A deployment printed four different log formats and none of them could be
joined up: uvicorn's log_config.json for the API, a hand-rolled StreamHandler in
main.py for anything not started by uvicorn, logging.basicConfig() in the worker
and in the download child (no timestamp at all), and alembic's fileConfig.
app/logs.py replaces all four with one JSON line per event (OpenTelemetry's log
data model, no SDK): ts, level, severity, source, logger, event code, message,
attributes, plus the correlation the context carries — request id, account,
download job.
Redaction is applied at the HANDLER, not at the call sites: every message, every
attribute and every traceback is scrubbed on the way out, so a secret cannot
leak by being forgotten at one of ~125 call sites. Passwords, tokens, cookies,
secret config values and email addresses never reach a line.
The access log is ours now (`http.request`): the route template instead of the
concrete path, the status, the duration and the account — and never the query
string, which uvicorn's access log printed on every single request (`?account=`,
`?source=`, the `?token=` of a share link). A well-formed client request id is
accepted and echoed in X-Request-Id, so a browser line and a server line join up.
The account comes from `request.state`, filled by the auth dependency: the
middleware is the outermost one, so it runs outside SessionMiddleware and in a
different task context.
`log_level` becomes an admin knob (sysconfig), applied without a restart and
re-applied at startup — best-effort on purpose, since a logging knob must never
be what stops the app from booting. Every compose service gets bounded json-file
logs (3×50 MB): Docker keeps every line forever by default, and the API now
writes one line per request.
Verified on the localdev stack: JSON everywhere including alembic and the
worker, the query strings gone, a supplied X-Request-Id echoed and logged, and
three /healthz hits of which only the one made while the level was DEBUG
produced a line.
Each user stores their own login cookies (Netscape cookies.txt) for an
auth-walled download host (Facebook, Instagram, X, TikTok, Reddit) in
Settings; a download of an auth-walled link on that host is retried with
the acting user's cookie.
Two load-bearing security controls, both in downloads.credentials as the
single source of truth so enqueue and the worker can't drift:
- cache privacy: a cookie-authed download salts its MediaAsset format_sig
with the user id, so the authed asset is private and never cache-served
to another user. The worker attaches a cookie ONLY when the asset it is
downloading into IS that private, salted identity.
- host scope (SEC-12): a cookie is resolved only for a URL whose netloc
the credential owns (netloc-scoped _host_is); a look-alike/unrelated
host gets none.
cookies_enc is Fernet-encrypted at rest, only decrypted in-worker into a
0600 file under staging/.auth/ (survives the retry wipe + _produced_file
scan) and unlinked in finally. The blob is never returned by a route,
logged, audited, or written to a job's error/snapshot. cookiefile is set
after the adapter's extra merge so an adapter can't clobber it. Settings
UI is write-only (host + set/updated only, never echoed). New
download_credentials table + migration 0074; per-user routes; HU+EN i18n.
Tests: host-scope, cache-privacy (no cross-user serve), encrypt-at-rest,
write-only API, worker attach-gate; FE dom test for the write-only field.
The download/edit child (yt-dlp + ffmpeg) shares one LAN box with the API,
Postgres, and Plex playback. A CPU re-encode pegged every core for ~30s and
starved web requests + playback until it finished. Full-scope S4 mitigations:
- Child self-de-prioritizes at startup (inherited by every ffmpeg/yt-dlp
descendant): CPU nice increment + best-effort idle ionice class + an
OMP_NUM_THREADS budget, all config-gated and independently disable-able.
- Cap the browser-safe re-encode's encoder threads (`-threads`) so a transcode
reserves a core for foreground work instead of claiming all of them.
- Throttle the retention GC's whole-tree orphan sweep (yield IO after each
batch of files) so its rglob can't monopolize disk IO in the API process.
- Idle-back-off the Download Center (2s→15s when nothing queued/running) and
UsageBar (2s→15s when running_jobs is 0) polls; both snap back to 2s on the
next fetch after an enqueue (invalidateDownloads refetches immediately).
Tests: encode_thread_cap (pin/reserve-core/edge), -threads flag presence,
_deprioritize (nice/ionice/OMP branches), GC sweep throttle batching.
worker.py (~1090 L) mixed the PARENT supervisor (claim + supervise + the process
loop) with the CHILD pipeline (the yt-dlp/ffmpeg download+edit that runs in the
spawned subprocess). Extract them:
worker.py 1090 -> 475 parent: claim/supervise/loop
downloads/pipeline.py (new 592) the child pipeline (_download/_process_edit +
hooks/progress/ffmpeg helpers + _Aborted)
downloads/jobdb.py (new 73) the short-lived-session helpers both sides
share (_set_job/_job_status/_touch_job/
_requeue_if_running/_reset_asset_pending +
the staging-dir paths)
The graph is one-directional (runner -> pipeline -> jobdb; worker -> jobdb; no
worker<->pipeline edge) — the parent never calls the child directly, it spawns
runner.py as a subprocess. Consumers rewired: runner import, and two tests follow
the moved symbols (_media_info/_produced_file -> pipeline; the ffmpeg-callback
patches target pipeline where the names are looked up).
Pure code motion, verbatim bodies. ruff clean, full lane 363 pass (unchanged).
Defense-in-depth after the ReDoS incident. The heavy work (yt-dlp download / ffmpeg edit)
now runs in a child process (app.downloads.runner) supervised by the worker thread, not in
the thread itself. A thread can't be killed and a C-level spin can't even be cooperatively
cancelled, so one wedged download used to pin a core, hold the GIL and freeze the whole
queue; a child process can be SIGTERM/SIGKILLed.
The supervisor kills the child (and its process group, so ffmpeg grandchildren die too)
when: a route pauses/cancels the job, it makes no progress for download_stall_timeout_seconds
(150s), it runs past download_wall_clock_max_seconds (2h), the worker is shutting down, or
the child crashes without setting state. On a kill it frees the asset and fails the job with
a retryable network error (stalls are not auto-requeued). A clean exit is left alone — the
child already wrote the terminal state, including a cooperative pause via the progress hook.
- config.py: stall / wall-clock / supervisor-poll / kill-grace settings.
- worker.py: _run_supervised + _spawn_download_child / _job_liveness / _stop_child /
_cleanup_staging; _process_job claims the asset, then hands the heavy work to the child.
- app/downloads/runner.py: the child entrypoint.
- docker-compose.localdev.yml: init:true on the worker so tini (PID 1) reaps orphaned
ffmpeg grandchildren left by a hard-kill (the worker reaps its own direct children).
- tests: watchdog decision logic + SIGTERM->SIGKILL escalation (fake proc, no real subprocess).
peter