Table of contents
Let's move forward in our journey of learning DevOps and have a Deep dive in Docker.
After creating a Dockerfile for a simple web application (to-do-list) and deploying it, now we will learn about a tool that is used to run multiple containers together. This tool is none other than Docker Compose.
Docker Compose
Docker Compose is a tool that helps you manage multiple Docker containers as a single application. It allows you to define the services that make up your application, how they should be connected, and how they should share resources.
So, why do we need Docker Compose? Well, when you're building an application, you often need to use multiple containers to make it work. For example, you might need a container for the web server, another container for the database, and another container for the API. But managing all these containers can be tricky. That's where Docker Compose comes in.
Docker Compose helps you define how all your containers should work together. It's like a conductor that makes sure all the different parts of your application are working together smoothly. It allows you to start, stop, and manage all your containers as a group, rather than having to manage them individually.
Now, how does Docker Compose differ from other Docker tools? Well, other Docker tools, like Docker itself, are focused on building and running individual containers. Docker Compose, on the other hand, is focused on managing multiple containers as a group. It helps you define how all your containers should work together, rather than just building and running individual containers.
To use Docker Compose, you create a file called a "Docker Compose file" that defines the services that make up your application. This file is written in a simple syntax that allows you to specify the containers you want to use, how they should be connected, and how they should share resources.
Once you have created your Docker Compose file, you can use the Docker Compose command-line tool to start, stop, and manage your application. This tool allows you to easily start and stop all the containers in your application, as well as view the logs and status of each container.
What is YAML?
Docker Compose uses YAML (YAML Ain't Markup Language) files to define the configuration for your application.
YAML is a human-readable data serialization format that is commonly used for configuration files. In Docker Compose, you create a YAML file that defines the services that make up your application, how they should be connected, and how they should share resources. This YAML file is then used by Docker Compose to start, stop, and manage your application
Tasks
Learn how to use the docker-compose.yml file, to set up the environment, configure the services and links between different containers, and also to use environment variables in the docker-compose.yml file
Click here for a beginner's best explanation for creating a Docker-Compose file.
The steps to follow are :
Step 1 : Create a Directory Structure
Step 2 : Create a Dockerfile for Webapp
Step 3 : Create a Docker-Compose file
Step 4 : Build Webapp Image
Step 5 : Launch Docker Containers
Step 6 : Update Content in the Web App
2)
- Pull a pre-existing Docker image from a public repository (e.g. Docker Hub) and run it on your local machine. Run the container as a non-root user (Hint- Use
usermodcommand to give user permission to docker). Make sure you reboot instance after giving permission to user.
Inspect the container's running processes and exposed ports using the docker inspect command.
Use the docker logs command to view the container's log output.
- Use the docker stop and docker start commands to stop and start the container.
- Use the docker rm command to remove the container when you're done.
Thanks for following until here.If you gained some clarity regarding important Docker topics do consider following me.See you in the next one.