Practical Docker Commands in CI/CD
Here are practical examples of the Docker commands, incorporating best practices for CI/CD workflows:
1. Docker Build and Push (73 instances):
- name: Build and Push Image
run: |
docker build -t registry.example.com/my-project/my-app:${{ github.sha }} .
docker push registry.example.com/my-project/my-app:${{ github.sha }}
This builds an image tagged with the GitHub commit SHA for traceability and pushes it to a registry.Reason why you would watch this command is because when you push something to a registry and it's a new version for example, you have to tag the image and when you tag it and you push it then it pushes that tag and that and subsequently that docker image to the registry. So for example if you building some docker images inside of your continuous integration pipeline, you would tag the image and then push it.This also be useful for deployment for example. Echo command in this case is used to pass the password that's associated with your registry to the standard input of the docker command, and this way it makes it so that it's not it doesn't get displayed on the output, and also you're not creating these temporary files that have passwords in them, so it's only done in memory.
2. Docker Login and Logout (13 instances):
- name: Docker Login
run: echo "${{ secrets.DOCKER_PASSWORD }}" | docker login -u ${{ secrets.DOCKER_USERNAME }} --password-stdin registry.example.com
- name: Docker Logout
if: always()
run: docker logout registry.example.com
This securely logs into the registry using secrets, and the if: always() ensures logout even if previous steps fail.
3. Docker Run (8 instances):
- name: Run Database
run: docker run -d -p 5432:5432 --name my-postgres -e POSTGRES_PASSWORD=secret postgres:13
This starts a PostgreSQL database container in detached mode with specific configurations.
4. Docker Pull (4 instances):
- name: Pull Node.js Image
run: docker pull node:16-alpine
This pulls a specific Node.js image for use in later steps.
5. Docker RMI (Remove Image) (3 instances):
- name: Clean Up Images
if: always()
run: docker rmi $(docker images -f "dangling=true" -q)
This cleans up dangling images after builds, freeing up space.
6. Docker Start & Exec & Network Ops (4 instances):
- name: Start Database
run: docker start my-postgres
- name: Execute Command in Container
run: docker exec my-postgres psql -U postgres -c "SELECT version();"
- name: Create Network
run: docker network create my-network
This demonstrates starting a container, running commands inside it, and managing networks.
7. Docker Tag (2 instances):
- name: Tag Image for Production
run: docker tag registry.example.com/my-project/my-app:${{ github.sha }} registry.example.com/my-project/my-app:production
This creates a production tag for the latest successful build.
8. Docker System and Info (2 instances):
- name: System Prune
if: always()
run: docker system prune -f
- name: Docker Info
run: docker info
This cleans up unused Docker resources and displays system-wide information.
9. Docker-compose (1 instance):
- name: Build and Push with Compose
run: |
docker-compose -f docker-compose.prod.yml build
docker-compose -f docker-compose.prod.yml push
This builds and pushes a multi-container application using docker-compose.
10. Docker CP (Copy) (1 instance):
- name: Copy File to Container
run: docker cp ./config.json my-container:/app/config.json
This copies a configuration file to a running container.
11. Docker Commit (1 instance):
- name: Commit Container Changes
run: docker commit my-container registry.example.com/my-project/modified-container:latest
This creates a new image based on the changes made to a container.
12. Docker Inspect imagetools (1 instance):
- name: Inspect Image
run: docker buildx imagetools inspect registry.example.com/my-project/my-app:latest
This provides details about the specified image.
13. Docker Run Test (1 instance):
- name: Run Tests in Container
run: docker run my-test-image npm test
This executes tests inside a container dedicated to testing.
14. Docker Pull and Run (1 instance):
- name: Pull and Run Migration Script
run: |
docker pull registry.example.com/my-project/migration-tool:latest
docker run registry.example.com/my-project/migration-tool:latest --database my-database
This pulls a dedicated image and then runs a migration script with it.