Multi-container scanning

Use multi-container scanning to scan multiple container images in a single pipeline. This feature enables you to:

• Scan multiple images in parallel.
• Configure scanning targets in a single configuration file.
• Integrate with existing container scanning workflows.

Multi-container scanning uses dynamic child pipelines to run scans concurrently, reducing overall pipeline execution time.

Supported images

Multi-container scanning supports:

• Images from public registries (Docker Hub, GitLab Container Registry, and others)
• Images from private registries (with authentication configured)
• Multi-architecture images

Enable multi-container scanning

Prerequisites:

• GitLab Runner with Docker executor.
• A .gitlab-multi-image.yml configuration file in your repository root.
• At least one container image to scan.

To enable multi-container scanning:

1. Create a .gitlab-multi-image.yml file in your repository root:

      scanTargets:
        - name: alpine
          tag: latest
        - name: python
          tag: 3.9-slim

2. Include the template in your .gitlab-ci.yml:

      include:
        - template: Jobs/Multi-Container-Scanning.latest.gitlab-ci.yml

3. Commit and push your changes. The pipeline runs the scans automatically.

Configuration

Configure multi-container scanning by editing the .gitlab-multi-image.yml file.

Basic configuration example

scanTargets:
  - name: alpine
    tag: "3.19"
  - name: ubuntu
    tag: "22.04"

Complete configuration example

# Include license information in reports
includeLicenses: true

# Configure registry authentication
auths:
  registry.example.com:
    username: ${REGISTRY_USER}
    password: ${REGISTRY_PASSWORD}

# Allow insecure connections (not recommended for production)
allowInsecure: false

# Additional CA certificates for custom registries
additionalCaCertificateBundle: |
  -----BEGIN CERTIFICATE-----
  ...
  -----END CERTIFICATE-----

# Images to scan
scanTargets:
  - name: registry.example.com/myapp
    tag: "v1.2.3"
  - name: postgres
    tag: "15-alpine"

Configuration options

Common scenarios

The following sections describe some example scenarios that you can adapt to suit your needs.

Scan images from different registries

scanTargets:
  - name: docker.io/library/nginx
    tag: "1.25"
  - name: registry.gitlab.com/mygroup/myapp
    tag: "main"
  - name: gcr.io/myproject/service
    tag: "prod"

Use private registry authentication

auths:
  registry.gitlab.com:
    username: ${CI_REGISTRY_USER}
    password: ${CI_REGISTRY_PASSWORD}
  docker.io:
    username: ${DOCKERHUB_USER}
    password: ${DOCKERHUB_TOKEN}

scanTargets:
  - name: registry.gitlab.com/private/image
    tag: latest

Scan specific versions for compliance

scanTargets:
  - name: postgres
    tag: "14.10"
  - name: redis
    tag: "7.2.3"
  - name: nginx
    tag: "1.25.3"

CI/CD variables

You can customize multi-container scanning behavior by using CI/CD variables.

Disable multi-container scanning

To disable scanning temporarily:

variables:
  CONTAINER_SCANNING_DISABLED: "true"

Disable MR pipeline scanning

variables:
  AST_ENABLE_MR_PIPELINES: "false"

View scan results

After the pipeline completes:

1. On the top bar, select Search or go to and find your project.
2. Go to your merge request or pipeline details page.
3. Select the Security tab.
4. View detected vulnerabilities from all scanned images.

Each scanned image generates:

• A container scanning report.
• A CycloneDX SBOM (Software Bill of Materials).
• License information (if includeLicenses: true).

Pipeline structure

Multi-container scanning creates two jobs:

• multi-cs::generate-scan: Generates the scanning configuration
• multi-cs::trigger-scan: Triggers a child pipeline with parallel scan jobs

The child pipeline contains one job per image in scanTargets.

Troubleshooting

When working with multi-container scanning, you might encounter the following issues.

Pipeline fails with “configuration file not found”

Cause: The .gitlab-multi-image.yml file is missing or in the wrong location.

Solution: Ensure .gitlab-multi-image.yml exists in your repository root.

Authentication fails for private registry

Cause: Invalid credentials or missing authentication configuration.

Solution:

1. Verify that credentials are correct and configured correctly.

      auths:
        registry.example.com:
          username: ${REGISTRY_USER}
          password: ${REGISTRY_PASSWORD}

2. Define variables in Settings > **CI/CD > Variables.

Scan takes too long

Cause: Multiple large images being scanned sequentially.

Solution: Multi-container scanning already runs scans in parallel.

Consider:

• Using smaller base images
• Scanning only specific image versions
• Adjusting GitLab Runner concurrency settings

Child pipeline doesn’t show reports

Cause: Missing strategy: mirror in trigger configuration.

Solution: This is configured by default in the template. If you’ve customized the template, ensure the trigger job includes strategy: mirror.