multistage build example

also pin final image on tagged alpine version
~50 ish mb size reduction

Dockerfile

@@ -1,17 +1,27 @@
-FROM alpine:latest
-LABEL MAINTAINER ant@manchestermonkey.co.uk
+ARG CEREBROVER=0.9.4
 
-RUN apk update && apk add bash openjdk8-jre
+FROM alpine:latest as builder
 
-ENV CEREBRO_VER 0.9.4
+ARG CEREBROVER
+ENV CEREBRO_VER=$CEREBROVER
 
 ADD https://github.com/lmenezes/cerebro/releases/download/v${CEREBRO_VER}/cerebro-${CEREBRO_VER}.tgz /
 
 RUN mkdir /cerebro && tar -zxf cerebro-${CEREBRO_VER}.tgz --strip-components 1 -C /cerebro
 
-WORKDIR /cerebro
 
-EXPOSE 9000
+FROM alpine:3.17
+LABEL MAINTAINER ant@manchestermonkey.co.uk
+
+ARG CEREBROVER
+ENV CEREBRO_VER=$CEREBROVER
+
+RUN apk add --no-cache bash openjdk8-jre
+
+COPY --from=builder /cerebro /cerebro
+
+WORKDIR /cerebro
 
-ENTRYPOINT ["/cerebro/bin/cerebro"]
+EXPOSE 9000/tcp
 
+ENTRYPOINT ["/cerebro/bin/cerebro"]