Defines how the primary credential is applied to requests proxied to the upstream.
The type of authentication mechanism: 'header', 'bearer', or 'basic'. For 'basic', store the secret as plain 'user:pass'; the proxy base64-encodes it.
Optional
The header name (e.g., 'x-api-key'). Required for 'header' type; invalid for other types.
Defines how the primary credential is applied to requests proxied to the upstream.