* Add grpc health check. Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com> * fix missing package. Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com> * fix readme.. Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com> * fix vet Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>