Docker Registry Skill

Set up and manage private Docker registries for secure image distribution and management.

Purpose

Deploy private registries, configure authentication, and manage images across multiple registries.

Parameters

Registry Types

Private Registry Setup

Docker Compose

services:
  registry:
    image: registry:2
    ports:
      - "5000:5000"
    volumes:
      - registry_data:/var/lib/registry
      - ./auth:/auth
      - ./certs:/certs
    environment:
      REGISTRY_AUTH: htpasswd
      REGISTRY_AUTH_HTPASSWD_REALM: Registry Realm
      REGISTRY_AUTH_HTPASSWD_PATH: /auth/htpasswd
      REGISTRY_HTTP_TLS_CERTIFICATE: /certs/domain.crt
      REGISTRY_HTTP_TLS_KEY: /certs/domain.key
    restart: unless-stopped

volumes:
  registry_data:

Create Auth File

# Create htpasswd file
docker run --rm --entrypoint htpasswd \
  httpd:alpine -Bbn admin password > auth/htpasswd

Registry Operations

Login

# Docker Hub
docker login

# GitHub Container Registry
echo $GITHUB_TOKEN | docker login ghcr.io -u USERNAME --password-stdin

# AWS ECR
aws ecr get-login-password | docker login --username AWS --password-stdin <account>.dkr.ecr.<region>.amazonaws.com

# Private registry
docker login registry.example.com

Push/Pull

# Tag for registry
docker tag myapp:latest registry.example.com/myapp:latest

# Push
docker push registry.example.com/myapp:latest

# Pull
docker pull registry.example.com/myapp:latest

Image Management

# List images in registry (API)
curl -X GET https://registry.example.com/v2/_catalog

# List tags
curl -X GET https://registry.example.com/v2/myapp/tags/list

# Delete image (via API)
curl -X DELETE https://registry.example.com/v2/myapp/manifests/<digest>

Multi-Registry Sync

# Copy between registries
skopeo copy \
  docker://source-registry/image:tag \
  docker://dest-registry/image:tag

# Sync all tags
skopeo sync --src docker --dest docker \
  source-registry/image dest-registry/

Cloud Registry Setup

AWS ECR

# Create repository
aws ecr create-repository --repository-name myapp

# Login
aws ecr get-login-password --region us-east-1 | \
  docker login --username AWS --password-stdin <account>.dkr.ecr.us-east-1.amazonaws.com

# Push
docker push <account>.dkr.ecr.us-east-1.amazonaws.com/myapp:latest

Google GCR

# Auth with service account
gcloud auth configure-docker

# Push
docker push gcr.io/project-id/myapp:latest

Error Handling

Common Errors

Fallback Strategy

1. Verify credentials: docker login
2. Check image exists in registry
3. Verify network connectivity

Troubleshooting

Debug Checklist

• Logged in? docker login
• Image tagged correctly?
• Registry accessible? curl https://registry/v2/
• TLS configured? Check certificates

Usage

Skill("docker-registry")

Assets

• assets/docker-compose-registry.yaml – Registry setup
• scripts/registry-setup.sh – Setup script

Related Skills

• docker-optimization
• docker-ci-cd