You can see the hands-on video here: https://blog.sofianeouafir.com/docker/video-hands-on-introduction-to-docker-stack Introduction to Docker Stack Docker Stack is an essential tool for managing Docker services across multiple nodes in a Docker Swarm using a docker-compose.yml file. In this tutorial, I dive into Docker Stack’s deployment capabilities and the secure management of secrets, using a practical example involving Drupal and PostgreSQL. Docker-Compose File Setup Here’s our docker-compose.yml file that sets up the Drupal and PostgreSQL services: version: '3.8' services: drupal: image: drupal:8.2 ports: - "8080:80" deploy: replicas: 2 update_config: parallelism: 2 delay: 10s restart_policy: condition: on-failure postgres: image: postgres:14 secrets: - psql-pw environment: POSTGRES_PASSWORD_FILE: /run/secrets/psql-pw POSTGRES_DB: drupal POSTGRES_USER: user deploy: placement: constraints: [node.role == manager] secrets: psql-pw: external: true Understanding the Deploy Section The deploy section of the Docker Compose file specifies deployment strategies in a swarm environment, including: Replicas: Defines the number of instances for the service.
Update_config:
Parallelism: Sets how many service tasks are updated simultaneously.
Delay: Adds a delay between updates to different service tasks to ensure smooth roll-outs.
Restart_policy:
Condition: Determines under what conditions the service should be restarted. Managing Secrets in Docker Stack What is a Docker Secret? A Docker secret securely stores and manages sensitive data within Docker services, encrypted during transit and at rest, and only accessible by specifically authorized services. Managing Secrets with Docker Stack Secrets can be managed in Docker Stack in two ways: Using Secret Files: Ideal for development, storing sensitive data in local files securely transferred into Docker Swarm during deployment.
secrets: psql-pw: file: ./your-file.txt
External Secrets: For production, secrets are created directly in Docker using the CLI, avoiding the storage of sensitive information in files.
secrets: psql-pw: external: true Hands-On: Deploying the Stack in Docker Swarm To deploy your stack in Docker Swarm, follow these steps: Step 1: Prepare Your Docker Environment Ensure Docker is running and connected to your Docker Swarm. Refer to this guide for setting up a 3-node Docker Swarm. Step 2: Create and Edit the docker-compose.yml File On your swarm node, initialize and edit the docker-compose file to inclue our own docker-compose file: touch docker-compose.yml; vim docker-compose.yml; Step 3: Create the Secret echo "myverysecretpassword" | docker secret create psql-pw - Step 4: Deploy the Stack docker stack deploy -c docker-compose.yml demo-stack Step 5: Verify the Deployment List Services: docker stack services demo-stack
List Tasks: docker stack ps demo-stack Step 6: View the Secrets in the Container Get inside the container docker exec -it [container-name] bash See the secret values cat /run/secrets/psql-pw Step 7: View Logs and Debug docker service logs drupal
docker service logs postgres Step 8: Play with your configs For example, you can scale up and down your services by editing the replicas values in your docker-compose file and re-deploy using the same deploy command. Step 9: Play with your Drupal app! Your drupal application should now be up and running on port 8080! Conclusion You have successfully configured a robust Docker Swarm with three nodes. This setup is now running efficient instances of Drupal and PostgreSQL, demonstrating Docker Stack’s powerful capabilities for real-world applications. Happy deploying! You can see the hands-on video here: https://blog.sofianeouafir.com/docker/video-hands-on-introduction-to-docker-stack https://blog.sofianeouafir.com/docker/video-hands-on-introduction-to-docker-stack Introduction to Docker Stack Docker Stack is an essential tool for managing Docker services across multiple nodes in a Docker Swarm using a docker-compose.yml file . In this tutorial, I dive into Docker Stack’s deployment capabilities and the secure management of secrets, using a practical example involving Drupal and PostgreSQL. using a docker-compose.yml file Docker-Compose File Setup Here’s our docker-compose.yml file that sets up the Drupal and PostgreSQL services: docker-compose.yml version: '3.8' services: drupal: image: drupal:8.2 ports: - "8080:80" deploy: replicas: 2 update_config: parallelism: 2 delay: 10s restart_policy: condition: on-failure version: '3.8' services: drupal: image: drupal:8.2 ports: - "8080:80" deploy: replicas: 2 update_config: parallelism: 2 delay: 10s restart_policy: condition: on-failure postgres: image: postgres:14 secrets: - psql-pw environment: POSTGRES_PASSWORD_FILE: /run/secrets/psql-pw POSTGRES_DB: drupal POSTGRES_USER: user deploy: placement: constraints: [node.role == manager] postgres: image: postgres:14 secrets: - psql-pw environment: POSTGRES_PASSWORD_FILE: /run/secrets/psql-pw POSTGRES_DB: drupal POSTGRES_USER: user deploy: placement: constraints: [node.role == manager] secrets: psql-pw: external: true secrets: psql-pw: external: true Understanding the Deploy Section The deploy section of the Docker Compose file specifies deployment strategies in a swarm environment, including: deploy Replicas: Defines the number of instances for the service. Update_config: Parallelism: Sets how many service tasks are updated simultaneously. Delay: Adds a delay between updates to different service tasks to ensure smooth roll-outs. Restart_policy: Condition: Determines under what conditions the service should be restarted. Replicas : Defines the number of instances for the service. Replicas Update_config : Update_config Parallelism : Sets how many service tasks are updated simultaneously. Parallelism Delay : Adds a delay between updates to different service tasks to ensure smooth roll-outs. Delay Restart_policy : Restart_policy Condition : Determines under what conditions the service should be restarted. Condition Managing Secrets in Docker Stack What is a Docker Secret? A Docker secret securely stores and manages sensitive data within Docker services, encrypted during transit and at rest, and only accessible by specifically authorized services. Managing Secrets with Docker Stack Secrets can be managed in Docker Stack in two ways: Using Secret Files: Ideal for development, storing sensitive data in local files securely transferred into Docker Swarm during deployment. secrets: psql-pw: file: ./your-file.txt External Secrets: For production, secrets are created directly in Docker using the CLI, avoiding the storage of sensitive information in files. secrets: psql-pw: external: true Using Secret Files : Ideal for development, storing sensitive data in local files securely transferred into Docker Swarm during deployment. Using Secret Files secrets: psql-pw: file: ./your-file.txt External Secrets : For production, secrets are created directly in Docker using the CLI, avoiding the storage of sensitive information in files. External Secrets secrets: psql-pw: external: true Hands-On: Deploying the Stack in Docker Swarm To deploy your stack in Docker Swarm, follow these steps: Step 1: Prepare Your Docker Environment Ensure Docker is running and connected to your Docker Swarm. Refer to this guide for setting up a 3-node Docker Swarm. this guide Step 2: Create and Edit the docker-compose.yml File On your swarm node, initialize and edit the docker-compose file to inclue our own docker-compose file: touch docker-compose.yml; vim docker-compose.yml; Step 3: Create the Secret echo "myverysecretpassword" | docker secret create psql-pw - Step 4: Deploy the Stack docker stack deploy -c docker-compose.yml demo-stack Step 5: Verify the Deployment List Services: docker stack services demo-stack List Tasks: docker stack ps demo-stack List Services : docker stack services demo-stack List Services docker stack services demo-stack List Tasks : docker stack ps demo-stack List Tasks docker stack ps demo-stack Step 6: View the Secrets in the Container Get inside the container docker exec -it [container-name] bash See the secret values cat /run/secrets/psql-pw Step 7: View Logs and Debug docker service logs drupal
docker service logs postgres Step 8: Play with your configs For example, you can scale up and down your services by editing the replicas values in your docker-compose file and re-deploy using the same deploy command. Step 9: Play with your Drupal app! Your drupal application should now be up and running on port 8080! Conclusion You have successfully configured a robust Docker Swarm with three nodes. This setup is now running efficient instances of Drupal and PostgreSQL, demonstrating Docker Stack’s powerful capabilities for real-world applications. Happy deploying!

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