btcprice/README.md

# btcprice

Bitcoin price tracker UI. Serves an HTML page with live price updates streamed from
[btcdata](../btcdata), which this server proxies over WebSocket and renders as HTML fragments
for HTMX.

## Quick Start

```bash
# Start btcdata first (provides price data)
cd ../btcdata && make run

# Local dev — creates .venv and installs requirements on first run
make run       # starts on port 4000
make tailwind  # watch Tailwind CSS (separate terminal)
```

Optionally `cp .env.example .env` to override `BTCDATA_URL`; without it the code default
(`http://localhost:4100`) applies. `make run-local` requires a `.env` defining
`BTCDATA_LOCAL_URL`.

Run the test suite with `make test`. Test-only packages are kept in `requirements-dev.txt` and are
not installed in the production image.

## Docker

`docker compose up -d` starts **btcprice only** — it does not bring up btcdata. Both compose
files attach to the external `btc-network`, so create it once and start btcdata separately:

```bash
docker network create btc-network      # once
cd ../btcdata && docker compose up -d
cd ../btcprice && docker compose up -d
```

| Service  | Local dev      | Docker                                |
|----------|----------------|---------------------------------------|
| btcprice | localhost:4000 | localhost:4041 (container port 4040)  |
| btcdata  | localhost:4100 | localhost:4102                        |

Inside `btc-network`, btcprice reaches btcdata as `http://btcdata:4102`.

## CI images

Pushes to the `main` branch and tags matching `v*` run
`.gitea/workflows/build.yml`. The workflow tests the application and publishes linux/amd64 images
to `harbor.pmagnus.cloud/btcprice/btcprice`. Branch builds receive an immutable
`main-<UTC timestamp>` tag (for Flux selection) and a SHA-qualified companion tag; release tags
receive the version without `v` and a SHA-qualified companion tag. The image embeds the short Git
SHA, available from `/api/version`.

The workflow requires the repository secrets `HARBOR_ROBOT_USER` and `HARBOR_ROBOT_TOKEN`. It only
pushes images and intentionally has no Kubernetes credentials.

## Production deployment

Production is GitOps-managed at **https://btcprice.k8s.pmagnus.cloud**:

```text
git push → Gitea Actions on anvil → Harbor → Flux → k3s → ingress-nginx → Traefik TLS
```

Flux image automation commits the newest approved `main-<UTC timestamp>` image to the separate
`magnus/deploy` repository. The manifests are in `../deploy/apps/btcprice`, and two replicas run with
one pod on each k3s node. CI never receives cluster credentials. Do not deploy production with
Docker Compose or manual `kubectl apply`; rollback by reverting the immutable image change in the
GitOps repository.

btcdata remains an external dependency running on citadel. Kubernetes represents it with a
selectorless Service and EndpointSlice, so pods use `http://btcdata:4102` without embedding its IP in
the Deployment.

## Legacy deployment (citadel)

```bash
./deploy-citadel.sh
```

Same method as `../elprice/deploy-citadel.sh`: builds the image locally for the target's
architecture (citadel is x86_64 → `linux/amd64`), copies `docker-compose.citadel.yml` and
`.env.citadel` to `/home/pmp/apps/btcprice` on the host as `docker-compose.yml` / `.env`,
pipes the image over SSH with `docker save | docker load`, and runs
`docker compose up -d --no-build`. No registry involved.

The temporary migration fallback listens on **http://192.168.50.195:4041** and proxies to the
btcdata running on citadel as well. It is retained only for the validation/rollback window; the
Kubernetes hostname is the production endpoint. Both attach to the external `btc-network` there, so `BTCDATA_URL` is
`http://btcdata:4102` (set in `.env.citadel`) — the service name inside the network, not a LAN
address. The deploy script creates `btc-network` on the host if it does not exist yet.

Overridable: `BTCPRICE_DEPLOY_HOST`, `BTCPRICE_DEPLOY_DIR`, `BTCPRICE_IMAGE_NAME`,
`BTCPRICE_PLATFORM`, `BTCPRICE_NETWORK`.

## Environment Variables

| Variable | Default | Description |
|---|---|---|
| `BTCDATA_URL` | `http://localhost:4100` | btcdata service URL the server proxies to |
| `APP_VERSION` | `development` | Build identifier returned by `/api/version` |
| `BTCDATA_LOCAL_URL` | — | Used by `make run-local` instead of `BTCDATA_URL` |
| `DOCKER_BTCDATA_PORT` | `4102` | btcdata's port inside `btc-network` (local compose only) |
| `BTCPRICE_PORT` | `4041` | Host port in the citadel deployment (`.env.citadel`) |

The HTTP port is not configurable via environment: `make run` hardcodes 4000 and the Docker
image's `CMD` hardcodes 4040.

## Health endpoints

- `/api/health` is a process-only liveness check and remains healthy during a btcdata outage.
- `/api/ready` checks `${BTCDATA_URL}/api/health` with a three-second timeout and returns 503 when
  btcdata is unavailable.
- `/api/version` returns the build SHA embedded by CI.

## How It Works

The browser loads a page with HTMX and the WebSocket extension, which connects back to
**btcprice** at `/ws/price` and `/ws/strike` — the browser never contacts btcdata directly.

Each of those endpoints opens an upstream WebSocket to btcdata (`/api/price/ws` and
`/api/strike/ws`), converts each JSON message to an HTML fragment (`price_json_to_html`,
`strike_json_to_html`), and forwards it to the browser. HTMX swaps the received
`<div id="price-display">` / `<div id="strike-display">` into the DOM. Price changes are
color-coded (green up, red down). Reconnection is handled by HTMX.

## Tech Stack

Python · FastAPI · Uvicorn · websockets · HTMX · Tailwind CSS v4

The Clojure implementation this replaced is on the `clojure` branch.

The 24-hour chart uses 48 half-hour candles from rustbtcdata’s
`/api/kraken-half-hour` endpoint, aggregated from minute OHLC data. It refreshes
every five minutes and includes the current partial half-hour candle.