From 4222e297930b4743885d16b44303a8348574da5b Mon Sep 17 00:00:00 2001
From: Yury Kulazhenkov <ykulazhenkov@nvidia.com>
Date: Mon, 25 Nov 2024 10:24:15 +0200
Subject: [PATCH] Fix: multiarch build by using crosscompilation
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Use quay.io/centos/centos:stream9 with the –platform=$BUILDPLATFORM flag,
in this case the image is pulled for the builder host's current architecture.
The BUILDOS and BUILDARCH args are used to download the right go binary for
the build platform.
Cross-compilation occurs in the builder image using TARGETOS and TARGETARCH build arguments to determine the target OS/arch.
These args are set automatically by the multiarch-build process (with docker buildx).
The final container image (registry.access.redhat.com/ubi9/ubi-minimal) is pulled for the correct target architecture, such as amd64 or arm64.

This update fixes support for multiarch builds and speeds up image building, as cross-compilation is faster than compiling on a non-native platform.

Signed-off-by: Yury Kulazhenkov <ykulazhenkov@nvidia.com>
---
 .github/workflows/image-build-test.yaml   |  4 --
 .github/workflows/image-push-main.yaml    |  4 --
 .github/workflows/image-push-release.yaml |  4 --
 cmd/Dockerfile                            | 45 ++++++++++++++++-------
 4 files changed, 31 insertions(+), 26 deletions(-)

diff --git a/.github/workflows/image-build-test.yaml b/.github/workflows/image-build-test.yaml
index 87bff92e..917ce663 100644
--- a/.github/workflows/image-build-test.yaml
+++ b/.github/workflows/image-build-test.yaml
@@ -27,9 +27,5 @@ jobs:
         with:
           context: .
           push: false
-          # no need to explicitly set goarch, 
-          # correct arch will be selected for each build platform 
-          build-args: |
-            goarch=
           platforms: ${{ env.BUILD_PLATFORMS }}
           file: ./cmd/Dockerfile
diff --git a/.github/workflows/image-push-main.yaml b/.github/workflows/image-push-main.yaml
index 3419ed10..5fe74d24 100644
--- a/.github/workflows/image-push-main.yaml
+++ b/.github/workflows/image-push-main.yaml
@@ -45,10 +45,6 @@ jobs:
         with:
           context: .
           push: true
-          # no need to explicitly set goarch, 
-          # correct arch will be selected for each build platform 
-          build-args: |
-            goarch=
           platforms: ${{ env.BUILD_PLATFORMS }}
           tags: |
             ${{ env.IMAGE_NAME }}:latest
diff --git a/.github/workflows/image-push-release.yaml b/.github/workflows/image-push-release.yaml
index 120672a7..f45fe53b 100644
--- a/.github/workflows/image-push-release.yaml
+++ b/.github/workflows/image-push-release.yaml
@@ -47,10 +47,6 @@ jobs:
         with:
           context: .
           push: true
-          # no need to explicitly set goarch, 
-          # correct arch will be selected for each build platform 
-          build-args: |
-            goarch=
           platforms: ${{ env.BUILD_PLATFORMS }}
           tags: |
             ${{ steps.docker_meta.outputs.tags }}
diff --git a/cmd/Dockerfile b/cmd/Dockerfile
index fa677e40..326e1157 100644
--- a/cmd/Dockerfile
+++ b/cmd/Dockerfile
@@ -1,27 +1,42 @@
-FROM quay.io/centos/centos:stream9 as builder
+FROM --platform=$BUILDPLATFORM quay.io/centos/centos:stream9 AS builder
 
 RUN mkdir /workdir
-WORKDIR /workdir
+# Support overriding target GOARCH during `make docker-build`
+ARG goarch=
 
-COPY go.mod .
+# these variable are automatically set during the multiarch build by docker buildx
+ARG TARGETOS
+ARG TARGETARCH
+ENV TARGETOS=${TARGETOS:-linux}
+ENV TARGETARCH=${TARGETARCH:-amd64}
+
+ARG BUILDOS
+ARG BUILDARCH
+ENV BUILDOS=${BUILDOS:-linux}
+ENV BUILDARCH=${BUILDARCH:-amd64}
+
+ENV GOOS=${TARGETOS}
+ENV GOARCH=${goarch:-$TARGETARCH}
+ENV CGO_ENABLED=0
+ENV GOFLAGS=-mod=vendor
+
+WORKDIR /workdir
 
 RUN dnf install -y wget
 
+COPY go.mod .
+COPY go.sum .
+
 RUN GO_VERSION=$(sed -En 's/^go +(.*)$/\1/p' go.mod) && \
-    wget https://dl.google.com/go/go${GO_VERSION}.linux-amd64.tar.gz && \
-    tar -C /usr/local -xzf go${GO_VERSION}.linux-amd64.tar.gz && \
-    rm go${GO_VERSION}.linux-amd64.tar.gz
+    wget https://dl.google.com/go/go${GO_VERSION}.${BUILDOS}-${BUILDARCH}.tar.gz && \
+    tar -C /usr/local -xzf go${GO_VERSION}.${BUILDOS}-${BUILDARCH}.tar.gz && \
+    rm go${GO_VERSION}.${BUILDOS}-${BUILDARCH}.tar.gz
 
-ENV PATH /usr/local/go/bin:$PATH
+ENV PATH=/usr/local/go/bin:$PATH
 
-COPY . .
+RUN go mod download
 
-ENV GOOS linux
-# Support overriding target GOARCH during `make docker-build`
-ARG goarch=amd64
-ENV GOARCH=$goarch
-ENV CGO_ENABLED 0
-ENV GOFLAGS -mod=vendor
+COPY . .
 
 RUN mkdir /workdir/bin
 RUN go build -tags no_openssl -o /workdir/bin/ovs ./cmd/plugin
@@ -30,6 +45,8 @@ RUN go build -tags no_openssl -o /workdir/bin/ovs-mirror-producer ./cmd/mirror-p
 RUN go build -tags no_openssl -o /workdir/bin/ovs-mirror-consumer ./cmd/mirror-consumer
 
 FROM registry.access.redhat.com/ubi9/ubi-minimal
+
 RUN microdnf install -y findutils
+
 COPY --from=builder /workdir/.version /.version
 COPY --from=builder /workdir/bin/* /