workflows/Makefile: build Docker image for MacOS

We build multiarch linux/amd64 and linux/arm64, because MacOS runner can't
build docker images and even if it could that'd be linux/amd64 while we want
linux/arm64 for Apple CPUs.

Unfortunately, given the way GitHub workflows work we can't avoid using a
Makefile helper, there is no easy way to set variables conditionally and/or
use some logic to affect their contents.

We reintroduce build_image_wsc as well here because Windows images can't be
built with buildx using GitHub runners.

.github/workflows/build.yml

@@ -66,10 +66,39 @@ jobs:
   build_image:
     needs: build_cli
     name: Build Docker image
-    runs-on: ${{matrix.os}}
-    strategy:
-      matrix:
-        os: [ubuntu-20.04, windows-2022]
+    runs-on: ubuntu-20.04
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          ref: ${{ github.event.inputs.ref }}
+          fetch-depth: 0
+
+      - name: Set up QEMU
+        if: runner.os != 'Windows'
+        uses: docker/setup-qemu-action@v2
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
+      - name: Set vars
+        id: setvars
+        run: make gh-docker-vars
+
+      - name: Build and push
+        uses: docker/build-push-action@v3
+        with:
+          push: false
+          platforms: linux/amd64,linux/arm64
+          build-args: |
+            REPO=${{ steps.setvars.outputs.repo }}
+            VERSION=${{ steps.setvars.outputs.version }}
+          tags: ${{ steps.setvars.outputs.repo }}:${{ steps.setvars.outputs.version }}${{ steps.setvars.outputs.suffix }}
+
+  build_image_wsc:
+    needs: build_cli
+    name: Build Docker image (Windows Server Core)
+    runs-on: windows-2022
 
     steps:
       - uses: actions/checkout@v2
@@ -100,6 +129,9 @@ jobs:
           ref: ${{ github.event.inputs.ref }}
           fetch-depth: 0
 
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
       # For proper `deps` make target execution.
       - name: Set up Go
         uses: actions/setup-go@v2

Makefile

@@ -25,7 +25,7 @@ IMAGE_REPO=nspccdev/neo-go
 # All of the targets are phony here because we don't really use make dependency
 # tracking for files
 .PHONY: build $(BINARY) deps image docker/$(BINARY) image-latest image-push image-push-latest clean-cluster \
-	test vet lint fmt cover
+	test vet lint fmt cover version gh-docker-vars
 
 build: deps
 	@echo "=> Building binary"
@@ -92,6 +92,15 @@ deps:
 	@CGO_ENABLED=0 \
 	go mod tidy -v
 
+version:
+	@echo $(VERSION)
+
+gh-docker-vars:
+	@echo "::set-output name=file::$(D_FILE)"
+	@echo "::set-output name=version::$(VERSION)"
+	@echo "::set-output name=repo::$(REPO)"
+	@echo "::set-output name=suffix::$(IMAGE_SUFFIX)"
+
 test:
 	@go test ./... -cover