# My service deploys but never becomes healthy

The build succeeds, replicas start, but the deploy stays pending, is marked unhealthy, or never receives traffic.

## What this means

The platform's health check — which verifies your app's port is reachable — never passes, so traffic never shifts to the new replicas.

## Why this can happen

- **Your app isn't listening on the expected port.** Lizard injects a `PORT` environment variable (default container port `3000`) and checks that your app is reachable there. If your app is hardcoded to a different port, or never binds one, the health check fails indefinitely. A Python app is the usual case: `gunicorn` and `uvicorn` bind `127.0.0.1` unless you tell them otherwise, and the probe comes from outside the process. [Python app hosting](https://lizard.build/blog/python-app-hosting#what-a-python-app-actually-needs-from-a-host) has the `--bind 0.0.0.0:$PORT` line each framework needs.
- **The service is accidentally in worker mode.** Setting `containerPort=0` puts a service into [worker mode](https://lizard.build/docs/deploy/workers), which **skips the health check and load-balancer registration entirely**. A service that's supposed to serve HTTP but got flipped to `containerPort=0` will deploy "successfully" and just never serve anything — worker mode hides the underlying startup problem instead of surfacing it.

## Possible solutions

### Check the current port

```bash
lizard port --service api
```

If this prints `worker mode`, the service has `containerPort=0`. Set it back to a real port if this service is meant to serve HTTP:

```bash
lizard port 3000 --service api
lizard redeploy --service api
```

### Confirm your app is listening where Lizard expects

Read the runtime logs for startup errors, and verify the port the app actually bound against what Lizard injected:

```bash
lizard logs --service api
lizard ssh --service api -- env | grep PORT
```

## See also

- [Background Workers](https://lizard.build/docs/deploy/workers) — when `containerPort=0` is (and isn't) the right call.
- [Deployments → lifecycle](https://lizard.build/docs/concepts/deployments#lifecycle) — where the health check sits in a deploy.