Add an option to preserve the ForwardAuth Server Location header

pkg/provider/kubernetes/crd/kubernetes.go

@@ -790,6 +790,7 @@ func createForwardAuthMiddleware(k8sClient Client, namespace string, auth *traef
 		AuthRequestHeaders:       auth.AuthRequestHeaders,
 		AddAuthCookiesToResponse: auth.AddAuthCookiesToResponse,
 		ForwardBody:              auth.ForwardBody,
+		PreserveLocationHeader:   auth.PreserveLocationHeader,
 	}
 	forwardAuth.SetDefaults()
 

pkg/provider/kubernetes/crd/traefikio/v1alpha1/middleware.go

@@ -165,6 +165,8 @@ type ForwardAuth struct {
 	ForwardBody bool `json:"forwardBody,omitempty"`
 	// MaxBodySize defines the maximum body size in bytes allowed to be forwarded to the authentication server.
 	MaxBodySize *int64 `json:"maxBodySize,omitempty"`
+	// PreserveLocationHeader defines whether to forward the Location header to the client as is or prefix it with the domain name of the authentication server.
+	PreserveLocationHeader bool `json:"preserveLocationHeader,omitempty"`
 }
 
 // ClientTLS holds the client TLS configuration.