Adapting container build

Makefile

@@ -31,7 +31,7 @@ $(RELEASE_NAME):
 	mkdir -p $@
 
 container:
-	podman build -t rexserver -f container/Containerfile .
+	podman build -t rexserver --env REX_VERSION -f container/Containerfile .
 
 clean:
 	make -C ./rex_client clean

container/Containerfile

@@ -1,4 +1,5 @@
 FROM docker.io/golang:alpine as go
+RUN apk add make
 WORKDIR /build
 # ADD rex_server/go.mod rex_server/go.sum ./ # WARNING: Include go.sum
 ADD rex_server/go.mod ./
@@ -8,7 +9,7 @@ RUN go mod download
 # Add the rest of the source
 ADD . .
 
-RUN go build -o ./rexserver ./rex_server/server.go
+RUN make -C rex_server
 
 # Runner image, drop privileges
 FROM docker.io/alpine:latest as runner
@@ -17,7 +18,7 @@ RUN addgroup nonroot nonroot
 WORKDIR /app
 RUN chown nonroot:nonroot /app
 
-COPY --from=go /build/rexserver rexserver
+COPY --from=go /build/rex_server/rexserver rexserver
 EXPOSE 8080
 USER nonroot:nonroot
 CMD ["./rexserver"]