Docker_registry

Chapter 09: Docker Registry

Docker Registry is a storage and distribution system for Docker images. This chapter covers using public and private registries.

What is a Registry?

┌─────────────────────────────────────────────────────────────────────────────┐
│                        Docker Registry Concept                               │
├─────────────────────────────────────────────────────────────────────────────┤
│                                                                             │
│   Registry                                                                  │
│   ┌─────────────────────────────────────────────────────────────────────┐   │
│   │                                                                     │   │
│   │  ┌─────────┐  ┌─────────┐  ┌─────────┐  ┌─────────┐            │   │
│   │  │ nginx   │  │ node    │  │ python  │  │ myapp   │            │   │
│   │  │ latest  │  │ 18-alpine│ │ 3.11   │  │ v1.0.0  │            │   │
│   │  └─────────┘  └─────────┘  └─────────┘  └─────────┘            │   │
│   │                                                                     │   │
│   └─────────────────────────────────────────────────────────────────────┘   │
│                                                                             │
│   Image Format: registry/namespace/repository:tag                           │
│                                                                             │
└─────────────────────────────────────────────────────────────────────────────┘

Types of Registries

1. Docker Hub (Public)

• Default public registry
• Free for public images
• Paid for private images

2. Docker Trusted Registry (DTR)

• Enterprise on-premise solution
• Part of Docker Enterprise

3. Cloud Registries

• Amazon ECR
• Google Container Registry (GCR)
• Azure Container Registry (ACR)
• GitHub Container Registry (GHCR)

4. Self-Hosted

• Harbor
• GitLab Container Registry
• Nexus Repository

Docker Hub

Using Docker Hub

# Search for images
docker search nginx

# Pull image
docker pull nginx

# Push to Docker Hub
docker tag myapp:latest username/myapp:latest
docker push username/myapp:latest

Docker Hub Features

• Public repositories (free)
• Automated builds
• Webhooks
• Organization teams

Amazon ECR

Setup ECR

# Login to ECR
aws ecr get-login-password --region us-east-1 | docker login --username AWS --password-stdin 123456789.dkr.ecr.us-east-1.amazonaws.com

# Pull image
docker pull 123456789.dkr.ecr.us-east-1.amazonaws.com/myapp:latest

# Push image
docker tag myapp:latest 123456789.dkr.ecr.us-east-1.amazonaws.com/myapp:latest
docker push 123456789.dkr.ecr.us-east-1.amazonaws.com/myapp:latest

ECR with Docker Compose

docker-compose.yml

services:
  app:
    image: 123456789.dkr.ecr.us-east-1.amazonaws.com/myapp:latest

Private Registry

Running a Local Registry

# Start registry
docker run -d -p 5000:5000 --name registry registry:2

# Tag image for local registry
docker tag myapp:latest localhost:5000/myapp:latest

# Push to local registry
docker push localhost:5000/myapp:latest

# Pull from local registry
docker pull localhost:5000/myapp:latest

Secure Registry with TLS

# Create certificates
mkdir -p certs
openssl req -newkey rsa:4096 -nodes -sha256 -keyout certs/domain.key -x509 -days 365 -out certs/domain.crt

# Start registry with TLS
docker run -d \
  --name registry \
  -p 5000:5000 \
  -v $(pwd)/certs:/certs \
  -e REGISTRY_HTTP_ADDR=0.0.0.0:5000 \
  -e REGISTRY_HTTP_TLS_CERTIFICATE=/certs/domain.crt \
  -e REGISTRY_HTTP_TLS_KEY=/certs/domain.key \
  registry:2

Harbor Registry

Installing Harbor

# Download Harbor installer
wget https://github.com/goharbor/harbor/releases/download/v2.9.0/harbor-offline-installer-v2.9.0.tgz

# Extract
tar xvf harbor-offline-installer-v2.9.0.tgz

# Configure
cp harbor.yml.tmpl harbor.yml
# Edit harbor.yml with your settings

# Install
./install.sh

Using Harbor

# Login
docker login harbor.example.com

# Tag image
docker tag myapp:latest harbor.example.com/myproject/myapp:latest

# Push
docker push harbor.example.com/myproject/myapp:latest

Registry Operations

Listing Images

# List all images in registry (using registry API)
curl -s https://registry.example.com/v2/_catalog | jq

# List image tags
curl -s https://registry.example.com/v2/myapp/tags/list | jq

Deleting Images

# Delete manifest (referenced by digest)
curl -X DELETE https://registry.example.com/v2/myapp/manifests/sha256:abc123...

# Run garbage collection
docker exec registry /bin/registry garbage-collect /etc/registry/config.yml

Authentication

Docker Login

# Login to Docker Hub
docker login

# Login to private registry
docker login registry.example.com

# Login with username
docker login -u username registry.example.com

Using .docker/config.json

{
  "auths": {
    "registry.example.com": {
      "auth": "base64-encoded-credentials"
    }
  }
}

Image Promotion

┌─────────────────────────────────────────────────────────────────────────────┐
│                      Image Promotion Pipeline                                │
├─────────────────────────────────────────────────────────────────────────────┤
│                                                                             │
│   Build → Dev Registry → Staging Registry → Production Registry           │
│                                                                             │
│   ┌─────────┐    ┌─────────┐    ┌─────────┐    ┌─────────────┐           │
│   │  Build  │───▶│  Dev    │───▶│ Staging │───▶│ Production  │           │
│   │  Server │    │ Registry │    │Registry │    │  Registry   │           │
│   └─────────┘    └─────────┘    └─────────┘    └─────────────┘           │
│                                                                             │
│   myapp:dev     myapp:staging    myapp:prod                            │
│                                                                             │
└─────────────────────────────────────────────────────────────────────────────┘

Summary

In this chapter, you learned:

• Docker registry concepts
• Using Docker Hub
• Amazon ECR setup and usage
• Running private registries
• Harbor registry
• Registry authentication and operations

Next Steps

• Chapter 10: Docker Best Practices