hermes
c0c6b4c1fc
Two follow-ups to the review of the base image change. 1. Pin the patch version: `python:3.14-slim` is a floating tag, so a rebuild could silently pick up a different base image. It is now `python:3.14.10-slim`, so a rebuild is reproducible. 2. Run the app as an unprivileged user. The app only reads its own source and talks to Mongo over the network — it writes no files — so it does not need to be root. A `beer` system user is created and the image ends with `USER beer`.
Brew Log
Stores specific-gravity data for home-brewed beer runs in Mongo and turns it into useful figures — alcohol by volume, days in the fermenter, gravity trends.
Flask app, Mongo backend, no build step for the front end.
Running it locally
python -m venv .venv
. .venv/bin/activate
pip install -r requirements-dev.txt
export MONGO_HOST=192.168.178.229
export MONGO_USER=root
export MONGO_PASS=...
export SECRET_KEY=anything-for-local-use
cd src/flask
python -m beer_data # dev server on :5000
# or, production-style:
python -m waitress --listen=0.0.0.0:5000 --call beer_data:create_app
Then open http://localhost:5000/ and sign in.
Tests
. .venv/bin/activate
python -m pytest tests/ -q
The tests use mongomock, so they need no database and no network.
Layout
src/flask/
beer_data.py entry point; exposes `app` and `create_app`
app_factory.py application factory, request-scoped Mongo repository
brewing.py pure domain logic — gravity parsing, ABV, run aggregation
views/ blueprints: auth, brews, (later) analysis
mongo/repository.py Mongo access for the beer_data and beer_runs collections
templates/ Jinja templates
static/ CSS, JS, fonts, logo (all served locally — no CDN)
tests/ pytest suite
brewing.py holds every piece of arithmetic and has no Flask or Mongo
dependency, so the maths is unit-testable on its own.
Data model
beer_data — one document per gravity reading
| Field | Type | Notes |
|---|---|---|
_id |
string | 24 random characters |
beer_run_id |
string | The run this reading belongs to, e.g. "20" |
beer_type |
string | Beer/cider name. Free text, per reading — it drifts across a run |
sg |
string | Specific gravity in points: 1039 means 1.039 |
date |
string | YYYY-MM-DD |
final_reading |
string | "True" / "False" — marks the last reading of a run |
comment |
string | Free text |
The unique key is (date, beer_run_id): re-submitting a reading for the same
run and day updates it in place rather than creating a duplicate.
A run is active while it has no reading with final_reading == "True".
beer_runs — one document per run (metadata)
Added alongside the readings to hold what cannot be derived from them: the canonical beer name, the tap number, the recorded original gravity, and brew notes. This collection is only ever inserted into, never written over by the backfill.
Alcohol by volume
Standard homebrew formula:
ABV% = (OG - FG) × 131.25
With gravity stored in points, the drop is already in points, so
ABV% = points_drop × 0.13125.
The previous version of this app used
(max - min) / 7.36 + 0.5, which is not a recognised brewing formula and overstated every result. The old figure is still computed bybrewing.legacy_abv_percent()so the history page can show the difference between the two.
For a run still in the fermenter the figure is an estimate: it uses the run's first reading as the original gravity. A run with a single reading and no recorded OG has no reliable estimate, and the UI shows a dash rather than a misleading number.
Deployment
The image is built and pushed by .gitea/workflows/build_push.yml on push to
master. See RUNBOOK.md for the cluster side.