# Gateway Flags and Environment Variables

> All CLI flags and REP_GATEWAY_* environment variables for configuring the gateway. Port, mode, upstream, strict mode, hot reload, logging, CORS, and rate limiting options.

Source: https://rep-protocol.dev/reference/gateway-flags/

The gateway is configured via command-line flags or environment variables. Flags take precedence over env vars.

## Command-line flags

```
rep-gateway [flags]
```

| Flag | Default | Description |
|---|---|---|
| `--mode` | `proxy` | Operating mode: `proxy` or `embedded` |
| `--upstream` | `localhost:80` | Upstream server address (proxy mode only) |
| `--port` | `8080` | Listen port |
| `--static-dir` | `/usr/share/nginx/html` | Static file directory (embedded mode only) |
| `--manifest` | — | Path to `.rep.yaml` manifest (validates variables, injects [defaults](/guides/manifest/#defaults)) |
| `--env-file` | — | Path to `.env` file (env vars take precedence) |
| `--strict` | `false` | Exit on guardrail warnings |
| `--hot-reload` | `false` | Enable hot reload SSE endpoint |
| `--hot-reload-mode` | `signal` | Detection mode: `file_watch`, `signal`, `poll` |
| `--watch-path` | — | Path to watch for changes (file_watch mode) |
| `--poll-interval` | `30s` | Config poll interval (poll mode) |
| `--log-format` | `json` | Log format: `json` or `text` |
| `--log-level` | `info` | Log level: `debug`, `info`, `warn`, `error` |
| `--allowed-origins` | — | Comma-separated CORS origins for `/rep/session-key` |
| `--tls-cert` | — | Path to TLS certificate |
| `--tls-key` | — | Path to TLS private key |
| `--health-port` | — | Separate port for health check endpoint |

## Environment variables

Every flag can be set via environment variable with the `REP_GATEWAY_` prefix:

```bash
REP_GATEWAY_MODE=proxy
REP_GATEWAY_UPSTREAM=localhost:80
REP_GATEWAY_PORT=8080
REP_GATEWAY_STRICT=true
REP_GATEWAY_HOT_RELOAD=true
REP_GATEWAY_HOT_RELOAD_MODE=signal
REP_GATEWAY_LOG_FORMAT=json
REP_GATEWAY_LOG_LEVEL=info
REP_GATEWAY_ALLOWED_ORIGINS=https://app.example.com,https://staging.example.com
```

## Precedence order

1. Command-line flags (highest)
2. Environment variables (`REP_GATEWAY_*`)
3. Manifest file settings (lowest)

## Common configurations

### Proxy mode (development)

```bash
rep-gateway \
  --mode proxy \
  --upstream localhost:5173 \
  --port 8080 \
  --hot-reload
```

### Embedded mode (production)

```bash
rep-gateway \
  --mode embedded \
  --static-dir /static \
  --port 8080 \
  --strict \
  --log-format json \
  --allowed-origins https://app.example.com
```

### Kubernetes sidecar

```bash
rep-gateway \
  --mode proxy \
  --upstream localhost:80 \
  --port 8080 \
  --strict \
  --hot-reload \
  --hot-reload-mode file_watch \
  --watch-path /config \
  --health-port 9090
```