nilsandClaude Opus 5.5
d5f68e1bd9
Modelled on the OAuth device authorization grant (RFC 8628) and on
only when APPROVAL_PASSWORD is set (at least 12 characters):
- POST /v1/pair/start opens a request for an installation and returns
a short user code and the /pair URL for the car's QR code;
POST /v1/pair/poll returns pending, the car's own token (once),
denied or expired. Requests live 10 minutes, in memory.
- GET/POST /pair is a script-free approval page for the phone
(strict CSP, no framing). Five wrong passwords lock approvals for a
minute.
- Each car gets its own 43-character token; only its SHA-256 is stored
(measurement "device"), and the device is persisted before the car
can collect the token. Tokens are loaded at startup, so a restart
keeps paired cars working; the server refuses to start if they cannot
be loaded.
- GET /v1/devices and POST /v1/devices/{id}/revoke, authenticated with
the approval password, list and revoke cars.
- The shared INGEST_TOKEN keeps working.
31 tests (race detector clean), govulncheck clean. Tested end to end
against InfluxDB 2.7.12: pairing, wrong password, single collection,
persistence across restarts, revocation (also across a restart), and
that InfluxDB holds only the hash.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QLJfZQZeAKAwSqViTmLzki
103 lines
4.3 KiB
Markdown
103 lines
4.3 KiB
Markdown
# Nils' MG4 — car server
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A small Go service at car.stinnesbeck.com: the API the car writes to, and the ABRP
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forwarder. Data lives in InfluxDB 2; Grafana reads it from there for the dashboards
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(`../k8s/grafana/`).
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```
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car ──live telemetry───▶ server ──▶ ABRP api.iternio.com/1/tlm/send
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──daily chunks─────▶ │
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──charging sessions▶ ▼
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InfluxDB 2 ◀── Grafana
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```
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## Configuration
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Environment only; the server refuses to start when a required value is missing.
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| Name | Notes |
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| `INFLUX_URL`, `INFLUX_TOKEN`, `INFLUX_ORG` | required; the token needs read/write on the bucket |
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| `INFLUX_BUCKET` | default `mg4` |
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| `INGEST_TOKEN` | required, at least 24 characters: `openssl rand -hex 32` |
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| `ABRP_API_KEY`, `ABRP_USER_TOKEN` | optional; both needed to forward |
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| `ABRP_MIN_INTERVAL_SECONDS` | default 5 |
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| `APPROVAL_PASSWORD` | optional, at least 12 characters; switches pairing on (see below) |
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| `PUBLIC_URL` | the address a phone uses, for the pairing QR code; derived from the request if empty |
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| `LISTEN_ADDR` | default `:8080` |
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The ABRP credentials never reach the car.
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## Endpoints
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The ingest endpoints accept `Authorization: Bearer <token>` with either the shared `INGEST_TOKEN`
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or a paired car's own token.
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- `POST /v1/telemetry` — `{ installationId, samples: [...] }`, up to 500 samples in ABRP's `tlm`
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field names and units (`utc` in epoch seconds; flags as 0/1 or booleans). Unknown fields are
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dropped, known ones bounded. Stored, then the newest sample is forwarded to ABRP if it is under
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5 minutes old.
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- `PUT /v1/consumption/daily` — one delta chunk of a day's consumption.
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- `PUT /v1/charging-sessions/{sessionId}` — a finished DC session with its curve.
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- `GET /v1/consumption/history/{installationId}` — the car reads its own totals back.
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- `GET /v1/health` — `{"status":"ok"}`.
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A bad request is a 400 naming the field; a database failure is a 500 without detail.
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## Pairing a car by QR code
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So nobody types a token in the car. Modelled on the OAuth device authorization grant (RFC 8628);
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on only when `APPROVAL_PASSWORD` is set.
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1. The car calls `POST /v1/pair/start` `{installationId}` and shows the returned
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`verificationUriComplete` as a QR code, plus the short `userCode` (e.g. `K7F-3QX`).
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2. The phone opens `/pair?code=…`, the owner checks the code and approves with the approval
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password. Five wrong passwords lock approvals for a minute.
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3. The car polls `POST /v1/pair/poll` `{deviceCode}`: 202 pending, 200 with its own token
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(handed out once), 403 denied, 410 expired (after 10 minutes) or unknown.
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Each car gets its own 43-character token; only its SHA-256 is stored (measurement `device` in
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the same bucket), and the device is persisted before the car can collect the token, so a
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restart never loses a paired car. Manage cars with the approval password:
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```sh
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curl -H "Authorization: Bearer $APPROVAL_PASSWORD" https://car.stinnesbeck.com/v1/devices
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curl -X POST -H "Authorization: Bearer $APPROVAL_PASSWORD" https://car.stinnesbeck.com/v1/devices/<id>/revoke
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```
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## Storage
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One bucket, `installationId` tag on every point:
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| Measurement | Timestamp | Tags | Fields |
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| `telemetry` | sample `utc` | — | the ABRP fields that were sent |
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| `consumption_chunk` | `recordedAt` | `date` | km, kwh, hours, socDrop, sohPercent |
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| `charging_session` | `startedAt` | `sessionId` | endedAtMs, duration, energy, cost, start/end SOC |
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| `charging_curve` | point time | `sessionId` | powerKw, socPercent |
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| `device` | paired at | `deviceId` | tokenHash, installationId, revoked |
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A point with the same measurement, tags and timestamp replaces the earlier one, so the car's
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retries are idempotent: a cached chunk is re-sent with its original `recordedAt`. Days and the
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lifetime total are summed from the chunks when read. Numbers are always written as floats,
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because InfluxDB fixes a field's type on first write.
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## Development
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```sh
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nix develop # from the repository root: Go, govulncheck, InfluxDB 2
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cd server
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go test ./...
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govulncheck ./...
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```
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## Container image
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```sh
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podman build -t git.stinnesbeck.com/nils/mg4-server:<version> .
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podman push git.stinnesbeck.com/nils/mg4-server:<version>
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```
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The build runs `go vet` and the tests. The image is a static binary on distroless (about
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11 MB), running as UID 65532 on port 8080.
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