add workflow

Author: alessio-pascolini

.github/workflows/build-push.yml

@@ -0,0 +1,53 @@
+---
+name: ci
+
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  docker:
+    strategy:
+      matrix:
+        runner:
+          - ubuntu-latest
+          - ubuntu-24.04-arm
+    runs-on: ${{ matrix.runner }}
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3.3.0
+
+      - name: Setup Docker buildx
+        uses: docker/setup-buildx-action@v2.5.0
+
+      - name: Log into GitHub registry
+        uses: docker/login-action@v2.1.0
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract Docker metadata
+        id: meta
+        uses: docker/metadata-action@v4.3.0
+        with:
+          images: ghcr.io/${{ github.repository_owner }}/postfix-exporter
+
+      # 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@v4.0.0
+        with:
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+          file: Dockerfile