With Docker running, run the following command to build the grpc-demo-protogen image.
docker build -t grpc-demo-protogen -f ./docker/Dockerfile.protogen ./docker
This will only need to be done once or whenever the Dockerfile.protogen is updated. At least, until the image is available in a container registry for download.
Once the image is built, to generate the protobuf files from the .proto files defined for the service run the following:
make proto
Which simply runs the following docker run
docker run --rm -v $(pwd):/opt/src grpc-demo-protogen:latest
The reason for using the docker image is that the protoc compiler and plugins used are version locked so that the service can be consistently rebuilt and remain functional despite changes new versions of the protoc compiler introduce going forward. Tool dependency version locking.