to assign errors to
a slice. Store the service_name passed to setup() and write it as
custom.slice_name on every event so errors from orchestrator, api, and
metrics_poller each land in their own slice.

Consolidates all custom tab writes into a single add_tab call.

Author: morgan-wowk

cloud_pipelines_backend/instrumentation/bugsnag_instrumentation.py

@@ -35,13 +35,19 @@
 
 IS_BUGSNAG_ENABLED: bool = bool(_BUGSNAG_API_KEY)
 _setup_called: bool = False
+_service_name: str | None = None
 
 
 def _before_notify(event: bugsnag_event.Event) -> None:
     """Attach contextual logging metadata to every Bugsnag event."""
     context = contextual_logging.get_all_context_metadata()
     if context:
         event.add_tab("tangle_context", context)
+
+    custom: dict[str, str] = {}
+    if _service_name:
+        custom["slice_name"] = _service_name
+
     if _CUSTOM_GROUPING_KEY and event.original_error:
         # Use the full chain for grouping so that "LauncherError <- TimeoutError"
         # and "LauncherError <- ApiException" land in separate, stable groups.
@@ -50,7 +56,7 @@ def _before_notify(event: bugsnag_event.Event) -> None:
         )
         prefix = (event.metadata.get("extra") or {}).get("grouping_prefix")
         key_value = f"{prefix}: {chain}" if prefix else chain
-        event.add_tab("custom", {_CUSTOM_GROUPING_KEY: key_value})
+        custom[_CUSTOM_GROUPING_KEY] = key_value
         if prefix and event.errors:
             try:
                 for error in event.errors:
@@ -74,14 +80,20 @@ def _before_notify(event: bugsnag_event.Event) -> None:
                     "Could not set chain title on errorClass", exc_info=True
                 )
 
+    if custom:
+        event.add_tab("custom", custom)
+
 
 def setup(*, service_name: str | None = None) -> None:
     """Configure the Bugsnag client.
 
     No-op if TANGLE_BUGSNAG_API_KEY is not set.
 
     Args:
-        service_name: Identifies the process in Bugsnag (e.g. "tangle-api").
+        service_name: Identifies the process in Bugsnag (e.g. "tangle-orchestrator-production").
+            Also emitted as ``slice_name`` in the Bugsnag "custom" metadata tab on every event,
+            so errors can be filtered by service slice. Note: ``slice_name`` is a reserved key —
+            avoid setting ``TANGLE_BUGSNAG_CUSTOM_GROUPING_KEY=slice_name``.
     """
     if not IS_BUGSNAG_ENABLED:
         return
@@ -104,8 +116,9 @@ def setup(*, service_name: str | None = None) -> None:
             project_root=service_name,
         )
         bugsnag_sdk.before_notify(_before_notify)
-        global _setup_called
+        global _setup_called, _service_name
         _setup_called = True
+        _service_name = service_name
     except Exception:
         _logger.exception("Failed to initialize Bugsnag")
 

tests/instrumentation/test_bugsnag.py

@@ -271,6 +271,31 @@ def test_before_notify_skips_error_class_prefix_gracefully_on_bad_errors_structu
     bugsnag_module._before_notify(mock_event)
 
 
+def test_before_notify_sets_slice_name_when_service_name_configured(monkeypatch):
+    monkeypatch.setenv("TANGLE_BUGSNAG_API_KEY", "test-api-key")
+    monkeypatch.setenv("TANGLE_ENV", "staging")
+
+    import importlib
+    import cloud_pipelines_backend.instrumentation.bugsnag_instrumentation as bugsnag_module
+
+    importlib.reload(bugsnag_module)
+
+    from cloud_pipelines_backend.instrumentation import contextual_logging
+
+    contextual_logging.clear_context_metadata()
+
+    with mock.patch("bugsnag.configure"), mock.patch("bugsnag.before_notify"):
+        bugsnag_module.setup(service_name="orchestrator")
+
+    mock_event = mock.MagicMock()
+    mock_event.original_error = None
+    mock_event.metadata = {}
+
+    bugsnag_module._before_notify(mock_event)
+
+    mock_event.add_tab.assert_called_once_with("custom", {"slice_name": "orchestrator"})
+
+
 def test_before_notify_skips_empty_context(monkeypatch):
     monkeypatch.setenv("TANGLE_BUGSNAG_API_KEY", "test-api-key")
     monkeypatch.setenv("TANGLE_ENV", "staging")
@@ -287,3 +312,33 @@ def test_before_notify_skips_empty_context(monkeypatch):
     mock_event = mock.MagicMock()
     bugsnag_module._before_notify(mock_event)
     mock_event.add_tab.assert_not_called()
+
+
+def test_before_notify_omits_custom_tab_when_no_service_name_and_no_grouping_key(
+    monkeypatch,
+):
+    monkeypatch.setenv("TANGLE_BUGSNAG_API_KEY", "test-api-key")
+    monkeypatch.delenv("TANGLE_BUGSNAG_CUSTOM_GROUPING_KEY", raising=False)
+
+    import importlib
+
+    import cloud_pipelines_backend.instrumentation.bugsnag_instrumentation as bugsnag_module
+
+    importlib.reload(bugsnag_module)
+
+    from cloud_pipelines_backend.instrumentation import contextual_logging
+
+    contextual_logging.clear_context_metadata()
+
+    with mock.patch("bugsnag.configure"), mock.patch("bugsnag.before_notify"):
+        bugsnag_module.setup(service_name=None)
+
+    mock_event = mock.MagicMock()
+    mock_event.original_error = None
+    mock_event.metadata = {}
+    bugsnag_module._before_notify(mock_event)
+
+    custom_calls = [
+        c for c in mock_event.add_tab.call_args_list if c.args[0] == "custom"
+    ]
+    assert custom_calls == []