# Endpoint Monitor Service

A typed FastAPI service that stores endpoint monitors in concurrency-safe process memory and
runs SSRF-aware on-demand HTTP checks.

## Quick start

Requires Python 3.12.

```sh
python -m venv .venv
. .venv/bin/activate
pip install -e '.[dev]'
uvicorn app.main:app --reload
```

OpenAPI is at `http://localhost:8000/docs`.

```sh
curl -s -X POST http://localhost:8000/monitors \
  -H 'content-type: application/json' \
  -d '{"name":"Example","url":"https://example.com","expected_status":200}'
curl -s -X POST http://localhost:8000/monitors/UUID/check
curl -s http://localhost:8000/monitors/UUID/status
```

See `docs/service-contract.md` for routes, schemas, status semantics, error behavior, security,
and architecture.

## Configuration

All settings are validated at startup and use the `MONITOR_` prefix:

| Variable | Default | Constraint |
|---|---:|---|
| `MONITOR_HOST` | `0.0.0.0` | bind host |
| `MONITOR_PORT` | `8000` | 1..65535 |
| `MONITOR_LOG_LEVEL` | `INFO` | logging level |
| `MONITOR_CHECK_TIMEOUT_SECONDS` | `5` | >0, <=30 |
| `MONITOR_MAX_REDIRECTS` | `3` | 0..10 |

## Quality checks

```sh
ruff format --check .
ruff check .
mypy app
pytest
./scripts/verify.sh
```

Tests use mocked HTTP transports and cover typed CRUD/error behavior, concurrent state changes,
status persistence, timeout-safe checking, DNS/private-address blocking, redirect revalidation,
and log redaction. No test sends outbound traffic.

## Containers

```sh
docker build -t endpoint-monitor .
docker run --rm -p 8000:8000 endpoint-monitor
# or
docker compose up --build
```

The image runs as an unprivileged user, uses one worker, and has a health check.

## Important limitation

Storage is deliberately process-local and ephemeral. Restarting loses every monitor. Multiple
workers or replicas each have independent data and readiness only establishes that the local
process can serve requests. Use one worker; add a shared database before scaling horizontally.