Edit config.yaml
$ go build
$ sudo ./go-sms-api # sudo is required
$ export GO111MODULE=off
$ go get github.com/grpc-ecosystem/grpc-gateway
$ go get github.com/envoyproxy/protoc-gen-validate
$ cd ~/go/src/github.com/grpc-ecosystem/grpc-gateway
$ mkdir third_party && cd third_party
$ git clone https://github.com/googleapis/googleapis.git