Update Dockerfile to multi-stage build

Signed-off-by: Knut Ahlers <[email protected]>

Dockerfile

@@ -1,16 +1,24 @@
-FROM golang:alpine
-
-LABEL maintainer "Knut Ahlers <[email protected]>"
+FROM golang:alpine as builder
 
 ADD . /go/src/github.com/Luzifer/ots
 WORKDIR /go/src/github.com/Luzifer/ots
 
 RUN set -ex \
- && apk add --update git ca-certificates \
- && go install -ldflags "-X main.version=$(git describe --tags || git rev-parse --short HEAD || echo dev)" \
- && apk del --purge git
+ && apk add --update git \
+ && go install -ldflags "-X main.version=$(git describe --tags || git rev-parse --short HEAD || echo dev)"
+
+FROM alpine:latest
+
+LABEL maintainer "Knut Ahlers <[email protected]>"
+
+RUN set -ex \
+ && apk --no-cache add ca-certificates
+
+COPY --from=builder /go/bin/ots /usr/local/bin/ots
 
 EXPOSE 3000
 
-ENTRYPOINT ["/go/bin/ots"]
+ENTRYPOINT ["/usr/local/bin/ots"]
 CMD ["--"]
+
+# vim: set ft=Dockerfile: