ci(container): verify published immutable image

.github/workflows/verify-published-image.yml

@@ -0,0 +1,69 @@
+name: Verify published PortfolioHub image
+
+on:
+  workflow_dispatch:
+    inputs:
+      version:
+        description: "Strict release tag (for example v0.1.1)"
+        required: true
+        type: string
+      commit:
+        description: "Exact 40-character lowercase source commit"
+        required: true
+        type: string
+
+permissions:
+  contents: read
+  packages: read
+
+jobs:
+  verify:
+    runs-on: ubuntu-24.04
+    steps:
+      - name: Validate immutable selectors and image contract
+        env:
+          REGISTRY_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          ACTOR: ${{ github.actor }}
+          VERSION: ${{ inputs.version }}
+          COMMIT: ${{ inputs.commit }}
+          IMAGE: ghcr.io/fourblocks2020/portfolio-hub
+        run: |
+          set -euo pipefail
+          [[ "$VERSION" =~ ^v(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)$ ]]
+          [[ "$COMMIT" =~ ^[0-9a-f]{40}$ ]]
+          short_sha="${COMMIT:0:12}"
+
+          printf '%s' "$REGISTRY_TOKEN" | docker login ghcr.io --username "$ACTOR" --password-stdin >/dev/null
+          version_raw="$(docker buildx imagetools inspect --raw "$IMAGE:$VERSION")"
+          source_raw="$(docker buildx imagetools inspect --raw "$IMAGE:$short_sha")"
+          version_digest="sha256:$(printf '%s' "$version_raw" | sha256sum | cut -d' ' -f1)"
+          source_digest="sha256:$(printf '%s' "$source_raw" | sha256sum | cut -d' ' -f1)"
+          test "$version_digest" = "$source_digest"
+
+          docker pull "$IMAGE@$version_digest" >/dev/null
+          test "$(docker image inspect "$IMAGE@$version_digest" --format '{{.Architecture}}')" = amd64
+          test "$(docker image inspect "$IMAGE@$version_digest" --format '{{.Config.User}}')" = 10001:10001
+          test "$(docker image inspect "$IMAGE@$version_digest" --format '{{index .Config.Labels "org.opencontainers.image.revision"}}')" = "$COMMIT"
+          test "$(docker image inspect "$IMAGE@$version_digest" --format '{{index .Config.Labels "org.opencontainers.image.version"}}')" = "$VERSION"
+          test "$(docker image inspect "$IMAGE@$version_digest" --format '{{index .Config.Labels "org.opencontainers.image.source"}}')" = https://github.com/fourblocks2020/portfolio-hub
+
+          if docker buildx imagetools inspect "$IMAGE:latest" >/dev/null 2>&1; then
+            echo "mutable latest selector exists" >&2
+            exit 1
+          fi
+
+          echo "digest=$version_digest"
+          echo "version_selector=$IMAGE:$VERSION"
+          echo "source_selector=$IMAGE:$short_sha"
+          echo "immutable=$IMAGE@$version_digest"
+          {
+            echo "## Verified published PortfolioHub image"
+            echo
+            echo "- digest: \`$version_digest\`"
+            echo "- version selector: \`$IMAGE:$VERSION\`"
+            echo "- source selector: \`$IMAGE:$short_sha\`"
+            echo "- source commit: \`$COMMIT\`"
+            echo "- architecture: \`linux/amd64\`"
+            echo "- runtime user: \`10001:10001\`"
+            echo "- latest: absent"
+          } >> "$GITHUB_STEP_SUMMARY"