Fix sign job failure in container publish workflow by handling multiline tag outputs safely

.github/workflows/container.yml

@@ -0,0 +1,200 @@
+# Builds and publishes the funannotate container image to GitHub Container
+# Registry (GHCR), signs it with Cosign (Sigstore), attaches SLSA provenance
+# attestations, and verifies the signature.
+#
+# - Every push of a v* tag: builds the image (./Dockerfile) and publishes it
+#   as ghcr.io/<owner>/funannotate:vX.Y.Z and :X.Y.Z, plus :latest for stable
+#   (non-prerelease) releases. workflow_dispatch allows a manual rebuild.
+
+name: Build and Sign Container Image
+
+on:
+  push:
+    tags:
+      - 'v*'
+  workflow_dispatch:
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
+permissions:
+  contents: read
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    outputs:
+      tags: ${{ steps.meta.outputs.tags }}
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v5
+
+      - name: Compute image tags
+        id: meta
+        env:
+          REF_NAME: ${{ github.ref_name }}
+          REF_TYPE: ${{ github.ref_type }}
+          REGISTRY: ${{ env.REGISTRY }}
+          IMAGE_NAME: ${{ env.IMAGE_NAME }}
+        run: |
+          ref="${REF_NAME}"
+          version="${ref#v}"
+          prerelease="false"
+          case "$version" in *-*) prerelease="true" ;; esac
+          {
+            echo "tags<<_EOF_"
+            echo "${REGISTRY}/${IMAGE_NAME}:${ref}"
+            if [ "${REF_TYPE}" = "tag" ]; then
+              echo "${REGISTRY}/${IMAGE_NAME}:${version}"
+              if [ "$prerelease" = "false" ]; then
+                echo "${REGISTRY}/${IMAGE_NAME}:latest"
+              fi
+            fi
+            echo "_EOF_"
+            echo "version=${version}"
+          } >> "$GITHUB_OUTPUT"
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+
+  sign:
+    needs: build
+    runs-on: ubuntu-latest
+    permissions:
+      id-token: write
+      contents: read
+      packages: write
+
+    steps:
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Install Cosign
+        uses: sigstore/cosign-installer@v3
+
+      - name: Sign images
+        env:
+          TAGS: ${{ needs.build.outputs.tags }}
+        run: |
+          printf '%s\n' "$TAGS" | while IFS= read -r tag; do
+            [ -n "${tag}" ] || continue
+            cosign sign --yes --recursive "${tag}"
+          done
+
+  provenance:
+    needs: [build, sign]
+    runs-on: ubuntu-latest
+    permissions:
+      id-token: write
+      contents: read
+      packages: write
+
+    steps:
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Install Cosign
+        uses: sigstore/cosign-installer@v3
+
+      - name: Generate SLSA provenance predicate
+        run: |
+          started_on="$(date -u +%Y-%m-%dT%H:%M:%SZ)"
+          predicate_file="${RUNNER_TEMP}/slsa-provenance.json"
+          cat > "${predicate_file}" <<JSON
+          {
+            "buildDefinition": {
+              "buildType": "https://github.com/${GITHUB_REPOSITORY}/.github/workflows/container.yml@${GITHUB_REF}",
+              "externalParameters": {},
+              "internalParameters": {},
+              "resolvedDependencies": []
+            },
+            "runDetails": {
+              "builder": {
+                "id": "https://github.com/${GITHUB_REPOSITORY}/actions/runs/${GITHUB_RUN_ID}"
+              },
+              "metadata": {
+                "invocationId": "${GITHUB_RUN_ID}",
+                "startedOn": "${started_on}"
+              },
+              "byproducts": []
+            }
+          }
+          JSON
+
+      - name: Attach SLSA provenance
+        env:
+          TAGS: ${{ needs.build.outputs.tags }}
+        run: |
+          printf '%s\n' "$TAGS" | while IFS= read -r tag; do
+            [ -n "${tag}" ] || continue
+            cosign attest --yes \
+              --predicate "${RUNNER_TEMP}/slsa-provenance.json" \
+              --type=slsaprovenance1 \
+              "${tag}"
+          done
+
+  verify:
+    needs: [sign, provenance]
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: read
+
+    steps:
+      - name: Log in to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Install Cosign
+        uses: sigstore/cosign-installer@v3
+
+      - name: Verify signatures
+        env:
+          TAGS: ${{ needs.build.outputs.tags }}
+          REPO: ${{ github.repository }}
+        run: |
+          printf '%s\n' "$TAGS" | while IFS= read -r tag; do
+            [ -n "${tag}" ] || continue
+            cosign verify \
+              --certificate-identity="https://github.com/${REPO}/.github/workflows/container.yml@${GITHUB_REF}" \
+              --certificate-oidc-issuer="https://token.actions.githubusercontent.com" \
+              "${tag}"
+          done