thermograph/backend/daemon/README.md

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daemon: move the Discord gateway and scheduler out of the web process into Go web/app.py started two long-lived background jobs under a leader election: the Discord gateway bot and an APScheduler. Both are stateful I/O loops -- reconnect, RESUME, heartbeat, backoff, interval timers -- living inside an async web app that also has to serve requests. This moves them into a single Go binary. Go owns ONLY the stateful I/O. It owns no climate or grading logic: anything needing data calls back into Python over a new internal-only HTTP surface (/internal/discord/grade, /internal/jobs/warm-cities, /internal/jobs/indexnow). Grading depends on polars and the parquet cache; reimplementing it in Go would make the bot's grades drift from the API's, and the slash-command path deliberately shares one grade builder so the two can never disagree. The grade route returns gateway-ready JSON -- including the ephemeral-flag drop that discord_bot.py used to do -- and Go relays those bytes verbatim without parsing the embed. Packaging: the binary is built by a golang:1.26 stage in the backend Dockerfile and shipped in the SAME image, run as a second compose service off the SAME tag. The daemon and backend share the /internal/* contract, so they must never skew versions; one image makes that structural rather than a convention. Its entrypoint bypasses entrypoint.sh -- the backend owns alembic, and two racing migrators is a real hazard. replicas: 1 in the Swarm stack is load-bearing. Discord permits exactly one gateway connection per bot token; the pin replaces core/singleton.claim_leader for this workload. update_config uses order: stop-first, since start-first would briefly run two gateways. autoscale.sh targets ${STACK_NAME}_web only, so it cannot scale this. Security: the internal routes compare the token with hmac.compare_digest and the whole router 404s when THERMOGRAPH_INTERNAL_TOKEN is unset -- fail closed, never default open. Caddy only routes /api/*, /digest and /discord/interactions to the backend, so /internal/* was never publicly reachable; the token is defence in depth. The router mounts before the catch-all frontend proxy so /internal/* cannot fall through to it. The daemon refuses to start without the token. Behaviour preserved from the Python, with the reasoning carried into the Go comments: non-privileged intents (no MESSAGE_CONTENT, so no portal review); fatal close codes 4004/4010-4014 stop rather than loop; the bot-author and self-author mention-loop guard; allowed_mentions locked to {"parse":[], "replied_user":true} so a crafted query cannot turn a reply into an @everyone ping; the first cron tick deferred one full interval rather than firing at boot, since warm-cities already runs at deploy time; and no overlapping warm-cities run, which would double-spend the archive-fetch quota. Two deliberate improvements over the Python. A close intended for RESUME now uses 4000 rather than 1000 -- Discord invalidates a session closed 1000/1001, so the Python's default close silently defeated its own resume. And MESSAGE_CREATE is handled on a bounded worker pool rather than an unbounded thread hand-off, so a flood of mentions cannot spawn unbounded work against the backend. A .dockerignore is added because a disposable backend/.venv was being swallowed by COPY . /app/ and duplicated again by the chown layer, inflating the image to 1.8 GB; it builds at 578 MB. Tests: 29 Go gateway tests covering every behaviour the deleted test_discord_bot.py asserted, plus cron/config/apiclient suites; 10 new Python tests for the internal routes (fail-closed, auth, flag drop, per-job 409 guard). Full suite 359 passed / 7 skipped; go build, vet and test -race clean.
2026-07-23 22:33:11 +00:00
# thermograph-daemon
Single Go binary that owns the backend's long-lived stateful I/O: the Discord
gateway connection (IDENTIFY/RESUME/heartbeat/reconnect backoff) and the
recurring-job timers (warm-cities, IndexNow). It replaces the two in-process
background jobs `web/app.py` used to run under leader election — one daemon
replica makes the single-connection invariant a deployment fact instead of a
runtime election.
## The Go/Python split
Go here owns **no** climate or grading logic. Grading depends on polars and the
parquet cache, and the slash-command path deliberately shares one grade builder
with the API so bot grades and API grades never drift. So anything data-shaped
is a POST back into the Python app's internal-only routes:
| Route | Purpose |
| --- | --- |
| `POST /internal/discord/grade` | `{"query": "phoenix"}` → gateway-ready Discord message JSON, relayed to Discord verbatim |
| `POST /internal/jobs/warm-cities` | trigger the warm-cities job |
| `POST /internal/jobs/indexnow` | trigger the IndexNow check-and-submit |
Every request carries `X-Thermograph-Internal-Token`. Caddy never routes
`/internal/*` to the backend, so the token is defence in depth, not the only
control. If `THERMOGRAPH_INTERNAL_TOKEN` is unset, the Python side disables the
routes and this daemon refuses to start (fail closed on both ends).
## Configuration (env)
| Var | Required | Meaning |
| --- | --- | --- |
| `THERMOGRAPH_INTERNAL_TOKEN` | yes | shared secret for the internal routes |
| `THERMOGRAPH_API_BASE_INTERNAL` | yes | backend base URL, e.g. `http://web:8137` |
| `THERMOGRAPH_DISCORD_BOT` | no | `1`/`true`/`yes`/`on` enables the gateway |
| `THERMOGRAPH_DISCORD_BOT_TOKEN` | no | bot token (gateway stays off without it) |
| `THERMOGRAPH_WARM_CITIES_INTERVAL_HOURS` | no | default 24; malformed → default |
| `THERMOGRAPH_INDEXNOW_INTERVAL_HOURS` | no | default 6; malformed → default |
## Run locally
```sh
cd backend/daemon
go build ./... && go vet ./... && go test ./...
THERMOGRAPH_INTERNAL_TOKEN=dev-token \
THERMOGRAPH_API_BASE_INTERNAL=http://localhost:8137 \
go run .
```
Deployed as `/usr/local/bin/thermograph-daemon` in the backend image.