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

| Parameter | Type | Required | Default | Description | |-----------|------|----------|---------|-------------| | registry_type | enum | No | docker | docker/ecr/gcr/acr | | auth | boolean | No | true | Enable authentication | | tls | boolean | No | true | Enable TLS |

Registry Types

| Registry | Provider | Auth Method | |----------|----------|-------------| | Docker Hub | Docker | Username/token | | GHCR | GitHub | GitHub token | | ECR | AWS | IAM/CLI | | GCR | Google | Service account | | ACR | Azure | Service principal |

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

| Error | Cause | Solution | |-------|-------|----------| | unauthorized | Bad credentials | Re-login | | manifest unknown | Image not found | Check name/tag | | denied: access | No permission | Check IAM/roles | | TLS handshake | Certificate issue | Add to trusted certs |

Fallback Strategy

Verify credentials: docker login
Check image exists in registry
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