How to use docker plugin push command to share a plugin

Introduction

In this lab, you will learn how to share Docker plugins by pushing them to a registry. You will begin by listing the plugins currently installed in your Docker environment to understand what is available.

Following that, you will practice pushing a Docker plugin to a registry, enabling you to share or store your plugins. Finally, you will learn how to push a plugin with a specific tag, providing version control and organization for your shared plugins.

Skills Graph

List existing plugins

In this step, you will learn how to list the existing plugins installed in your Docker environment. Plugins extend Docker's functionality, allowing you to add features like volume management, network drivers, and more.

To list the currently installed Docker plugins, you can use the docker plugin ls command. This command will show you a list of plugins, their status, and other relevant information.

Let's try listing the plugins in your environment.

docker plugin ls

You should see output similar to this (the exact output may vary depending on your environment):

ID    NAME    DESCRIPTION    ENABLED

In a default LabEx environment, there are typically no plugins installed by default, so the output will likely show an empty list or only essential built-in components that are not listed as separate plugins. This is expected.

The docker plugin ls command is useful for quickly seeing which plugins are available and whether they are enabled or disabled. This is the first step in managing Docker plugins.

Push a plugin to a registry

In this step, you will learn how to push a Docker plugin to a registry. Pushing a plugin allows you to share it with others or store it for later use. Before you can push a plugin, you need to have a plugin available. For demonstration purposes, we will use a simple example plugin.

First, let's pull a sample plugin image. We will use the vieux/sshfs plugin as an example. This plugin allows you to use SSHFS for Docker volumes.

docker plugin install vieux/sshfs

You will be prompted to accept the plugin's capabilities. Type y and press Enter.

Plugin "vieux/sshfs" is requesting the following privileges:
 - network: [host]
 - mount: [/dev/fuse]
 - allow-devices: [fuse]
 - authz: []
 - capabilities: [CAP_SYS_ADMIN]
Do you grant the plugin these privileges? [y/N] y

After the plugin is installed, you can verify its installation and status using the docker plugin ls command again.

docker plugin ls

You should now see the vieux/sshfs plugin listed and its status should be true (enabled).

ID                  NAME                DESCRIPTION                         ENABLED
<plugin_id>         vieux/sshfs         Mount sshfs volumes                 true

Now that we have a plugin installed, we can push it to a registry. To push a plugin, you use the docker plugin push command followed by the plugin name. For this example, we will push the vieux/sshfs plugin.

docker plugin push vieux/sshfs

Since we are not pushing to a specific registry (like Docker Hub), this command will attempt to push to the default registry. For a real-world scenario, you would need to log in to your registry first using docker login and specify the registry in the push command (e.g., docker plugin push your-registry.com/vieux/sshfs).

The output will show the progress of the push operation.

The push refers to repository [docker.io/vieux/sshfs]
Pushed plugin vieux/sshfs:<tag>

This command pushes the plugin to the specified registry. If no tag is specified, the latest tag is usually used by default.

Push a plugin with a specific tag

In this step, you will learn how to push a Docker plugin to a registry with a specific tag. Tagging allows you to version your plugins and manage different releases.

In the previous step, we installed and pushed the vieux/sshfs plugin. When we pushed it without specifying a tag, it likely used the default latest tag. Now, let's push the same plugin but with a specific tag, for example, 1.0.

To push a plugin with a specific tag, you use the docker plugin push command followed by the plugin name and the tag separated by a colon (:).

docker plugin push vieux/sshfs:1.0

This command will push the vieux/sshfs plugin with the tag 1.0 to the default registry. Similar to the previous step, for a real-world scenario with a custom registry, you would include the registry address before the plugin name (e.g., docker plugin push your-registry.com/vieux/sshfs:1.0).

The output will show the progress of the push operation, indicating that the plugin is being pushed with the specified tag.

The push refers to repository [docker.io/vieux/sshfs]
Pushed plugin vieux/sshfs:1.0

By using tags, you can maintain multiple versions of your plugin in the registry. This is crucial for managing updates and ensuring compatibility. For example, you could have vieux/sshfs:1.0, vieux/sshfs:1.1, and vieux/sshfs:latest, allowing users to pull the specific version they need.

This concludes the steps on pushing Docker plugins. You have learned how to push a plugin to a registry and how to specify a tag during the push operation.

Summary

In this lab, you learned how to manage Docker plugins, specifically focusing on listing and pushing them to a registry. You started by using the docker plugin ls command to view installed plugins, understanding that a default environment might show an empty list.

Subsequently, you practiced pushing a plugin to a registry. This involved installing a sample plugin (vieux/sshfs) and then using the docker plugin push command to share it. You also learned how to push a plugin with a specific tag, allowing for versioning and better organization within the registry. These steps are crucial for sharing and managing custom or third-party Docker functionalities.