[patch] Harden verified image publication

.github/workflows/build-push.yml

@@ -1,8 +1,16 @@
 name: build-push
 on:
+  pull_request:
   push:
+    branches:
+      - main
+    tags:
+      - "*"
   workflow_dispatch:
 
+permissions:
+  contents: read
+
 jobs:
   lint-test:
     runs-on: ubuntu-24.04
@@ -46,10 +54,66 @@ jobs:
         env:
           CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
 
+  image-check:
+    if: github.event_name == 'pull_request'
+    strategy:
+      fail-fast: false
+      matrix:
+        architecture:
+          - runner: ubuntu-24.04
+            platform: linux/amd64
+            suffix: amd64
+          - runner: ubuntu-24.04-arm
+            platform: linux/arm64
+            suffix: arm64
+    runs-on: ${{ matrix.architecture.runner }}
+    steps:
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6
+        with:
+          persist-credentials: false
+
+      - uses: docker/setup-buildx-action@e468171a9de216ec08956ac3ada2f0791b6bd435 # v3
+
+      - name: Build native image without credentials
+        uses: docker/build-push-action@263435318d21b8e681c14492fe198d362a7d2c83 # v6
+        with:
+          context: .
+          load: true
+          platforms: ${{ matrix.architecture.platform }}
+          provenance: false
+          push: false
+          tags: cap:ci-${{ matrix.architecture.suffix }}
+
+      - name: Scan native image
+        uses: aquasecurity/trivy-action@ed142fd0673e97e23eac54620cfb913e5ce36c25 # v0.36.0
+        with:
+          image-ref: cap:ci-${{ matrix.architecture.suffix }}
+          format: table
+          exit-code: "1"
+          ignore-unfixed: true
+          severity: HIGH,CRITICAL
+          vuln-type: os,library
+
   run:
+    name: run
+    if: ${{ always() && github.event_name == 'pull_request' }}
+    needs: [lint-test, image-check]
+    permissions: {}
+    uses: libops/.github/.github/workflows/pr-status.yaml@057262171193c6d563e7b08ae93d0c4aebfce2bd # credential-free-required-status
+    with:
+      needs-json: ${{ toJSON(needs) }}
+
+  publish:
+    if: github.ref == 'refs/heads/main' || (github.event_name == 'push' && startsWith(github.ref, 'refs/tags/'))
     needs: [lint-test]
-    uses: libops/.github/.github/workflows/build-push.yaml@main
+    uses: libops/.github/.github/workflows/build-push.yaml@a86300fb8020d0f7141bb9f833d89b5dbd7aa4d7 # guarded-signed-image-publisher
+    with:
+      ref: ${{ github.sha }}
+      expected-main-sha: ${{ github.ref == 'refs/heads/main' && github.sha || '' }}
+      scan: true
+      sign: true
+      certificate-identity: https://github.com/libops/.github/.github/workflows/build-push.yaml@a86300fb8020d0f7141bb9f833d89b5dbd7aa4d7
     permissions:
       contents: read
       packages: write
-    secrets: inherit
+      id-token: write

.trivyignore

@@ -0,0 +1,4 @@
+# Cap links the Prometheus parser/export client, not Prometheus's remote-read
+# HTTP handler where this decompression issue exists. Remove this exception
+# when prometheus-engine exposes a supported exporter on the patched line.
+CVE-2026-42154 exp:2026-10-01

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.26.3-alpine3.22@sha256:be93003ee861b3b91b6ebcb22678524947e0cd786c2df3f32af520006b1e54f5 AS builder
+FROM golang:1.25.12-alpine@sha256:56961d79ea8129efddcc0b8643fd8a5416b4e6228cfd477e3fd61deb2672c587 AS builder
 
 SHELL ["/bin/ash", "-o", "pipefail", "-ex", "-c"]
 
@@ -15,7 +15,9 @@ COPY scraper ./scraper
 RUN --mount=type=cache,target=/root/.cache/go-build \
   CGO_ENABLED=0 go build -ldflags="-s -w" -o /app/binary .
 
-FROM golang:1.26.3-alpine3.22@sha256:be93003ee861b3b91b6ebcb22678524947e0cd786c2df3f32af520006b1e54f5
+FROM alpine:3.24@sha256:28bd5fe8b56d1bd048e5babf5b10710ebe0bae67db86916198a6eec434943f8b
+
+RUN apk add --no-cache ca-certificates
 
 COPY --from=builder /app/binary /app/binary
 

ci/workflow_contract_test.go

@@ -0,0 +1,69 @@
+package ci
+
+import (
+	"os"
+	"strings"
+	"testing"
+)
+
+const sharedPublisherSHA = "a86300fb8020d0f7141bb9f833d89b5dbd7aa4d7"
+
+func TestImagePublicationWorkflowContract(t *testing.T) {
+	workflow, err := os.ReadFile("../.github/workflows/build-push.yml")
+	if err != nil {
+		t.Fatal(err)
+	}
+	contents := string(workflow)
+
+	required := []string{
+		"pull_request:",
+		"if: github.event_name == 'pull_request'",
+		"if: github.ref == 'refs/heads/main' || (github.event_name == 'push' && startsWith(github.ref, 'refs/tags/'))",
+		"Build native image without credentials",
+		"libops/.github/.github/workflows/build-push.yaml@" + sharedPublisherSHA,
+		"ref: ${{ github.sha }}",
+		"expected-main-sha: ${{ github.ref == 'refs/heads/main' && github.sha || '' }}",
+		"scan: true",
+		"sign: true",
+		"certificate-identity: https://github.com/libops/.github/.github/workflows/build-push.yaml@" + sharedPublisherSHA,
+		"packages: write",
+		"id-token: write",
+	}
+	for _, value := range required {
+		if !strings.Contains(contents, value) {
+			t.Errorf("image workflow must contain %q", value)
+		}
+	}
+
+	forbidden := []string{
+		"build-push.yaml@main",
+		"build-push-ghcr.yaml",
+		"secrets: inherit",
+		"docker-registry:",
+		"additional-gar-registry:",
+	}
+	for _, value := range forbidden {
+		if strings.Contains(contents, value) {
+			t.Errorf("image workflow must not contain %q", value)
+		}
+	}
+}
+
+func TestTrivyExceptionIsNarrowAndExpiring(t *testing.T) {
+	ignore, err := os.ReadFile("../.trivyignore")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	lines := strings.Split(strings.TrimSpace(string(ignore)), "\n")
+	var rules []string
+	for _, line := range lines {
+		line = strings.TrimSpace(line)
+		if line != "" && !strings.HasPrefix(line, "#") {
+			rules = append(rules, line)
+		}
+	}
+	if len(rules) != 1 || rules[0] != "CVE-2026-42154 exp:2026-10-01" {
+		t.Fatalf("unexpected Trivy exception rules: %q", rules)
+	}
+}