Add Dockerfile for todo backend

Signed-off-by: solidnerd <niclas@mietz.io>

Author: solidnerd

Dockerfile

@@ -1,4 +1,12 @@
-FROM envoyproxy/envoy:latest
-RUN apt-get update
-COPY envoy.yaml /etc/envoy.yaml
-CMD /usr/local/bin/envoy -c /etc/envoy.yaml
+FROM golang:1.11.4-stretch as builder
+WORKDIR $GOPATH/src/todo
+ENV GO111MODULE=on
+COPY go.mod .
+COPY go.sum .
+RUN go mod download
+COPY . .
+RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix nocgo -o /app .
+
+FROM scratch
+COPY --from=builder /app ./
+ENTRYPOINT ["./app"]