In this article, we'll be looking at Linux containerization with Docker. We'll cover what containers are, how they work, and why you might want to use them. We'll also go over some basic commands for working with Docker containers. By the end of this article, you should have a good understanding of how to use Docker to containerize your applications.
Containers are a way of isolating your application from the rest of the system. They work by packaging up the application and its dependencies into a single unit that can be run anywhere. This isolation makes it much easier to move your application around and ensures that it will always run the same, no matter where it's deployed.
Containers are built on top of a Linux kernel feature called namespaces. Namespaces allow you to create isolated environments within a single Linux system. This isolation is what allows you to run multiple containers on a single host.
Each container has its own set of namespaces, which provides it with its own isolated environment. This environment includes its own process tree, network interfaces, mount points, and more. This isolation means that a containerized application will always run the same, no matter where it's deployed.
There are a few reasons you might want to use containers.
Containers are portable, meaning they can be easily moved from one system to another. This makes it easy to deploy your applications on multiple platforms.
Containers are also reproducible, meaning that they can be easily recreated. This is important for development and testing, as you can always be sure that your application will run the same in production as it does in your development environment.
Containers provide resource isolation, meaning that each container has its own isolated environment. This isolation ensures that your application will always have the resources it needs to run, regardless of what other applications are running on the same system.
Now that we've covered what containers are and why you might want to use them, let's take a look at how to use Docker to containerize your applications.
Docker is a tool that makes it easy to work with containers. It provides a command-line interface for managing containers, as well as a platform for sharing container images.
Before you can use Docker, you'll need to install it on your system. Docker is available for a variety of platforms, including Linux, macOS, and Windows.
To install Docker on Ubuntu, you can use the following command:
sudo apt-get install docker.io
Once Docker is installed, you can use the docker
command to manage containers.
To create a container, you can use the docker run
command. This command takes a container image and creates a new container from it. For example, to create a container from the Ubuntu image, you can use the following command:
docker run -it ubuntu
This command will pull the Ubuntu image from Docker Hub and create a new container from it. The -it
flag tells Docker to run the container in interactive mode.
Once the container is running, you'll be placed into a Bash shell inside the container. From here, you can run any commands you like. When you're finished, you can exit the container by typing exit
.
To view a list of all the containers on your system, you can use the docker ps
command. This command will show you the containers that are currently running, as well as the containers that have been created but are not running.
To view all containers, including those that have been created but are not running, you can use the -a
flag.
To start a container that is not currently running, you can use the docker start
command. For example, to start the container we created in the previous section, you can use the following command:
docker start ubuntu
To stop a container that is currently running, you can use the docker stop
command. For example, to stop the container we created in the previous section, you can use the following command:
docker stop ubuntu
To delete a container, you can use the docker rm
command. For example, to delete the container we created in the previous section, you can use the following command:
docker rm ubuntu
In this article, we've looked at what containers are and how to use Docker to containerize your applications. We've also covered some basic commands for working with Docker containers. By the end of this article, you should have a good understanding of how to use Docker to containerize your applications.