Reuse go docker build cache (#1218)

environments/go/Dockerfile

@@ -1,21 +1,24 @@
 ARG GO_VERSION=1.9.2
 
+FROM ubuntu:18.04 AS base
+WORKDIR /
+RUN apt update && apt install -y ca-certificates && rm -rf /var/lib/apt/lists/*
+
 FROM golang:${GO_VERSION} AS builder
 
 ENV GOPATH /usr
 ENV APP	   ${GOPATH}/src/github.com/fission/fission/environments/go
 
+WORKDIR ${APP}
+
 ADD context	    ${APP}/context
 ADD server.go   ${APP}
 
-WORKDIR ${APP}
 RUN go get
 RUN go build -a -o /server server.go
 
-FROM ubuntu:18.04
-WORKDIR /
+FROM base
 COPY --from=builder /server /
-RUN apt update && apt install -y ca-certificates && rm -rf /var/lib/apt/lists/*
 
 ENTRYPOINT ["/server"]
 EXPOSE 8888

environments/go/Dockerfile-1.11.4

@@ -1,21 +1,24 @@
 ARG GO_VERSION=1.11.4
 
+FROM ubuntu:18.04 AS base
+WORKDIR /
+RUN apt update && apt install -y ca-certificates && rm -rf /var/lib/apt/lists/*
+
 FROM golang:${GO_VERSION} AS builder
 
 ENV GOPATH /usr
 ENV APP	   ${GOPATH}/src/github.com/fission/fission/environments/go
 
+WORKDIR ${APP}
+
 ADD context	    ${APP}/context
 ADD server.go   ${APP}
 
-WORKDIR ${APP}
 RUN go get
 RUN go build -a -o /server server.go
 
-FROM ubuntu:18.04
-WORKDIR /
+FROM base
 COPY --from=builder /server /
-RUN apt update && apt install -y ca-certificates && rm -rf /var/lib/apt/lists/*
 
 ENTRYPOINT ["/server"]
 EXPOSE 8888