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[20.10 backport] fixed the plugin command docker-runc #3820

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merged 1 commit into from Oct 21, 2022
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[20.10 backport] fixed the plugin command docker-runc #3820

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49 changes: 24 additions & 25 deletions docs/extend/index.md
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Expand Up @@ -14,9 +14,9 @@ keywords: "API, Usage, plugins, documentation, developer"

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

Docker Engine's plugin system allows you to install, start, stop, and remove
plugins using Docker Engine.
Expand Down Expand Up @@ -70,7 +70,7 @@ enabled, and use it to create a volume.

- It needs access to the `host` network.
- It needs the `CAP_SYS_ADMIN` capability, which allows the plugin to run
the `mount` command.
the `mount` command.

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

Expand Down Expand Up @@ -115,6 +115,7 @@ enabled, and use it to create a volume.
```

6. Remove the volume `sshvolume`

```console
$ docker volume rm sshvolume

Expand All @@ -126,15 +127,15 @@ remove it, use the `docker plugin remove` command. For other available
commands and options, see the
[command line reference](https://docs.docker.com/engine/reference/commandline/cli/).


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

```console
$ git clone https://github.com/vieux/docker-volume-sshfs
Expand All @@ -155,19 +156,19 @@ Consider the following `config.json` file.

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

Expand All @@ -187,7 +188,6 @@ 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>`.


## Debugging plugins

Stdout of a plugin is redirected to dockerd logs. Such entries have a
Expand Down Expand Up @@ -226,7 +226,7 @@ plugins. This is specifically useful to collect plugin logs if they are
redirected to a file.

```console
$ sudo docker-runc --root /var/run/docker/plugins/runtime-root/moby-plugins list
$ sudo runc --root /run/docker/runtime-runc/plugins.moby list

ID PID STATUS BUNDLE CREATED OWNER
93f1e7dbfe11c938782c2993628c895cf28e2274072c4a346a6002446c949b25 15806 running /run/docker/containerd/daemon/io.containerd.runtime.v1.linux/moby-plugins/93f1e7dbfe11c938782c2993628c895cf28e2274072c4a346a6002446c949b25 2018-02-08T21:40:08.621358213Z root
Expand All @@ -235,14 +235,14 @@ c5bb4b90941efcaccca999439ed06d6a6affdde7081bb34dc84126b57b3e793d 14984 r
```

```console
$ sudo docker-runc --root /var/run/docker/plugins/runtime-root/moby-plugins exec 93f1e7dbfe11c938782c2993628c895cf28e2274072c4a346a6002446c949b25 cat /var/log/plugin.log
$ sudo runc --root /run/docker/runtime-runc/plugins.moby exec 93f1e7dbfe11c938782c2993628c895cf28e2274072c4a346a6002446c949b25 cat /var/log/plugin.log
```

If the plugin has a built-in shell, then exec into the plugin can be done as
follows:

```console
$ sudo docker-runc --root /var/run/docker/plugins/runtime-root/moby-plugins exec -t 93f1e7dbfe11c938782c2993628c895cf28e2274072c4a346a6002446c949b25 sh
$ sudo runc --root /run/docker/runtime-runc/plugins.moby exec -t 93f1e7dbfe11c938782c2993628c895cf28e2274072c4a346a6002446c949b25 sh
```

#### Using curl to debug plugin socket issues.
Expand All @@ -253,7 +253,6 @@ docker host to volume and network plugins using curl 7.47.0 to ensure that
the plugin is listening on the said socket. For a well functioning plugin,
these basic requests should work. Note that plugin sockets are available on the host under `/var/run/docker/plugins/<pluginID>`


```console
$ curl -H "Content-Type: application/json" -XPOST -d '{}' --unix-socket /var/run/docker/plugins/e8a37ba56fc879c991f7d7921901723c64df6b42b87e6a0b055771ecf8477a6d/plugin.sock http:/VolumeDriver.List

Expand Down