Build: Use Github runners to build and sign container images on new tags

.github/workflows/release-container-image.yml

@@ -0,0 +1,56 @@
+# This action listens on new tags, generates a new container image
+# sign it and upload it to the container registry.
+
+name: Release container image
+on:
+  push:
+    tags:
+      - "container-image/**"
+    branches:
+      - "test/image-**"
+  workflow_dispatch:
+
+permissions:
+  id-token: write
+  packages: write
+  contents: read
+  attestations: write
+
+env:
+  REGISTRY: ghcr.io/${{ github.repository_owner }}
+  REGISTRY_USER: ${{ github.actor }}
+  REGISTRY_PASSWORD: ${{ github.token }}
+  IMAGE_NAME: dangerzone/dangerzone
+
+jobs:
+  build-container-image:
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v4
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: USERNAME
+          password: ${{ github.token }}
+
+      - name: Build and push the dangerzone image
+        id: build-image
+        run: |
+          sudo apt-get install -y python3-poetry
+          python3 ./install/common/build-image.py
+          echo ${{ github.token }} | podman login ghcr.io -u USERNAME --password-stdin
+
+          # Load the image with the final name directly
+          gunzip -c share/container.tar.gz | podman load
+          FINAL_IMAGE_NAME="${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}"
+          podman tag dangerzone.rocks/dangerzone "$FINAL_IMAGE_NAME"
+          podman push "$FINAL_IMAGE_NAME" --digestfile=digest
+          echo "digest=$(cat digest)" >> "$GITHUB_OUTPUT"
+
+      - name: Generate artifact attestation
+        uses: actions/attest-build-provenance@v1
+        with:
+          subject-name: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          subject-digest: "${{ steps.build-image.outputs.digest }}"
+          push-to-registry: true