Hello. In this tutorial, we will talk about Docker Save.
1. What is Docker?
Docker is an open-source platform used for the containerization of applications. It allows developers to package their applications along with their dependencies, libraries, and other necessary components into a single container that can run reliably and consistently on any platform. The containerization technology provided by Docker ensures that the application behaves the same way regardless of the underlying infrastructure. Some benefits of Docker are:
- Portability: Docker containers can run on any platform, regardless of the underlying infrastructure. This makes it easy to move applications between development, testing, and production environments.
- Scalability: Docker allows you to quickly and easily scale your application by adding or removing containers as needed, without having to make changes to the underlying infrastructure.
- Isolation: Docker provides a high level of isolation between applications, ensuring that each container runs independently of others, without interfering with each other.
- Efficiency: Docker containers are lightweight and efficient, consuming fewer resources than traditional virtual machines. This allows you to run more applications on the same hardware.
- Consistency: Docker ensures that applications behave the same way across different environments, making it easier to test and deploy new versions of your application.
- Security: Docker provides built-in security features that help protect your applications from external threats. Docker containers are isolated from each other and the underlying infrastructure, reducing the risk of attacks.
Overall, Docker provides a powerful platform for building, testing, and deploying applications that is both efficient and reliable.
1.1 What is Docker used for?
It is used for –
- For environment replication, while the code runs locally on the machine.
- For numerous deployment phases i.e. Dev/Test/QA.
- For version control and distributing the application’s OS within a team.
1.2 Basic Docker Terminology?
- Image: Representation of Docker container i.e. a JAR or WAR file in Java.
- Container: Runtime of Docker i.e. a deployed and running Docker image. For example, an executable Spring Boot jar.
- Engine: The code that manages, creates, and runs the Docker containers.
- Hub: A public developer’s registry to distribute their code.
- Repository: A collection of Docker-related images i.e. different versions of the same application.
1.3 Setting up Docker
If someone needs to go through the Docker installation, please watch this video.
2. Docker Save
Docker save is a command-line utility that allows you to save a Docker image as a tar archive. The saved image can be exported and shared with others or stored as a backup for future use. Here are some of the benefits of using Docker Save:
- Portability: With Docker Save, you can easily move Docker images between different environments. You can save an image on one system and then transfer it to another system, which can then load and run the image.
- Backup: By using Docker Save to backup images, you can ensure that your images are always available, even if your Docker registry or image repository is offline.
- Offline distribution: If you have a slow or unreliable internet connection, you can use Docker Save to distribute Docker images offline. Simply save the image as a tar archive, transfer it to another system, and then load it using the Docker load command.
- Security: By saving images as tar archives, you can ensure that they are not modified or tampered with during transfer. This can help to prevent security breaches and ensure the integrity of your images.
Overall, Docker Save is a powerful tool for managing Docker images. It allows you to easily share, transfer, and back up images, making it a valuable asset for any Docker user.
2.1 Importance of Docker Save in container management
Docker Save is an important tool in container management for many reasons:
- Backup and Disaster Recovery: Docker Save allows users to back up Docker images, ensuring that they are always available even if the Docker registry or image repository is offline. This is crucial for disaster recovery and business continuity.
- Version Control: By saving Docker images using Docker Save, it is possible to create and manage multiple versions of the same image. This helps with tracking changes and maintaining version control.
- Sharing and Distribution: Docker Save enables users to share Docker images between different environments and users. It simplifies the process of moving images between different systems and helps to maintain consistency across the container deployment environment.
- Offline Distribution: Docker Save is especially useful for environments with slow or unreliable internet connections. By saving Docker images as tar archives, they can be distributed offline and loaded on another system using the Docker load command.
- Security: Docker save ensures that Docker images are not modified or tampered with during transfer, providing an additional layer of security to the container management environment.
Overall, Docker Save is an essential tool for container management. It enables users to maintain consistency and control over their Docker images and ensures that they are always available, secure, and distributed efficiently.
2.2 Syntax of the Docker Save command
The syntax of the docker save command is as follows:
Syntax
docker save [OPTIONS] IMAGE [IMAGE...]
Where OPTIONS are any additional command options, IMAGE is the name of the Docker image to be saved, and IMAGE... is an optional space-separated list of additional images to be saved. For example, to save a Docker image named myapp to a tar archive named myapp.tar, the following command could be used:
Example 1
docker save -o myapp.tar myapp
In this example, the -o option specifies the name of the output file. The myapp argument specifies the name of the image to be saved.
2.3 Loading saved images
To load a Docker image that has been saved as a tar archive using the docker save command, you can use the docker load command. The syntax of the docker load command is as follows:
Syntax
docker load [OPTIONS] < my_saved_image.tar
Where OPTIONS are any additional command options, and my_saved_image.tar is the name of the saved Docker image tar archive. The < symbol redirects the input from the tar archive file to the docker load command. For example, loading the myapp.tar Docker image tar archive that was saved in the previous example, the following command could be used:
Example 2
docker load -i myapp.tar
In this example, the -i option specifies the input file to be loaded. The myapp.tar argument specifies the name of the tar archive file to be loaded. Once the command is executed, the Docker image will be loaded and can be used to create new containers or run existing ones.
2.4 Exporting containers with Docker save
In addition to saving Docker images, the docker save command can also be used to export Docker containers. When exporting a container, Docker saves the container’s file system and metadata as a tar archive, which can be imported to create a new image or container. The syntax for exporting a container using the docker save command is as follows:
Syntax
docker export [OPTIONS] CONTAINER > container.tar
Where OPTIONS are any additional command options, CONTAINER is the name or ID of the container to be exported, and container.tar is the name of the output file to which the container will be exported. For example, to export a container named my_container to a tar archive named my_container.tar, the following command could be used:
Example 3
docker export my_container > my_container.tar
In this example, the my_container argument specifies the name of the container to be exported and the > symbol redirects the output to the my_container.tar file. Once the container is exported, it can be imported on another system using the docker import command to create a new Docker image:
Example 4
docker import my_container.tar my_new_image
In this example, my_container.tar is the name of the exported container tar archive file, and my_new_image is the name of the new Docker image that will be created. The docker import command creates a new Docker image from the exported container file system and metadata. That concludes this tutorial, and I hope that it provided you with the information you were seeking. Enjoy your learning journey, and don’t forget to share!
3. Conclusion
In conclusion, docker save and docker load commands are essential tools for managing Docker containers and images. The docker save command allows users to save Docker images and containers as tar archives, which can be easily transferred between different systems, stored as backups and shared with other users. The docker load command, on the other hand, enables users to load and import Docker images and containers from saved tar archives, making it easy to reuse and deploy Docker containers and images across different environments. By leveraging these commands, Docker users can improve their container management workflow, enhance their security, and ensure business continuity in the face of disaster.
4. Summary
Docker Save and Docker Load are two important commands used in Docker container management. The Docker save command enables users to save Docker images and containers as tar archives, which can be easily transferred between different systems, stored as backups and shared with other users. This command is useful for offline distribution, disaster recovery, and version control. The Docker load command is used to load and import Docker images and containers from saved tar archives, making it easy to reuse and deploy Docker containers and images across different environments. These commands are essential tools for Docker users to enhance their container management workflow, improve security, and ensure business continuity. You can also download the commands used in this tutorial from the Downloads section.
5. Download the Project
This was a tutorial on Docker Save.
You can download the full source code of this example here: Docker Save
