bug(tools): experiment_only_ingest_path and experiment_run_grafana_demo pass stale prometheus_url= to controller_service.start()

[milindsrivastava1997]

Bug

experiment_only_ingest_path.py and experiment_run_grafana_demo.py both call controller_service.start() with a stale prometheus_url=prometheus_url keyword argument and are missing the required discovery_backend parameter.

PR #396 refactored misc.py's ControllerService.start() to replace prometheus_url: Optional[str] with discovery_backend: DiscoveryBackend (a required parameter with no default). It updated experiment_run_clickhouse.py and experiment_run_e2e.py, but left these two scripts behind.

Effect

• prometheus_url=prometheus_url silently disappears into **kwargs — the Prometheus URL is never used.
• discovery_backend is missing entirely → TypeError: start() missing 1 required positional argument: 'discovery_backend' at runtime.

Broken call sites

experiment_only_ingest_path.py (~line 298):

controller_service.start(
    controller_input_file=controller_input_config,
    streaming_engine=args.streaming_engine,
    controller_remote_output_dir=CONTROLLER_REMOTE_OUTPUT_DIR,
    punting=args.controller_punting,
    prometheus_url=prometheus_url,   # stale kwarg, silently dropped
    # discovery_backend=...          # required, missing
)

experiment_run_grafana_demo.py (~line 351):

controller_service.start(
    controller_input_file=controller_input_config,
    streaming_engine=args.streaming_engine,
    controller_remote_output_dir=CONTROLLER_REMOTE_OUTPUT_DIR,
    punting=args.controller_punting,
    prometheus_url=prometheus_url,   # stale kwarg, silently dropped
    # discovery_backend=...          # required, missing
)

Fix

Replace prometheus_url=prometheus_url with:

discovery_backend=DiscoveryBackend(
    type="prometheus",
    url=prometheus_url,
    database=None,
),

Matching the pattern already used in experiment_run_e2e.py.

Root cause

Introduced in #396 — misc.py was updated but these two scripts were not.