Override hostname with '@aws' only if hostname override is not specified.

pkg/model/components/kubeproxy.go

@@ -69,8 +69,11 @@ func (b *KubeProxyOptionsBuilder) BuildOptions(o interface{}) error {
 	cloudProvider := kops.CloudProviderID(clusterSpec.CloudProvider)
 	if cloudProvider == kops.CloudProviderAWS {
 		// Use the hostname from the AWS metadata service
+		// if hostnameOverride is not set.
+		if config.HostnameOverride == "" {
 			config.HostnameOverride = "@aws"
 		}
+	}
 
 	return nil
 }