# Endpoint Monitor API

A typed FastAPI service for process-local endpoint monitors and secure, on-demand HTTP checks.

## Features

- CRUD monitor resources and current-status retrieval
- bounded HTTP/HTTPS checks with latency measurement
- SSRF protection on every DNS lookup and redirect hop
- JSON logs with URL credentials, query strings, and fragments redacted
- health/readiness endpoints and validated `MONITOR_` environment settings
- concurrency-safe in-memory state

## Layout

- `docs/service-contract.md` — API and architecture contract
- `app/` — settings, models, store, checker, logging, and FastAPI routes
- `tests/` — API and checker/security tests using mocked outbound HTTP
- `docs/verification.md` — validation commands and expected evidence

## Run locally

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

Open `http://127.0.0.1:8000/docs`.

## Examples

```bash
curl -sS -X POST http://127.0.0.1:8000/monitors \
  -H 'content-type: application/json' \
  -d '{"name":"example","url":"https://example.com/"}'
curl -sS http://127.0.0.1:8000/monitors
curl -sS -X POST http://127.0.0.1:8000/monitors/MONITOR_ID/check
curl -sS http://127.0.0.1:8000/monitors/MONITOR_ID/status
curl -sS http://127.0.0.1:8000/healthz
curl -sS http://127.0.0.1:8000/readyz
```

PUT accepts the same body as POST and replaces the mutable fields. DELETE returns 204. Unknown IDs return the JSON error envelope documented in the service contract.

## Configuration

All settings are validated at startup.

| Variable | Default | Meaning |
|---|---:|---|
| `MONITOR_REQUEST_TIMEOUT_SECONDS` | `5.0` | Total check timeout, range 0.1–30 |
| `MONITOR_MAX_REDIRECTS` | `5` | Manual redirect limit, range 0–10 |
| `MONITOR_MAX_MONITORS` | `1000` | Process-local monitor capacity |
| `MONITOR_LOG_LEVEL` | `INFO` | Python log level |

Private, loopback, link-local, multicast, reserved, and otherwise non-global resolved addresses are rejected. URL userinfo is rejected. Only HTTP and HTTPS are accepted.

## Quality checks

```bash
ruff format --check .
ruff check .
mypy app
pytest -q
```

## Container

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

The container has a non-root user and one worker intentionally. State is process-local and is lost on restart; multiple workers/replicas do not share monitors. Use a durable shared database before horizontal scaling or production persistence is required.