# No Discovery

## Envoy xDS Only

### Description

Grey Matter Control uses xds-only to act as a stand-alone Envoy xDS server and request sink.

### Usage

To use xds-only mode, set the following environment variables:

```bash
GM_CONTROL_CMD=xds-only
```

Grey Matter Control using xds-only discovery runs the collector as only an xDS server and request logging sink. Commonly used when running a pool of gm-control as standalone xDS servers, or when co-locating gm-control as an xDS sidecar.

#### Command Line

To use the command line, run gm-control with

```bash
gm-control xds-only <global-flags>
```

**Help**

For help or to list available options for xds-only discovery using the cli, run `gm-control xds-only --help`.