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Service Bus completion events carry result-file download URLs

Date: 2026-06-17 Area: Service Bus integration (api/tasks/servicebus), examples (example/servicebus)

Motivation

An external consumer of the optional elastic-blast-completions topic could see that a job succeeded but had to enumerate the result files itself (parse result_ref.api, call the job detail, read result.files, then build each file URL) before it could download anything. The request was for the completion message to carry a ready-to-use download_url per result file so a consumer can fetch results directly.

User-facing change

A succeeded blast.transition event now includes a result_files array:

"result_files": [
  {
    "file_id": "merged_results.out.gz",
    "name": "merged_results.out.gz",
    "format": "blast_tabular",
    "size": 12345,
    "download_url": "https://<dashboard-host>/api/v1/elastic-blast/jobs/{job_id}/files/merged_results.out.gz"
  }
]

download_url points at the dashboard's authenticated file-streaming gateway (GET /api/v1/elastic-blast/jobs/{job_id}/files/{file_id}), which the api sidecar proxies to the sibling OpenAPI plane. A consumer downloads by calling it with a bearer token. It is never a Storage SAS URL or a direct blob URL (charter §9). When the dashboard public base cannot be resolved, the file metadata is still emitted but download_url is omitted, so a subscriber can fall back to result_ref.

The field is present only on succeeded events when the optional completion topic is configured; queued / running / failed events are unchanged. The addition does not alter the event_id dedup digest.

API / IaC diff summary

  • api/tasks/servicebus/tasks.py
  • new _result_files_for_event(job, openapi_job_id) — builds the per-file metadata + download_url from the sibling job detail (_external_result_files) and the resolved dashboard public base (resolve_control_plane_url). Capped at _MAX_RESULT_FILES (25).
  • _transition_event(...) gains an optional result_files parameter, emitted only when supplied.
  • _publish_one_bridge(...) attaches result_files on the succeeded transition (best-effort: a build failure logs and emits an empty list).
  • No IaC change. No new env var. Uses the existing CONTAINER_APP_NAME + CONTAINER_APP_ENV_DNS_SUFFIX (or DASHBOARD_PUBLIC_URL / operator setting) that resolve_control_plane_url already reads.
  • example/servicebus/consume.py — --source completions --download now reads result_files, acquires a bearer token (ELB_BEARER_TOKEN or az account get-access-token --resource $ELB_API_CLIENT_ID), and downloads each download_url to --download-dir.

Validation

  • uv run pytest -q api/tests/test_servicebus_tasks.py — 35 passed (includes the new test_result_files_for_event_*, test_transition_event_includes_result_files_*, and test_publish_transitions_succeeded_attaches_download_urls).
  • uv run ruff check api/tasks/servicebus/tasks.py api/tests/test_servicebus_tasks.py example/servicebus — clean.
  • example/servicebus/consume.py --self-test — green (asserts plan_downloads turns the event's result_files into download targets and that the URL is the dashboard gateway, not a SAS URL).
  • Live end-to-end against ca-elb-dashboard + elb-cluster-01: send a real Service Bus request → drain → OpenAPI submit → BLAST run → succeeded completion event carrying download_url → consumer downloads the result file.