Add docker image publish github workflow

.github/workflows/build.yml

@@ -1,4 +1,4 @@
-name: mbusd
+name: build
 
 on:
   push:

.github/workflows/docker-publish.yml

@@ -0,0 +1,62 @@
+name: docker publish
+
+on:
+  workflow_run:
+    workflows: [ 'build' ]
+    types: [ completed ]
+    branches: [ 'master' ]
+    tags: [ 'v*' ]
+
+env:
+  PLATFORMS: linux/amd64,linux/arm64,linux/arm/v7
+  # github.repository as <account>/<repo>
+  IMAGE_NAME: ${{ github.repository }}
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    if: ${{ github.event.workflow_run.conclusion == 'success' }}
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Login to Docker Hub
+        if: github.event_name != 'pull_request'
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      # Extract metadata (tags, labels) for Docker
+      # https://github.com/docker/metadata-action
+      - name: Extract Docker metadata
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ${{ env.IMAGE_NAME }}
+          tags: |
+            type=ref,event=branch
+            type=ref,event=pr
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=sha
+
+      # Build and push Docker image with Buildx (don't push on PR)
+      # https://github.com/docker/build-push-action
+      - name: Build and push Docker image
+        id: build-and-push
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          platforms: ${{ env.PLATFORMS }}
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha,scope=${{ env.IMAGE_NAME }}
+          cache-to: type=gha,mode=max,scope=${{ env.IMAGE_NAME }}

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:latest AS build
+FROM --platform=$BUILDPLATFORM alpine:latest AS build
 RUN apk add --no-cache alpine-sdk cmake linux-headers
 COPY . /mbusd
 WORKDIR /mbusd/build