github.com/flavio/docker@v0.1.3-0.20170117145210-f63d1a6eec47/docs/extend/index.md

---
description: Develop and use a plugin with the managed plugin system
keywords: "API, Usage, plugins, documentation, developer"
title: Managed plugin system
---

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# Docker Engine managed plugin system

* [Installing and using a plugin](index.md#installing-and-using-a-plugin)
* [Developing a plugin](index.md#developing-a-plugin)

Docker Engine's plugins system allows you to install, start, stop, and remove
plugins using Docker Engine. This mechanism is currently only available for
volume drivers, but more plugin driver types will be available in future releases.

For information about the legacy plugin system available in Docker Engine 1.12
and earlier, see [Understand legacy Docker Engine plugins](legacy_plugins.md).

> **Note**: Docker Engine managed plugins are currently not supported
on Windows daemons.

## Installing and using a plugin

Plugins are distributed as Docker images and can be hosted on Docker Hub or on
a private registry.

To install a plugin, use the `docker plugin install` command, which pulls the
plugin from Docker hub or your private registry, prompts you to grant
permissions or capabilities if necessary, and enables the plugin.

To check the status of installed plugins, use the `docker plugin ls` command.
Plugins that start successfully are listed as enabled in the output.

After a plugin is installed, you can use it as an option for another Docker
operation, such as creating a volume.

In the following example, you install the `sshfs` plugin, verify that it is
enabled, and use it to create a volume.

1.  Install the `sshfs` plugin.

    ```bash
    $ docker plugin install vieux/sshfs

    Plugin "vieux/sshfs" is requesting the following privileges:
    - network: [host]
    - capabilities: [CAP_SYS_ADMIN]
    Do you grant the above permissions? [y/N] y

    vieux/sshfs
    ```

    The plugin requests 2 privileges:
    - It needs access to the `host` network.
    - It needs the `CAP_SYS_ADMIN` capability, which allows the plugin to run
    the `mount` command.

2.  Check that the plugin is enabled in the output of `docker plugin ls`.

    ```bash
    $ docker plugin ls

    ID                    NAME                  TAG                 DESCRIPTION                   ENABLED
    69553ca1d789          vieux/sshfs           latest              the `sshfs` plugin            true
    ```

3.  Create a volume using the plugin.
    This example mounts the `/remote` directory on host `1.2.3.4` into a
    volume named `sshvolume`. This volume can now be mounted into containers.

    ```bash
    $ docker volume create \
      -d vieux/sshfs \
      --name sshvolume \
      -o sshcmd=user@1.2.3.4:/remote

    sshvolume
    ```
4.  Verify that the volume was created successfully.

    ```bash
    $ docker volume ls

    DRIVER              NAME
    vieux/sshfs         sshvolume
    ```

5.  Start a container that uses the volume `sshvolume`.

    ```bash
    $ docker run -v sshvolume:/data busybox ls /data

    <content of /remote on machine 1.2.3.4>
    ```

To disable a plugin, use the `docker plugin disable` command. To completely
remove it, use the `docker plugin remove` command. For other available
commands and options, see the
[command line reference](../reference/commandline/index.md).

## Developing a plugin

#### The rootfs directory
The `rootfs` directory represents the root filesystem of the plugin. In this
example, it was created from a Dockerfile:

>**Note:** The `/run/docker/plugins` directory is mandatory inside of the
plugin's filesystem for docker to communicate with the plugin.

```bash
$ git clone https://github.com/vieux/docker-volume-sshfs
$ cd docker-volume-sshfs
$ docker build -t rootfsimage .
$ id=$(docker create rootfsimage true) # id was cd851ce43a403 when the image was created
$ sudo mkdir -p myplugin/rootfs
$ sudo docker export "$id" | sudo tar -x -C myplugin/rootfs
$ docker rm -vf "$id"
$ docker rmi rootfsimage
```

#### The config.json file

The `config.json` file describes the plugin. See the [plugins config reference](config.md).

Consider the following `config.json` file.

```json
{
	"description": "sshFS plugin for Docker",
	"documentation": "https://docs.docker.com/engine/extend/plugins/",
	"entrypoint": ["/go/bin/docker-volume-sshfs"],
	"network": {
		   "type": "host"
		   },
	"interface" : {
		   "types": ["docker.volumedriver/1.0"],
		   "socket": "sshfs.sock"
	},
	"capabilities": ["CAP_SYS_ADMIN"]
}
```

This plugin is a volume driver. It requires a `host` network and the
`CAP_SYS_ADMIN` capability. It depends upon the `/go/bin/docker-volume-sshfs`
entrypoint and uses the `/run/docker/plugins/sshfs.sock` socket to communicate
with Docker Engine. This plugin has no runtime parameters.

### Creating the plugin

A new plugin can be created by running
`docker plugin create <plugin-name> ./path/to/plugin/data` where the plugin
data contains a plugin configuration file `config.json` and a root filesystem
in subdirectory `rootfs`. 

After that the plugin `<plugin-name>` will show up in `docker plugin ls`.
Plugins can be pushed to remote registries with
`docker plugin push <plugin-name>`.