Add Trivy Scan and Structure Test (#71)

* Add Trivy Scan and Structure Tests
* Update README, fancy new Badges!
* Update Makefile, full-qualified Image names

.github/workflows/test-lts-container-images.yaml

@@ -0,0 +1,49 @@
+name: Test LTS Container Images
+
+on: [push, pull_request]
+
+jobs:
+  test_images:
+    name: Test LTS Container Images with Trivy
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        context:
+          - apache
+          - fpm-alpine
+          - fpm
+    steps:
+      - name: 'Check out the repo'
+        uses: actions/checkout@v2
+
+      - name: 'Set up Docker Buildx'
+        uses: docker/setup-buildx-action@v1
+
+      - name: 'Build Container images'
+        uses: docker/build-push-action@v2
+        with:
+          context: 3.0/${{ matrix.context }}
+          push: false
+          load: true
+          tags: docker.io/martialblog/limesurvey:3-${{ matrix.context }}
+
+      - name: 'Run Structure tests'
+        uses: plexsystems/container-structure-test-action@v0.2.0
+        with:
+          image: docker.io/martialblog/limesurvey:3-${{ matrix.context }}
+          config: tests/${{ matrix.context }}-tests.yaml
+
+      - name: 'Run vulnerability scanner'
+        uses: aquasecurity/trivy-action@master
+        with:
+          image-ref: docker.io/martialblog/limesurvey:3-${{ matrix.context }}
+          format: 'template'
+          template: '@/contrib/sarif.tpl'
+          output: trivy-results-3-${{ matrix.context }}.sarif
+          severity: 'CRITICAL,HIGH'
+
+      - name: 'Upload Trivy scan results to GitHub'
+        uses: github/codeql-action/upload-sarif@v1
+        with:
+          sarif_file: trivy-results-3-${{ matrix.context }}.sarif
+          category: "${{ matrix.context }}"