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.
Note: Docker Engine managed plugins are currently not supported on Windows daemons.
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.
Install the sshfs
plugin.
$ 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:
host
network.CAP_SYS_ADMIN
capability, which allows the plugin to run the mount
command.Check that the plugin is enabled in the output of docker plugin ls
.
$ docker plugin ls ID NAME TAG DESCRIPTION ENABLED 69553ca1d789 vieux/sshfs latest the `sshfs` plugin true
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.
$ docker volume create \ -d vieux/sshfs \ --name sshvolume \ -o sshcmd=user@1.2.3.4:/remote sshvolume
Verify that the volume was created successfully.
$ docker volume ls DRIVER NAME vieux/sshfs sshvolume
Start a container that uses the volume sshvolume
.
$ 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.
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.
$ 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 describes the plugin. See the plugins config reference.
Consider the following config.json
file.
{ "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.
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>
.