Scanning Containers with Trivy in CI/CD

When to Use

• When building Docker container images in CI/CD and needing automated vulnerability scanning before registry push
• When establishing quality gates that prevent images with critical or high CVEs from reaching production
• When compliance requirements mandate vulnerability scanning of all container images before deployment
• When scanning IaC files (Dockerfiles, Kubernetes manifests) alongside container image scanning
• When needing a single tool to scan OS packages, language-specific dependencies, and misconfigurations

Do not use for runtime container security monitoring (use Falco), for scanning running containers in production (use runtime agents), or when only scanning application source code without containerization (use SAST tools).

Prerequisites

• Trivy CLI installed (v0.50+) or access to aquasecurity/trivy-action GitHub Action
• Docker daemon available in CI/CD for building and scanning images
• Container registry credentials for pulling base images and pushing scanned images
• Trivy vulnerability database accessible (downloaded automatically or cached)

Workflow

Step 1: Configure Trivy Scanning in GitHub Actions

Set up a GitHub Actions workflow that builds a Docker image and scans it with Trivy before pushing to a container registry.

# .github/workflows/container-security.yml
name: Container Security Scan

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]
    paths:
      - 'Dockerfile'
      - 'docker-compose*.yml'
      - 'src/**'
      - 'requirements*.txt'
      - 'package*.json'

jobs:
  build-and-scan:
    runs-on: ubuntu-latest
    permissions:
      security-events: write
      contents: read

    steps:
      - uses: actions/checkout@v4

      - name: Build Docker image
        run: docker build -t app:${{ github.sha }} .

      - name: Run Trivy vulnerability scanner
        uses: aquasecurity/trivy-action@0.28.0
        with:
          image-ref: 'app:${{ github.sha }}'
          format: 'sarif'
          output: 'trivy-results.sarif'
          severity: 'CRITICAL,HIGH'
          exit-code: '1'
          ignore-unfixed: true

      - name: Upload Trivy scan results
        uses: github/codeql-action/upload-sarif@v3
        if: always()
        with:
          sarif_file: 'trivy-results.sarif'
          category: 'trivy-container'

      - name: Run Trivy misconfiguration scanner
        uses: aquasecurity/trivy-action@0.28.0
        with:
          scan-type: 'config'
          scan-ref: '.'
          format: 'table'
          exit-code: '1'
          severity: 'CRITICAL,HIGH'

Step 2: Scan Dockerfiles for Misconfigurations

Trivy detects common Dockerfile security issues such as running as root, using latest tags, and exposing unnecessary ports.

# Scan Dockerfile for misconfigurations
trivy config --severity HIGH,CRITICAL ./Dockerfile

# Scan with custom policy directory
trivy config --policy ./security-policies --severity MEDIUM,HIGH,CRITICAL .

# Example secure Dockerfile practices Trivy checks for:
# - USER instruction present (not running as root)
# - HEALTHCHECK instruction defined
# - Base image uses specific tag, not :latest
# - No secrets in ENV or ARG instructions
# - COPY preferred over ADD

Step 3: Integrate with GitLab CI/CD

# .gitlab-ci.yml
stages:
  - build
  - scan
  - push

variables:
  TRIVY_CACHE_DIR: .trivycache/

build:
  stage: build
  script:
    - docker build -t $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA .
    - docker save $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA -o image.tar
  artifacts:
    paths:
      - image.tar

trivy-scan:
  stage: scan
  image:
    name: aquasec/trivy:latest
    entrypoint: [""]
  cache:
    paths:
      - .trivycache/
  script:
    - trivy image
        --input image.tar
        --exit-code 1
        --severity CRITICAL,HIGH
        --ignore-unfixed
        --format json
        --output trivy-report.json
    - trivy image
        --input image.tar
        --severity CRITICAL,HIGH,MEDIUM
        --format table
  artifacts:
    reports:
      container_scanning: trivy-report.json
    paths:
      - trivy-report.json
  allow_failure: false

push:
  stage: push
  needs: [trivy-scan]
  script:
    - docker load -i image.tar
    - docker push $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA

Step 4: Configure Trivy Ignore and Exception Handling

Manage false positives and accepted risks through Trivy's ignore file and VEX statements.

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