Agent Skills: Docker CI/CD Skill

Docker CI/CD Skill

Integrate Docker with CI/CD pipelines for automated image builds, security scanning, and deployments.

Purpose

Set up automated Docker workflows with GitHub Actions, GitLab CI, and other CI/CD platforms.

Parameters

| Parameter | Type | Required | Default | Description | |-----------|------|----------|---------|-------------| | platform | enum | No | github | github/gitlab/jenkins | | registry | string | No | ghcr.io | Container registry | | scan | boolean | No | true | Include security scan |

GitHub Actions

Complete Workflow

name: Docker Build and Deploy

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

env:
  REGISTRY: ghcr.io
  IMAGE_NAME: ${{ github.repository }}

jobs:
  build:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write

    steps:
      - uses: actions/checkout@v4

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3

      - name: Login to Registry
        if: github.event_name != 'pull_request'
        uses: docker/login-action@v3
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Extract metadata
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          tags: |
            type=sha
            type=ref,event=branch
            type=semver,pattern={{version}}

      - name: Build and push
        uses: docker/build-push-action@v5
        with:
          context: .
          push: ${{ github.event_name != 'pull_request' }}
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          cache-from: type=gha
          cache-to: type=gha,mode=max

      - name: Scan for vulnerabilities
        uses: aquasecurity/trivy-action@master
        with:
          image-ref: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:sha-${{ github.sha }}
          exit-code: '1'
          severity: 'CRITICAL,HIGH'

Multi-Arch Build

- name: Set up QEMU
  uses: docker/setup-qemu-action@v3

- name: Build multi-arch
  uses: docker/build-push-action@v5
  with:
    platforms: linux/amd64,linux/arm64
    push: true
    tags: ${{ steps.meta.outputs.tags }}

GitLab CI

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

variables:
  DOCKER_IMAGE: $CI_REGISTRY_IMAGE:$CI_COMMIT_SHA

build:
  stage: build
  image: docker:24
  services:
    - docker:24-dind
  script:
    - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
    - docker build -t $DOCKER_IMAGE .
    - docker push $DOCKER_IMAGE

scan:
  stage: scan
  image:
    name: aquasec/trivy
    entrypoint: [""]
  script:
    - trivy image --exit-code 1 --severity CRITICAL $DOCKER_IMAGE

deploy:
  stage: deploy
  script:
    - ssh deploy@server "docker pull $DOCKER_IMAGE && docker compose up -d"
  only:
    - main

Best Practices

Caching

# GitHub Actions BuildKit cache
cache-from: type=gha
cache-to: type=gha,mode=max

# GitLab cache
cache:
  key: docker-$CI_COMMIT_REF_SLUG
  paths:
    - .docker-cache

Security

# Scan before push
- name: Scan
  run: trivy image --exit-code 1 --severity CRITICAL $IMAGE

# Sign images (cosign)
- name: Sign
  run: cosign sign $IMAGE

Error Handling

Common Errors

| Error | Cause | Solution | |-------|-------|----------| | unauthorized | Bad credentials | Check registry login | | rate limit | Docker Hub limits | Use authenticated pulls | | cache miss | First build | Cache will populate |

Fallback Strategy

1. Build without cache if cache corrupted
2. Use fallback registry if primary down
3. Deploy previous version on failure

Troubleshooting

Debug Checklist

• [ ] Registry credentials valid?
• [ ] Docker daemon running?
• [ ] Build context correct?
• [ ] Dockerfile present?

Usage

Skill("docker-ci-cd")

Assets

• assets/github-actions-docker.yaml - GitHub Actions template
• scripts/build-and-push.sh - Build script

Related Skills

• docker-production
• docker-security