Working with Docker Images¶

Push and pull Docker images to/from TUKE Harbor Repository.

Push

Upload images to repository.
Pull

Download images from repository.
Tagging

Proper version labeling.
CI/CD

Pipeline automation.

Basic Workflow¶

graph LR
    A[Build] --> B[Tag]
    B --> C[Login]
    C --> D[Push]
    D --> E[Pull]

Step	Command	Description
1	`docker build`	Create image
2	`docker tag`	Label for repository
3	`docker login`	Login
4	`docker push`	Upload to repository
5	`docker pull`	Download from repository

Creating a Docker Image¶

From Dockerfile¶

FROM python:3.11-slim
WORKDIR /app
COPY app.py .
CMD ["python", "app.py"]

docker build -t my-application:v1.0 .

From running container¶

docker commit <container-id> my-application:v1.0

Tag and Push¶

Tag the image¶

docker tag my-application:v1.0 repository.cloud.tuke.sk/my-project/my-application:v1.0

Format

repository.cloud.tuke.sk/<project>/<image-name>:<tag>

Parameter	Description	Example
project	Project name in Harbor	`my-project`
image-name	Docker image name	`my-application`
tag	Version or label	`v1.0`, `latest`, `dev`

Log in¶

docker login repository.cloud.tuke.sk

Push image¶

docker push repository.cloud.tuke.sk/my-project/my-application:v1.0

Successful upload

The push refers to repository [repository.cloud.tuke.sk/my-project/my-application]
v1.0: digest: sha256:abc123... size: 1234

Pull and Run¶

Pull image¶

docker pull repository.cloud.tuke.sk/my-project/my-application:v1.0

Run container¶

docker run -d repository.cloud.tuke.sk/my-project/my-application:v1.0

Advanced Usage¶

Multi-platform images¶

Build for multiple architectures (amd64, arm64):

# Create buildx builder
docker buildx create --name multiarch --use

# Build and push for multiple platforms
docker buildx build --platform linux/amd64,linux/arm64 \
  -t repository.cloud.tuke.sk/my-project/my-application:v1.0 \
  --push .

Multiple tags¶

# Tag image with multiple versions
docker tag my-application:v1.0 repository.cloud.tuke.sk/my-project/my-application:v1.0
docker tag my-application:v1.0 repository.cloud.tuke.sk/my-project/my-application:latest

# Push both versions
docker push repository.cloud.tuke.sk/my-project/my-application:v1.0
docker push repository.cloud.tuke.sk/my-project/my-application:latest

Multi-stage build (size optimization)¶

FROM golang:1.21 AS builder
WORKDIR /app
COPY . .
RUN go build -o app

FROM alpine:latest
COPY --from=builder /app/app /app
CMD ["/app"]

Docker Compose¶

docker-compose.yml¶

version: '3.8'

services:
  app:
    image: repository.cloud.tuke.sk/my-project/my-application:v1.0
    ports:
      - "8080:80"
    restart: unless-stopped

Running¶

docker login repository.cloud.tuke.sk
docker-compose pull
docker-compose up -d

Kubernetes¶

Create docker-registry secret¶

kubectl create secret docker-registry tuke-registry \
  --docker-server=repository.cloud.tuke.sk \
  --docker-username=ab123cd \
  --docker-password=your-password \
  --docker-email=ab123cd@tuke.sk

Deployment YAML¶

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-application
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-application
  template:
    metadata:
      labels:
        app: my-application
    spec:
      imagePullSecrets:
      - name: tuke-registry
      containers:
      - name: app
        image: repository.cloud.tuke.sk/my-project/my-application:v1.0
        ports:
        - containerPort: 80

CI/CD Integration¶

GitLab CI/CD¶

# .gitlab-ci.yml
variables:
  IMAGE_NAME: repository.cloud.tuke.sk/$CI_PROJECT_PATH:$CI_COMMIT_SHORT_SHA

build:
  stage: build
  image: docker:latest
  services:
    - docker:dind
  before_script:
    - docker login -u $HARBOR_USER -p $HARBOR_PASSWORD repository.cloud.tuke.sk
  script:
    - docker build -t $IMAGE_NAME .
    - docker push $IMAGE_NAME

GitHub Actions¶

# .github/workflows/docker.yml
name: Build and Push Docker Image

on:
  push:
    branches: [ main ]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3

      - name: Login to TUKE Harbor
        uses: docker/login-action@v2
        with:
          registry: repository.cloud.tuke.sk
          username: ${{ secrets.HARBOR_USERNAME }}
          password: ${{ secrets.HARBOR_PASSWORD }}

      - name: Build and push
        uses: docker/build-push-action@v4
        with:
          push: true
          tags: repository.cloud.tuke.sk/my-project/my-application:${{ github.sha }}

Harbor Web UI¶

Viewing images¶

Log in to Harbor web UI
Go to your project
Click Repositories
Select repository and view all tags

Deleting an image¶

In the repository list, select a tag
Click Delete
Confirm deletion

Warning

Deleted images cannot be recovered!

Command Reference¶

# Login
docker login repository.cloud.tuke.sk

# Tag image
docker tag <local-image> repository.cloud.tuke.sk/<project>/<image>:<tag>

# Push image
docker push repository.cloud.tuke.sk/<project>/<image>:<tag>

# Pull image
docker pull repository.cloud.tuke.sk/<project>/<image>:<tag>

# List local images
docker images | grep repository.cloud.tuke.sk

# Logout
docker logout repository.cloud.tuke.sk

Best Practices¶

Versioning

Instead of latest, use specific versions: v1.0.0, 2024.1, git commit SHA.

Multi-stage builds

Use multi-stage builds to minimize image size.

Automation

Integrate build and push into CI/CD pipeline.

Documentation

Add README to images using LABEL in Dockerfile.

Security

Never store sensitive data (passwords, API keys) directly in Docker images!

Next Steps¶

Login

Logging in to repository.

Guide
FAQ

Common questions.

FAQ