Add workflow

.github/workflows/build.yml

@@ -0,0 +1,71 @@
+name: Build
+
+on:
+  pull_request:
+    paths-ignore:
+    - 'README.md'
+    - 'LICENSE'
+    - '.github/**'
+    - '!.github/workflows/build.yml'
+  push:
+    branches:
+    - main
+    tags: '[0-9]+.[0-9]+.[0-9]+'
+    paths-ignore:
+    - 'README.md'
+    - 'LICENSE'
+    - '.github/**'
+    - '!.github/workflows/build.yml'
+  release:
+    types:
+    - created
+
+jobs:
+  docker:
+    name: Build and Push Docker Image
+    if: ${{ github.event_name != 'pull_request' || github.event.pull_request.head.repo.full_name == 'ls1intum/Pyris' }}
+    runs-on: ubuntu-latest
+    steps:
+    - name: Compute Tag
+      uses: actions/github-script@v6
+      id: compute-tag
+      with:
+        result-encoding: string
+        script: |
+          if (context.eventName === "pull_request") {
+            return "pr-" + context.issue.number;
+          }
+          if (context.eventName === "release") {
+            return "latest";
+          }
+          if (context.eventName === "push") {
+            if (context.ref.startsWith("refs/tags/")) {
+              return context.ref.slice(10);
+            }
+            if (context.ref === "refs/heads/main") {
+              return "latest";
+            }
+          }
+          return "FALSE";
+    - uses: actions/checkout@v3
+    - name: Set up QEMU
+      uses: docker/setup-qemu-action@v2
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v2
+    # Build and Push to GitHub Container Registry
+    - name: Login to GitHub Container Registry
+      uses: docker/login-action@v2
+      if: ${{ steps.compute-tag.outputs.result != 'FALSE' }}
+      with:
+        registry: ghcr.io
+        username: ${{ github.repository_owner }}
+        password: ${{ secrets.GITHUB_TOKEN }}
+    - name: Build and Push to GitHub Container Registry
+      uses: docker/build-push-action@v4
+      if: ${{ steps.compute-tag.outputs.result != 'FALSE' }}
+      with:
+        platforms: amd64, arm64
+        file: ./Dockerfile
+        context: .
+        tags: ghcr.io/ls1intum/pyris:${{ steps.compute-tag.outputs.result }}
+        push: true