How to store docker image on data disk

Docker is an important tool for modern application development and deployment. It is centered on building, packaging and distributing applications, and running these applications in different environments. However, a common question is: How to store Docker images on a data disk so that they can be shared and reused between containers? This article will discuss this problem and provide some solutions.

What is a Docker image?

Before discussing how to store Docker images on a data disk, we need to first understand what a Docker image is. Simply put, a Docker image is a read-only binary file that can be used to run a container in Docker. It contains the application, configuration files and dependencies, as well as a base image, which is the building block of the Docker image.

Normally, Docker images are stored on the host's local disk, but this can lead to the following problems:

• Capacity issues: Docker images take up a lot of disk space, especially when you need When storing a large number of images.
• Distribution issue: When your team needs to use the same image on different hosts, it must be distributed to each host.

Therefore, storing Docker images on data disks is a feasible solution.

Methods to store Docker images on data disks

The following discusses some methods to store Docker images on data disks.

Method 1: Use a custom Docker data directory

Docker stores data in the /var/lib/docker directory by default, but you can replace the default directory with a custom directory. To change the Docker data directory:

1. Stop the Docker service.

sudo systemctl stop docker

2. Create a new directory to store the Docker image.

sudo mkdir -p /mnt/data/docker

3. Update the Docker systemd unit files to use the new directory.

sudo nano /etc/systemd/system/docker.service.d/custom-exec.conf

Add the following:

[Service]
ExecStart=
ExecStart=/usr/bin/dockerd --graph="/mnt/data/docker"

4. Reload the systemd unit file and restart Docker.

sudo systemctl daemon-reload
sudo systemctl start docker

Now, all new Docker images will be stored in the /mnt/data/docker directory.

Method 2: Use Docker Registry

Docker Registry is a centralized repository for storing public and private Docker images. By using the Docker Registry, you can easily distribute Docker images to other machines or colleagues on your team.

You can choose to use the public Registry provided by Docker or build your own private Registry. If you choose to build your own private registry, check out the official Docker documentation for details.

Method 3: Use the Docker storage driver

The Docker storage driver allows you to store Docker images in different places, including network storage and cloud storage. By default, Docker uses the Overlay2 storage driver to store images on the host's local disk. If you want to store the Docker image on a data disk, you can use other storage drivers, such as:

• btrfs storage driver
• aufs storage driver
• ZFS Storage Driver

Please note that using a different storage driver may involve additional system configuration and software dependencies.

Summary

Storing Docker images on a data disk is not difficult, you can do this using a custom Docker data directory, the Docker Registry, or a different storage driver. During your selection, remember to consider storage capacity, performance, and security. Hopefully you'll be able to find what works best for your team's needs.

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