use matrix variables

.github/workflows/go-release.yml

@@ -20,8 +20,6 @@ on:
 env:
   REGISTRY: ghcr.io  # default is docker.io
   IMAGE_NAME: ${{ github.repository }} # -tools  # e.g. user/fancy-project[-suffix]
-  ARCH: arm64 # for Makefile where we still use ARCH
-  GOOS: linux # for Makefile
 
 jobs:
   go-release-ghcr:
@@ -30,6 +28,13 @@ jobs:
     permissions:
       packages: write  # required to write to container registry
       #   contents: write  # for releases (e.g. go-releaser)
+    strategy:
+      matrix:
+        include:
+          - goos: linux
+            goarch: arm64
+          #- goos: linux
+          #  arch: amd64
     steps:
 
       # checkout is essential if you use a different context than "."
@@ -58,9 +63,9 @@ jobs:
         run: |
           make build
         env:
-          GOOS: ${{ env.GOOS }}
+          GOOS: ${{ matrix.goos }}
           # todo refactor Makefile to use GOARCH
-          ARCH: ${{ env.ARCH }}
+          ARCH: ${{ matrix.goarch }}
           CI: true
           RELEASE_NAME: ${{ env.RELEASE_NAME }}
           RELEASE_VERSION: ${{ env.RELEASE_VERSION }}
@@ -85,27 +90,27 @@ jobs:
 
       # QEMU is a generic and open source machine & userspace emulator and virtualizer.
       # to emulating a complete machine in software without any need for hardware virtualization support
-#      - name: Set up QEMU static binaries
-#        uses: docker/setup-qemu-action@v3
-#        with:
-#          # since we run platform specific builds in parallel, we only need the current platform
-#          platforms: ${{ env.GOOS }}/${{ env.ARCH }}
+      # it's required at least if you RUN things in your docker build and the target platform
+      # is *NOT* the platform of the runner (or you get messages like "exec /bin/sh: exec format error")
+      - name: Set up QEMU static binaries
+        uses: docker/setup-qemu-action@v3
+        with:
+          # since we run platform specific builds in parallel, we only need the current platform
+          platforms: ${{ env.GOOS }}/${{ env.ARCH }}
 
       # explicit setup-buildx action required? No, at least standard worker comes with cli plugin
-#      - name: Set up Docker Buildx
-#        uses: docker/setup-buildx-action@v3
-#        if: github.ref == format('refs/heads/{0}', github.event.repository.default_branch) # run only on main
-
+      # - name: Set up Docker Buildx
+      #   uses: docker/setup-buildx-action@v3
 
       # https://github.com/docker/build-push-action?tab=readme-ov-file#usage
       - name: Build docker image
         id: build # so we can reference this step as ${{ steps.build.outputs.digest }} in export step
         uses: docker/build-push-action@v5
         with:
           #${{ matrix.platform }}
-          platforms:  ${{ env.GOOS }}/${{ env.ARCH }}
+          platforms:  ${{ matrix.goos }}/${{ matrix.goarch }}
           context: ./go
-          # for none-multistage use true, otherwise false
+          # for none-multistage use true and merge manifest in 2nd job, otherwise false
           push: true
           # for multistage O NOT specify 'tags' here (error "get can't push tagged ref by digest")
           tags: ${{ steps.meta.outputs.tags }}