github action + minor refactor

.github/workflows/image-scanner.yml

@@ -0,0 +1,31 @@
+name: build
+on:
+  workflow_run:
+    workflows: [ "Code check" ]
+    types:
+      - completed
+jobs:
+  on-failure:
+    runs-on: ubuntu-latest
+    if: ${{ github.event.workflow_run.conclusion == 'failure' }}
+    steps:
+      - run: echo 'The triggering workflow failed'
+  build:
+    name: Image vulnerability scanner
+    if: ${{ github.event.workflow_run.conclusion == 'success' }}
+    runs-on: ubuntu-20.04
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - name: Build an image from Dockerfile
+        run: |
+          docker build -t docker.io/my-organization/my-app:${{ github.sha }} .
+      - name: Run Trivy vulnerability scanner
+        uses: aquasecurity/trivy-action@master
+        with:
+          image-ref: 'docker.io/my-organization/my-app:${{ github.sha }}'
+          format: 'table'
+          exit-code: '1'
+          ignore-unfixed: true
+          vuln-type: 'os,library'
+          severity: 'CRITICAL,HIGH'