[Bugfix] Redact api_key in startup logs and compile cache factors

[Andy365-365]

What

The API server startup log prints all non-default arguments verbatim:

INFO ... [api_utils.py:273] non-default args: {'model_tag': 'org/model', 'api_key': '***', ...}

So --api-key / VLLM_API_KEY lands in plain text in container and host
logs. Anyone with log read access (docker logs, host filesystem, log
shippers) recovers the API key from a single startup line.

A second leak: compile_factors() starts from every registered VLLM_*
env var, and the raw factor dict is persisted on disk in
cache_key_factors.json (compiled-artifacts cache metadata). Since
VLLM_API_KEY was not excluded, the key was also written in plaintext to
that file — and it additionally invalidated the compile cache on every key
rotation.

This PR:

• redacts the api_key value to *** in the startup log, keeping the
  field name so operators can still tell a key was configured
• excludes VLLM_API_KEY from compile_factors() so it is neither hashed
  into the cache key nor persisted in cache_key_factors.json

Only the logging path and the factor list are touched;
get_non_default_args() and the --args-json handoff to the Rust frontend
are unchanged (the frontend stores keys as hashes).

Why this is not duplicating an existing PR

Searched open PRs/issues for api_key redact, api_key mask, api_key leak in title/body: no open PR or issue addresses this log line.

Test commands run and results

ruff check vllm/entrypoints/serve/utils/api_utils.py   # All checks passed
ruff format --check vllm/entrypoints/serve/utils/api_utils.py  # already formatted
pytest tests/entrypoints/serve/utils/test_api_utils.py -v
14 passed (11 pre-existing + 3 new redaction tests)

AI-assisted

This PR was developed with AI assistance (Claude). The change is small
and self-contained; please flag if the approach looks off.

---

The API key was only ever logged, never sent anywhere — so the leak is
free real estate for anyone reading logs. I've fixed mine by rotating;
you're on your own.

[claude]

Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

[github-actions]

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[DarkLight1337]

Thanks

[DarkLight1337]

/ci run

[github-actions]

✅ Triggered Buildkite CI #84122 for commit 0e10bd3246fa.

[mergify]

Hi @Andy365-365, the pre-commit checks have failed. Please run:

uv pip install pre-commit>=4.5.1
pre-commit install
pre-commit run --all-files

Then, commit the changes and push to your branch.

For future commits, pre-commit will run automatically on changed files before each commit.

[DarkLight1337]

/ci run

[github-actions]

✅ Triggered Buildkite CI #84169 for commit 1e09803b7f91.

[Andy365-365]

/ci retry

[github-actions]

✅ Queued 1 failed job(s) for retry in Buildkite CI #84169.

[vrdn-23]

Also probably need to fix this in the rust backend and as a completeness measure, make sure it is in the IGNORE_LIST in vllm/envs.py, so that it doesn't get written to the disk for the compile cache.
cc @DarkLight1337

[Andy365-365]

Also probably need to fix this in the rust backend and as a completeness measure, make sure it is in the IGNORE_LIST in vllm/envs.py, so that it doesn't get written to the disk for the compile cache. cc @DarkLight1337

Done - VLLM_API_KEY is now excluded from compile_factors() so it won't be persisted in cache_key_factors.json (see latest commit, with a regression test).

For the Rust backend, the api_keys field already uses a redacted Debug impl (rust/src/server/src/config.rs, fmt_redacted_api_keys, asserted in cli/tests.rs as api_keys: [; 2]), so I believe that side is already covered. Let me know if you were pointing at a different code path.

[Andy365-365]

/ci run

[github-actions]

✅ Triggered Buildkite CI #84313 for commit 565b89a3f5df.

[Andy365-365]

/ci run

[github-actions]

✅ Triggered Buildkite CI #84557 for commit 00ed9b556ae8.