netwatch-server is an MIT-licensed Go HTTP backend by
[@sneak](https://sneak.berlin) that receives telemetry reports from the NetWatch
SPA and persists them as zstd-compressed JSONL files on disk.

## Getting Started

```bash
# Build and run locally
make run

# Run tests, lint, and format check
make check

# Docker
docker build -t netwatch-server .
docker run -p 8080:8080 netwatch-server
```

## Rationale

The NetWatch frontend collects latency measurements from the browser but has no
way to persist or aggregate them. This backend provides a minimal
`POST /api/v1/reports` endpoint that buffers incoming reports in memory and
flushes them to compressed files on disk for later analysis.

## Design

The server is structured as an `fx`-wired Go application under `cmd/netwatch-server/`.
Internal packages in `internal/` follow standard Go project layout:

- **`config`**: Loads configuration from environment variables and config files
  via Viper.
- **`handlers`**: HTTP request handlers for the API (health check, report
  ingestion).
- **`reportbuf`**: In-memory buffer that accumulates JSONL report lines and
  flushes to zstd-compressed files when the buffer reaches 10 MiB or every 60
  seconds.
- **`server`**: Chi-based HTTP server with middleware wiring and route
  registration.
- **`healthcheck`**, **`middleware`**, **`logger`**, **`globals`**: Supporting
  infrastructure.

### Configuration

| Variable   | Default            | Description                       |
| ---------- | ------------------ | --------------------------------- |
| `PORT`     | `8080`             | HTTP listen port                  |
| `DATA_DIR` | `./data/reports`   | Directory for compressed reports  |
| `DEBUG`    | `false`            | Enable debug logging              |

### Report storage

Reports are written as `reports-<timestamp>.jsonl.zst` files in `DATA_DIR`.
Each file contains one JSON object per line, compressed with zstd. Files are
created with `O_EXCL` to prevent overwrites.

## TODO

- Add integration test that POSTs a report and verifies the compressed output
- Add report decompression/query endpoint
- Add metrics (Prometheus) for buffer size, flush count, report count
- Add retention policy to prune old report files

## License

MIT. See [LICENSE](LICENSE).

## Author

[@sneak](https://sneak.berlin)