The main README.md has instructions for how to run the server and client inside docker. When I follow these instructions, I can start the server fine:
$ export HOST=grpc.nleiva.com
$ export PORT=443
$ make docker-build
...
$ make run-docker-server
docker run -t --rm \
--name my-server \
--publish=443:443 \
server
level=info time=2020-09-17T17:52:10.762406133Z caller=main.go:206 msg="Server listening" port=443
level=info time=2020-09-17T17:52:10.76250748Z caller=main.go:209 msg="Starting gRPC services"
level=info time=2020-09-17T17:52:10.762551842Z caller=main.go:212 msg="Listening for incoming connections"
$ export HOST=grpc.nleiva.com
$ export PORT=443
$ export ID=1
$ make run-docker-client
docker run -t --rm --name my-client -e 1 client
2020/09/17 17:53:57 HOST environment variable not set.
panic: HOST environment variable not set.
goroutine 1 [running]:
log.Panicf(0x8dff0b, 0x20, 0xc0000a3f10, 0x1, 0x1)
/usr/local/go/src/log/log.go:340 +0xc0
main.getenv(0x8d0f0e, 0x4, 0x10, 0xc0000e8100)
/go/src/github.com/nleiva/grpc-tls/client/main.go:32 +0xd1
main.init.ializers()
/go/src/github.com/nleiva/grpc-tls/client/main.go:24 +0x3a
Makefile:39: recipe for target 'run-docker-client' failed
make: *** [run-docker-client] Error 2