> ## Documentation Index
> Fetch the complete documentation index at: https://proxy-hopper.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Environment Variables

> All PROXY_HOPPER_* environment variables and what they do.

All server settings can be configured via environment variables. Environment variables are overridden by the `server:` block in `config.yaml`, which is in turn overridden by CLI flags.

See [Config Reference](/admin/configuration/reference#config-priority) for the full priority order.

## Variable reference

| Variable                      | Default                                  | Description                                                     |
| ----------------------------- | ---------------------------------------- | --------------------------------------------------------------- |
| `PROXY_HOPPER_HOST`           | `0.0.0.0`                                | Bind address for the proxy server                               |
| `PROXY_HOPPER_PORT`           | `8080`                                   | Proxy server listen port                                        |
| `PROXY_HOPPER_ADMIN`          | `false`                                  | Set to `true` to enable the admin server (GraphQL + REST)       |
| `PROXY_HOPPER_ADMIN_PORT`     | `8081`                                   | Admin server listen port                                        |
| `PROXY_HOPPER_LOG_LEVEL`      | `INFO`                                   | Log verbosity — `TRACE`, `DEBUG`, `INFO`, `WARNING`, or `ERROR` |
| `PROXY_HOPPER_LOG_FORMAT`     | `text`                                   | Log format — `text` or `json`. Use `json` for Docker/Kubernetes |
| `PROXY_HOPPER_LOG_FILE`       | stderr                                   | Write logs to this file path instead of stderr                  |
| `PROXY_HOPPER_BACKEND`        | `memory`                                 | IP pool backend — `memory` or `redis`                           |
| `PROXY_HOPPER_REDIS_URL`      | `redis://localhost:6379/0`               | Redis connection URL (used when `BACKEND=redis`)                |
| `PROXY_HOPPER_METRICS`        | `false`                                  | Set to `true` to enable the Prometheus `/metrics` endpoint      |
| `PROXY_HOPPER_METRICS_PORT`   | `9090`                                   | Port for the metrics server                                     |
| `PROXY_HOPPER_PROBE`          | `true`                                   | Set to `false` to disable the background IP health prober       |
| `PROXY_HOPPER_PROBE_INTERVAL` | `60`                                     | Seconds between background probe rounds                         |
| `PROXY_HOPPER_PROBE_TIMEOUT`  | `10`                                     | Per-IP probe HTTP timeout in seconds                            |
| `PROXY_HOPPER_PROBE_URLS`     | `https://1.1.1.1,https://www.google.com` | Comma-separated list of URLs to probe through each IP           |

<Note>
  `server.authServer` (managed auth / token server config) is YAML-only — there is no `PROXY_HOPPER_AUTH_SERVER_*` variable. See [Config Reference — authServer](/admin/configuration/reference#authserver).
</Note>

## Docker Compose example

```yaml theme={}
services:
  proxy-hopper:
    image: ghcr.io/cams-data/proxy-hopper:latest-redis
    environment:
      PROXY_HOPPER_BACKEND: redis
      PROXY_HOPPER_REDIS_URL: redis://redis:6379/0
      PROXY_HOPPER_LOG_FORMAT: json
      PROXY_HOPPER_LOG_LEVEL: INFO
      PROXY_HOPPER_METRICS: "true"
      PROXY_HOPPER_METRICS_PORT: "9090"
```

## Kubernetes example

```yaml theme={}
env:
  - name: PROXY_HOPPER_BACKEND
    value: redis
  - name: PROXY_HOPPER_REDIS_URL
    value: redis://redis:6379/0
  - name: PROXY_HOPPER_LOG_FORMAT
    value: json
  - name: PROXY_HOPPER_METRICS
    value: "true"
```

<Note>
  Proxy Hopper ignores the Kubernetes-injected `PROXY_HOPPER_PORT` service-link variable by default (controlled via the `enableServiceLinks: false` Helm value). This prevents the injected variable from overriding the `server.port` field in your config.
</Note>