ci: add Buildkit workflow for multi-image builds

.gitea/workflows/build-images.yml

@@ -0,0 +1,85 @@
+name: Build and Push Docker Images
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'images/**'
+  workflow_dispatch:
+    inputs:
+      image:
+        description: 'Image to build (e.g., terraform-ci)'
+        required: false
+
+env:
+  REGISTRY: gitea.arnodo.fr
+
+jobs:
+  detect-changes:
+    runs-on: docker
+    container:
+      image: alpine/git:latest
+    outputs:
+      matrix: ${{ steps.changes.outputs.matrix }}
+      has_changes: ${{ steps.changes.outputs.has_changes }}
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 2
+
+      - name: Detect changed images
+        id: changes
+        run: |
+          if [ -n "${{ github.event.inputs.image }}" ]; then
+            # Manual trigger - build specific image
+            echo "matrix=[\"${{ github.event.inputs.image }}\"]" >> $GITHUB_OUTPUT
+            echo "has_changes=true" >> $GITHUB_OUTPUT
+          else
+            # Auto-detect changed images
+            CHANGED=$(git diff --name-only HEAD~1 HEAD -- images/ | cut -d'/' -f2 | sort -u | grep -v '^$' || true)
+            if [ -z "$CHANGED" ]; then
+              echo "has_changes=false" >> $GITHUB_OUTPUT
+              echo "matrix=[]" >> $GITHUB_OUTPUT
+            else
+              # Convert to JSON array
+              JSON=$(echo "$CHANGED" | jq -R -s -c 'split("\n") | map(select(length > 0))')
+              echo "matrix=$JSON" >> $GITHUB_OUTPUT
+              echo "has_changes=true" >> $GITHUB_OUTPUT
+            fi
+          fi
+
+  build:
+    needs: detect-changes
+    if: needs.detect-changes.outputs.has_changes == 'true'
+    runs-on: docker
+    strategy:
+      matrix:
+        image: ${{ fromJson(needs.detect-changes.outputs.matrix) }}
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set up Docker Buildx
+        run: |
+          docker buildx create --use --name gitea-builder || docker buildx use gitea-builder
+
+      - name: Login to Gitea Registry
+        run: |
+          echo "${{ secrets.REGISTRY_TOKEN }}" | docker login ${{ env.REGISTRY }} -u ${{ gitea.actor }} --password-stdin
+
+      - name: Build and push
+        run: |
+          IMAGE_NAME="${{ env.REGISTRY }}/damien/${{ matrix.image }}"
+          
+          docker buildx build \
+            --platform linux/amd64 \
+            --tag "${IMAGE_NAME}:latest" \
+            --tag "${IMAGE_NAME}:${{ gitea.sha }}" \
+            --push \
+            ./images/${{ matrix.image }}
+
+      - name: Summary
+        run: |
+          echo "### ✅ Image built and pushed" >> $GITHUB_STEP_SUMMARY
+          echo "" >> $GITHUB_STEP_SUMMARY
+          echo "- **Image**: ${{ env.REGISTRY }}/damien/${{ matrix.image }}" >> $GITHUB_STEP_SUMMARY
+          echo "- **Tags**: latest, ${{ gitea.sha }}" >> $GITHUB_STEP_SUMMARY