Abolfazlrwm opened a new pull request, #76627:
URL: https://github.com/apache/airflow/pull/76627
closes: #55432
## Problem
Extra operator links are currently resolved through XCom for every task
instance, regardless of whether the URL actually depends on the run. A link
whose URL is constant (docs, dashboards, consoles) still requires the task to
push an XCom entry in `finalize()`, and the API server to read it back.
Consequences:
- a link that was never pushed renders empty - e.g. for failed or
still-running task instances (reported in #55432);
- every task execution pays an XCom write per link even when the URL is a
constant.
## Root cause
The serialized DAG encodes extra links only as `{link_name: xcom_key}`
(`_serialize_operator_extra_links`), and the API server always deserializes
them into `XComOperatorLink`, whose `get_link()` reads the URL from XCom. There
is no place in the serialization format for a run-independent URL.
This is why PR #70343 (which introduced the Task-SDK-only `static_url`
override and skipped the XCom push) was closed: without a serialization change,
skipping the push makes the link render empty in the UI. I rebuilt the approach
on top of that feedback - happy to adjust further.
## Fix
1. **task-sdk** - `BaseOperatorLink` gains an optional `static_url` property
(defaults to `None`); `get_link()` falls back to it, so subclasses with a
constant URL no longer need to implement `get_link()`. `finalize()` skips the
XCom push for links that declare `static_url`.
2. **serialization** - static links are encoded as `{link_name:
{"static_url": ...}}` (dynamic links keep `{link_name: xcom_key}`);
deserialization produces a new `StaticOperatorLink` that returns the stored URL
without touching XCom. Old blobs (plain string entries) keep deserializing
exactly as before.
3. **SERIALIZER_VERSION 3 -> 4** - so readers older than this change reject
new blobs loudly instead of misreading static entries as XCom keys;
`dag_version_diff`'s supported set and canonicalization chain follow the bump,
and the TS SDK version pin is updated.
The UI needs no change: the links endpoint resolves links via
`SerializedBaseOperator.get_extra_links()`, which now returns the constant URL
directly.
## Tests
- task-sdk: `test_task_run_with_static_operator_extra_link` and
`test_finalize_with_mixed_operator_extra_links` assert that static links are
not pushed to XCom while dynamic links still are (the gap that sank #70343).
- core: `test_static_operator_link_returns_url_without_xcom` and
`test_static_operator_extra_link_roundtrip` (encode + decode + render without
XCom).
- API: `test_should_respond_200_static_link_without_xcom` renders the link
through `GET /dags/{dag_id}/dagRuns/{run_id}/taskInstances/{task_id}/links`
with zero XCom rows - the UI-rendering requirement from #70343's closing review.
All affected test files pass locally (Python 3.11, SQLite):
`test_task_runner.py` 595 passed, `test_dag_serialization.py` 263 passed,
`test_dag_version_diff.py` 565 passed, `test_extra_links.py` 29 passed, plus
`test_operatorlink.py` and `test_ts_sdk_serialization_version.py`. `pre-commit
run --files` passes for ruff/ruff-format on the changed files; several
repo-local script hooks (rich/yaml/astor importers, exec-bit checks) fail in my
sandbox on untouched files as well, so I could not run them here - CI will
cover them.
## Docs
New "Static operator extra links" section in
`airflow-core/docs/howto/define-extra-link.rst`.
---
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