Parts Inventory

A catalog of what's actually on the shelf — components, filament, fasteners, tooling — so "do I have one of those?" is a five-second search instead of an hour of opening drawers.

Runs as a FastAPI + SQLite container on mainserver (192.168.50.8) behind Caddy at https://parts.tjm77.com, alongside the other ~/srv services.

The data model

One parts table holds what every kind of stock has in common — name, quantity, unit, location, cost, min-stock threshold. Everything type-specific lives in part_specs as key/value rows, so a 0603 resistor, a spool of PLA and a box of M3 screws share a table without a schema fork.

Categories and locations are both nestable trees. Workshop / Bin A3 is a real path, and filtering by Workshop returns everything in every bin beneath it. Sidebar counts roll up the same way, so they always match what clicking the filter actually returns.

Each category carries a spec template — the properties worth recording for that kind of thing. Pick "Filament" on the add form and it pre-fills Material, Colour, Diameter, Brand, Print Temp, and switches the unit to grams. That's what keeps manual entry from being a blank page. Templates are suggestions only: delete any row, add your own, ignore them entirely.

Every quantity change is written to stock_log, so a part's history answers "where did those 40 headers go" instead of just showing a smaller number than you remembered.

Search is SQLite FTS5 over name, description, manufacturer, MPN, spec values, tags, category and location, with prefix matching so results narrow as you type. Typing 1.75mm, prusament, 0603 or Bin A3 all find the right things.

Running it locally

python3 -m venv .venv && .venv/bin/pip install -r requirements.txt
PARTS_AUTH=off PARTS_DB=$PWD/data/parts.db .venv/bin/uvicorn app.main:app --port 8123

Then open http://127.0.0.1:8123.

Tests

.venv/bin/python -m tests.test_api          # 166 checks, in-process
.venv/bin/python -m tests.test_concurrency  # 15 checks, against a real uvicorn

test_api exercises the API end to end against a throwaway database — the auth gate and session-token signing, nested categories and locations, search across every indexed field, filter rollups, stock adjustment and history, patch semantics including explicit nulls, taxonomy cycle rejection, security headers and asset versioning, login throttling, and the full password-management flow including scrypt hashing, session invalidation and the recovery CLI.

test_concurrency needs a real server process, because a lost update only shows up when two requests genuinely overlap inside SQLite. It fires overlapping adjustments, patches and creates at one part and asserts the stock log always sums to the stored quantity, and races taxonomy renames against reads to check the search index never describes a name the tree no longer has.

Configuration

The password is managed from the app, not from a config file. PARTS_PASSWORD is only the bootstrap credential: it works until a password is set through the UI, and is ignored from then on (otherwise "changing" the password would leave the old one working). The stored password is a salted scrypt hash in the settings table, which lives in the /data volume and survives rebuilds.

Variable	Meaning
PARTS_PASSWORD	Bootstrap password, used only until one is set in the app.
PARTS_SECRET	Signing key for the session cookie. openssl rand -hex 32.
PARTS_SESSION_DAYS	Session lifetime, default 30.
PARTS_AUTH	off disables the login gate (LAN-only use).
PARTS_DB	SQLite path. /data/parts.db in the container.
PARTS_LOGIN_MAX_FAILURES	Failed logins allowed per window, default 10.
PARTS_LOGIN_WINDOW	Throttle window in seconds, default 300.
PARTS_SECURE_COOKIE	auto (default) trusts X-Forwarded-Proto; on/off force it.

Every token carries a session epoch. Changing the password bumps it, which invalidates every outstanding cookie at once while re-issuing one for the browser that made the change — so a password change really does sign out other devices, with no need to touch PARTS_SECRET on the host. Sign out other devices in Settings bumps the epoch on its own.

Failed logins are throttled on a global window rather than per source address. Caddy appends to X-Forwarded-For instead of replacing it, so the client-supplied end of that header is forgeable and a per-IP bucket would be trivially evaded. There is one legitimate user, so a global cap costs nothing real; the trade-off is that a guessing spray can block the login form for the window. Existing sessions keep working throughout.

Deploying

Lives at /home/jay/srv/parts/ on .8 and follows the same conventions as the other services there — build: ., external caddy_web network, named volume for /data.

~/srv/parts is a checkout of this repository, so deploying is a pull:

ssh jay@192.168.50.8
cd ~/srv/parts && git pull && docker compose up -d --build

.env is untracked and gitignored, so it survives the pull. ~/srv (the infra repo) ignores parts/, since this directory is its own repository.

The database is in the parts_parts_data docker volume, which survives rebuilds.

Back it up with SQLite's backup API, not cp. The database runs in WAL mode, so recently committed rows may still live in parts.db-wal and copying parts.db alone can silently lose them. VACUUM INTO takes a consistent snapshot of a live database:

docker exec parts python -c \
  "import sqlite3; sqlite3.connect('/data/parts.db').execute(\"VACUUM INTO '/data/backup.db'\")"
docker cp parts:/data/backup.db ./parts-backup-$(date +%F).db
docker exec parts rm /data/backup.db

Restore by stopping the container, copying the file back over /data/parts.db and deleting any leftover -wal/-shm alongside it.

API

Everything under /api is JSON and cookie-authenticated. GET /healthz is open.

GET    /api/parts?q=&category_id=&location_id=&tag=&low_stock=&sort=&limit=&offset=
POST   /api/parts
GET    /api/parts/{id}
PATCH  /api/parts/{id}
DELETE /api/parts/{id}
POST   /api/parts/{id}/adjust      {delta, reason}
GET    /api/parts/{id}/history
GET    /api/categories   POST /api/categories   PATCH|DELETE /api/categories/{id}
GET    /api/locations    POST /api/locations    PATCH|DELETE /api/locations/{id}
GET    /api/tags
GET    /api/stats

The "what could I build with what I'm holding?" idea is meant to arrive as another consumer of these endpoints — the arbiter on .8 already has the lane routing and typed-action machinery for it — rather than as a fork of them.

Passwords

Open Settings (the gear in the header) and use the Password section. It asks for the current password, takes a new one twice, and signs out every other device. Until a password has been set in the app, a banner says so.

The only reason to touch a terminal is a forgotten password:

docker exec -it parts python -m app.admin set-password    # prompts, twice
docker exec parts python -m app.admin show-status         # where the password comes from
docker exec parts python -m app.admin clear-password      # fall back to PARTS_PASSWORD

Each of those signs out every session too.

Hardening notes

Responses carry X-Content-Type-Options, X-Frame-Options, Referrer-Policy and a Content-Security-Policy that keeps the page to same-origin scripts and no framing; HSTS is added when X-Forwarded-Proto says the original request was HTTPS. The session cookie is HttpOnly, SameSite=Lax and Secure, and its signature is a fixed-width HMAC appended to the payload rather than delimited — a delimiter byte can occur inside a raw digest, which previously invalidated about 12% of issued tokens.

Static assets are served under content-hashed URLs (app.js?v=<sha>), so Cloudflare caching them for hours is harmless: a deploy changes the URL. The bare, unhashed paths are served no-cache so nothing can pin stale frontend code against a newer API.