Docker Export and Import
Introduction
Docker is an open-source platform that allows you to automate the deployment, scaling, and management of applications using containerization. Containers provide an isolated environment to run applications and their dependencies, making it easier to deploy and maintain applications across different environments.
In this article, we will explore the docker export and docker import commands, which allow us to create images from containers and import them into other Docker installations.
Docker Export
The docker export command allows you to export the contents of a container as a tar archive. This archive can be shared with others or imported into another Docker installation.
To export a container, you need to know its container ID or name. You can find the ID or name of a running container using the docker ps command. Once you have the container ID or name, you can use the docker export command as follows:
docker export [OPTIONS] CONTAINER
Let's say we have a container named my-container that we want to export. We can use the following command to export it:
docker export my-container > my-container.tar
This command exports the container as a tar archive and saves it to the my-container.tar file.
Docker Import
The docker import command allows you to import a tar archive created by the docker export command and create a new Docker image from it.
To import a tar archive, you need to provide the path to the archive and specify the repository and tag for the new image. The repository and tag are used to identify the image in Docker.
The docker import command has the following syntax:
docker import [OPTIONS] file|URL|- [REPOSITORY[:TAG]]
Let's say we have the my-container.tar file that we exported earlier. We can use the following command to import it as a new Docker image:
docker import my-container.tar my-image:tag
This command imports the my-container.tar file and creates a new image named my-image with the specified tag.
Example
To illustrate how to use docker export and docker import, let's consider a simple scenario. We have a container running an Apache web server, and we want to export it, transfer it to another machine, and import it there.
First, let's export the container as a tar archive:
docker export my-apache-container > my-apache-container.tar
This command exports the my-apache-container container as a tar archive named my-apache-container.tar.
Next, we transfer the my-apache-container.tar file to another machine using a file transfer protocol like SCP or SFTP.
Once we have the tar archive on the new machine, we can import it as a new Docker image:
docker import my-apache-container.tar my-new-apache-image:tag
This command imports the my-apache-container.tar file and creates a new image named my-new-apache-image with the specified tag.
Now, we can run a container using the newly imported image:
docker run -d -p 80:80 my-new-apache-image:tag
This command runs a container using the my-new-apache-image image and maps port 80 of the container to port 80 of the host machine.
Conclusion
The docker export and docker import commands are useful for transferring containers between Docker installations. They allow you to create container images from existing containers and share or import them into different environments. This can be helpful in scenarios where you want to deploy the same set of containers across multiple machines or share containers with others.
In this article, we explored how to use these commands, along with a practical example. By mastering these commands, you can easily move containers between different Docker installations and streamline your deployment process.
