Optimise image

Signed-off-by: Paulo Gomes <paulo.gomes@weave.works>

Author: Paulo Gomes

Dockerfile

@@ -5,11 +5,7 @@ ARG XX_VERSION=1.1.0
 
 FROM --platform=$BUILDPLATFORM tonistiigi/xx:${XX_VERSION} AS xx
 
-FROM golang:${GO_VERSION}-${BASE_VARIANT} as gostable
-
-FROM gostable AS go-linux
-
-FROM --platform=$BUILDPLATFORM ${BASE_VARIANT} AS build-deps
+FROM --platform=$BUILDPLATFORM ${BASE_VARIANT} AS build-base
 
 RUN apk add --no-cache \
         bash \
@@ -26,15 +22,10 @@ RUN apk add --no-cache \
 
 COPY --from=xx / /
 
-ARG TARGETPLATFORM
-
-RUN xx-apk add --no-cache \
-        xx-c-essentials 
-
-RUN xx-apk add --no-cache \
-        xx-cxx-essentials 
+FROM build-base AS build-cross
 
 ARG TARGETPLATFORM
+
 RUN xx-apk add --no-cache \
         build-base \
         pkgconfig \
@@ -48,7 +39,6 @@ RUN xx-apk add --no-cache \
 WORKDIR /build
 COPY hack/static.sh .
 
-ARG TARGETPLATFORM
 ENV CC=xx-clang
 ENV CXX=xx-clang++
 
@@ -68,12 +58,25 @@ RUN ./static.sh build_libssh2
 RUN ./static.sh build_libgit2
 
 
-FROM go-${TARGETOS} AS build
+# trimmed removes all non necessary files (i.e. openssl binary).
+FROM build-cross AS trimmed
 
-# Copy cross-compilation tools
-COPY --from=xx / /
-# Copy compiled libraries
-COPY --from=build-deps /usr/local/ /usr/local/
+ARG TARGETPLATFORM
+RUN mkdir -p /trimmed/usr/local/$(xx-info triple)/ && \
+        mkdir -p /trimmed/usr/local/$(xx-info triple)/share
+
+RUN cp -r /usr/local/$(xx-info triple)/lib/ /trimmed/usr/local/$(xx-info triple)/ && \
+        cp -r /usr/local/$(xx-info triple)/lib64/ /trimmed/usr/local/$(xx-info triple)/ | true && \
+        cp -r /usr/local/$(xx-info triple)/include/ /trimmed/usr/local/$(xx-info triple)/ && \
+        cp -r /usr/local/$(xx-info triple)/share/doc/ /trimmed/usr/local/$(xx-info triple)/share/
+
+FROM scratch as libs-arm64
+COPY --from=trimmed /trimmed/ /
+
+FROM scratch as libs-amd64
+COPY --from=trimmed /trimmed/ /
+
+FROM scratch as libs-armv7
+COPY --from=trimmed /trimmed/ /
 
-COPY ./hack/Makefile /Makefile
-COPY ./hack/static.sh /static.sh
+FROM libs-$TARGETARCH$TARGETVARIANT as libs

Dockerfile.test

@@ -1,39 +1,59 @@
 ARG BASE_VARIANT=alpine
+ARG GO_VERSION=1.17.6
+ARG XX_VERSION=1.1.0
 
 ARG LIBGIT2_IMG
 ARG LIBGIT2_TAG
 
-FROM --platform=linux/amd64 ${LIBGIT2_IMG}:${LIBGIT2_TAG} as build-amd64
-FROM --platform=linux/arm64 ${LIBGIT2_IMG}:${LIBGIT2_TAG} as build-arm64
-FROM --platform=linux/arm/v7 ${LIBGIT2_IMG}:${LIBGIT2_TAG} as build-armv7
+FROM ${LIBGIT2_IMG}:${LIBGIT2_TAG} AS build-deps
 
-FROM --platform=$BUILDPLATFORM build-$TARGETARCH$TARGETVARIANT AS build
+FROM --platform=$BUILDPLATFORM tonistiigi/xx:${XX_VERSION} AS xx
 
-RUN apk add clang lld pkgconfig ca-certificates
+FROM --platform=$BUILDPLATFORM golang:${GO_VERSION}-${BASE_VARIANT} as gostable
 
-ARG TARGETPLATFORM
+FROM gostable AS go-linux
 
-# Some dependencies have to installed 
-# for the target platform: https://github.com/tonistiigi/xx#go--cgo
-RUN xx-apk add --no-cache \
-        musl-dev gcc lld binutils-gold
+# Build-base consists of build platform dependencies and xx.
+# These will be used at current arch to yield execute the cross compilations.
+FROM go-${TARGETOS} AS build-base
+
+RUN apk add clang lld pkgconfig
+
+COPY --from=xx / /
+
+# build-go-mod can still be cached at build platform architecture.
+FROM build-base as build-go-mod
 
 WORKDIR /root/smoketest
 COPY tests/smoketest/go.mod .
 COPY tests/smoketest/go.sum .
 RUN go mod download
 
+# Build stage install per target platform
+# dependency and effectively cross compile the application.
+FROM build-go-mod as build
+
+ARG TARGETPLATFORM
+
+# Some dependencies have to installed 
+# for the target platform: https://github.com/tonistiigi/xx#go--cgo
+RUN xx-apk add musl-dev gcc clang lld
+
+WORKDIR /root/smoketest
+
 COPY tests/smoketest/main.go .
+COPY --from=build-deps /usr/local/ /usr/local/
 
 ENV CGO_ENABLED=1
-RUN export LIBRARY_PATH="/usr/local/$(xx-info triple)/lib:/usr/local/$(xx-info triple)/lib64:${LIBRARY_PATH}" && \
+RUN export LIBRARY_PATH="/usr/local/$(xx-info triple):/usr/local/$(xx-info triple)/lib64" && \
     export PKG_CONFIG_PATH="/usr/local/$(xx-info triple)/lib/pkgconfig:/usr/local/$(xx-info triple)/lib64/pkgconfig" && \
-	export FLAGS="$(pkg-config --static --libs --cflags libssh2 openssl libgit2)" && \
-    CGO_LDFLAGS="${FLAGS} -static" \
-	xx-go build \
+    export FLAGS="$(pkg-config --static --libs --cflags libssh2 openssl libgit2)" && \
+    export CGO_LDFLAGS="${FLAGS} -static" && \
+    xx-go build  \
         -ldflags "-s -w" \
         -tags 'netgo,osusergo,static_build' \
-        -o static-test-runner -trimpath main.go;
+        -o static-test-runner -trimpath main.go
+
 
 # Ensure that the generated binary is valid for the target platform
 RUN xx-verify --static static-test-runner

Makefile

@@ -48,7 +48,7 @@ build:
 test:
 	docker buildx build \
 		--platform=$(PLATFORMS) \
-		--tag $(IMG):$(TAG) \
+		--tag $(IMG):$(TAG)-test \
 		--build-arg LIBGIT2_IMG=$(IMG) \
 		--build-arg LIBGIT2_TAG=$(TAG) \
 		--file Dockerfile.test \