Replicación de Stacks con Docker Compose

How to get started with Docker Swarm and Docker Compose?

Getting started with Docker Swarm and Docker Compose may seem intimidating, but once you understand the basics, the benefits are clear. Docker Swarm gives you a lightweight solution for orchestrating containers, while Docker Compose makes it easy to manage services. An excellent starting point is to learn how to combine these technologies to maximize your application development capabilities.

How do I set up my environment?

The first step is to prepare your environment by creating the proper folder structure and making sure you have the necessary images.

• Create a folder called stacks: This will be the root of your project.

• Inside stacks, create a subfolder called app: Here we will store the Dockerfile that specifies the Nginx server.

  mkdir stacks cd stacks mkdir app

To complete this basic configuration, generate the Docker image from the Dockerfile using the following command:

docker build -t frontend ./app

This will create an image labeled frontend. Make sure that the image was created correctly using docker images.

What does the docker-compose.yaml file involve?

The docker-compose.yaml file is essential for defining and managing the services you want to run. In this file, you will specify details such as service deployment and network configurations. This is where Docker Compose and Swarm show their true synergy.

Services and networking

Within the YAML file, you define each service you want to deploy. It is crucial to note that when you use Docker Swarm, you work directly with images, not Dockerfile.

Example of basic configuration of services:

services: frontend: image: frontend:latest deploy: replicas: 3 update_config: parallelism: 2 delay: 10s networks: - frontend-net
networks: frontend-net: driver: overlay

YAML file keys:

• deploy: Manages replicas and cloning policies.
• Networks overlay: Essential for communication between services in Docker Swarm.

How do I deploy and manage services?

Once the YAML file is configured, it's time to deploy the services.

• Deploy the services using Docker Stack:

  docker stack deploy -c docker-compose.yml my_deployment

Managing services in Docker Desktop

Now that the services are deployed, you can manage them from Docker Desktop. Here you can monitor services, stop containers, and see Docker Swarm in action.

• Manually stopping containers: You can pause or delete containers to see how Docker Swarm handles failures by creating new instances automatically. This automated feature ensures that the service is always available.

Service removal and cleanup.

Finally, to stop and clean up all services and networks:

docker stack rm my_deploymentdocker swarm leave --force.

This will remove all traces of the deployment.

Final considerations: When to use Docker Swarm?

Docker Swarm is ideal for small to medium-sized projects due to certain limitations, such as maximum support for 100 containers. However, it is an excellent entry point before scaling to more robust solutions such as Kubernetes.

With this convenient integration of Docker Swarm and Compose, you can manage containers efficiently and effectively, providing flexibility and resiliency to your development environment. Go ahead and experiment and explore the opportunities that Docker Swarm offers to improve your container orchestration skills!