Please change $CLUSTER_NAME, $REGION_NAME, $PROJECT_NAME, $APP_NAME, $LOCAL_PORT and $REMOTE_PORT to your need
gcloud container clusters get-credentials $CLUSTER_NAME --region $REGION_NAME> --project $PROJECT_NAME;
export POD_NAME=$(kubectl get pods -n $NAME_SPACE -l "app=$APP_NAME" -o jsonpath="{.items[0].metadata.name}");
kubectl -n dev port-forward --address 127.0.0.1 $POD_NAME $LOCAL_PORT:$REMOTE_PORT
# in one line
gcloud container clusters get-credentials $CLUSTER_NAME --region $REGION_NAME> --project $PROJECT_NAME; export POD_NAME=$(kubectl get pods -n $NAME_SPACE -l "app=$APP_NAME" -o jsonpath="{.items[0].metadata.name}"); kubectl -n dev port-forward --address 127.0.0.1 $POD_NAME $LOCAL_PORT:$REMOTE_PORT