feat: add trivy scanning (#581)

.github/workflows/trivy.yml

@@ -0,0 +1,37 @@
+name: trivy
+on:
+  schedule:
+    - cron: "00 8 * * *" # build at 8:00 UTC every day 
+                         # 120 minutes after secureblue images start building
+  push:
+    branches:
+      - live
+
+  workflow_dispatch: # allow manually triggering builds
+jobs:
+  build:
+    name: Trivy
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      - name: Run Trivy vulnerability scanner
+        uses: aquasecurity/trivy-action@915b19bbe73b92a6cf82a1bc12b087c9a19a5fe2 # v0.28.0
+        with:
+          image-ref: 'ghcr.io/secureblue/silverblue-main-userns-hardened:latest'
+          format: template
+          template: '@/contrib/sarif.tpl'
+          output: trivy-results.sarif
+          timeout: 30m0s
+          skip-dirs: "/sysroot/ostree"
+        env:
+          TRIVY_DB_REPOSITORY: ghcr.io/aquasecurity/trivy-db,public.ecr.aws/aquasecurity/trivy-db
+          TRIVY_JAVA_DB_REPOSITORY: ghcr.io/aquasecurity/trivy-java-db,public.ecr.aws/aquasecurity/trivy-java-db
+      - name: Upload Trivy scan results to GitHub Security tab
+        uses: github/codeql-action/upload-sarif@4f3212b61783c3c68e8309a0f18a699764811cda # v3.27.1
+        with:
+          sarif_file: trivy-results.sarif
+      - uses: actions/upload-artifact@b4b15b8c7c6ac21ea08fcf65892d2ee8f75cf882 # v4.4.3
+        with:
+          name: Trivy scan SARIF
+          path: trivy-results.sarif