mirror of https://github.com/docker/cli.git
99 lines
3.9 KiB
Markdown
99 lines
3.9 KiB
Markdown
---
|
|
description: "Writing Docker CLI Plugins"
|
|
keywords: "docker, cli plugin"
|
|
---
|
|
|
|
<!-- This file is maintained within the docker/cli GitHub
|
|
repository at https://github.com/docker/cli/. Make all
|
|
pull requests against that repo. If you see this file in
|
|
another repository, consider it read-only there, as it will
|
|
periodically be overwritten by the definitive file. Pull
|
|
requests which include edits to this file in other repositories
|
|
will be rejected.
|
|
-->
|
|
|
|
# Docker CLI Plugin Spec
|
|
|
|
The `docker` CLI supports adding additional top-level subcommands as
|
|
additional out-of-process commands which can be installed
|
|
independently. These plugins run on the client side and should not be
|
|
confused with "plugins" which run on the server.
|
|
|
|
This document contains information for authors of such plugins.
|
|
|
|
## Requirements for CLI Plugins
|
|
|
|
### Naming
|
|
|
|
A valid CLI plugin name consists only of lower case letters `a-z`
|
|
and the digits `0-9`. The leading character must be a letter. A valid
|
|
name therefore would match the regex `^[a-z][a-z0-9]*$`.
|
|
|
|
The binary implementing a plugin must be named `docker-$name` where
|
|
`$name` is the name of the plugin. On Windows a `.exe` suffix is
|
|
mandatory.
|
|
|
|
## Required sub-commands
|
|
|
|
A CLI plugin must support being invoked in at least these two ways:
|
|
|
|
* `docker-$name docker-cli-plugin-metadata` -- outputs metadata about
|
|
the plugin.
|
|
* `docker-$name [GLOBAL OPTIONS] $name [OPTIONS AND FURTHER SUB
|
|
COMMANDS]` -- the primary entry point to the plugin's functionality.
|
|
|
|
A plugin may implement other subcommands but these will never be
|
|
invoked by the current Docker CLI. However doing so is strongly
|
|
discouraged: new subcommands may be added in the future without
|
|
consideration for additional non-specified subcommands which may be
|
|
used by plugins in the field.
|
|
|
|
### The `docker-cli-plugin-metadata` subcommand
|
|
|
|
When invoked in this manner the plugin must produce a JSON object
|
|
(and nothing else) on its standard output and exit success (0).
|
|
|
|
The JSON object has the following defined keys:
|
|
* `SchemaVersion` (_string_) mandatory: must contain precisely "0.1.0".
|
|
* `Vendor` (_string_) mandatory: contains the name of the plugin vendor/author. May be truncated to 11 characters in some display contexts.
|
|
* `ShortDescription` (_string_) optional: a short description of the plugin, suitable for a single line help message.
|
|
* `Version` (_string_) optional: the version of the plugin, this is considered to be an opaque string by the core and therefore has no restrictions on its syntax.
|
|
* `URL` (_string_) optional: a pointer to the plugin's web page.
|
|
|
|
A binary which does not correctly output the metadata
|
|
(e.g. syntactically invalid, missing mandatory keys etc) is not
|
|
considered a valid CLI plugin and will not be run.
|
|
|
|
### The primary entry point subcommand
|
|
|
|
This is the entry point for actually running the plugin. It maybe have
|
|
options or further subcommands.
|
|
|
|
#### Required global options
|
|
|
|
A plugin is required to support all of the global options of the
|
|
top-level CLI, i.e. those listed by `man docker 1` with the exception
|
|
of `-v`.
|
|
|
|
## Installation
|
|
|
|
Plugins distributed in packages for system wide installation on
|
|
Unix(-like) systems should be installed in either
|
|
`/usr/lib/docker/cli-plugins` or `/usr/libexec/docker/cli-plugins`
|
|
depending on which of `/usr/lib` and `/usr/libexec` is usual on that
|
|
system. System Administrators may also choose to manually install into
|
|
the `/usr/local/lib` or `/usr/local/libexec` equivalents but packages
|
|
should not do so.
|
|
|
|
Plugins distributed on Windows for system wide installation should be
|
|
installed in `%PROGRAMDATA%\Docker\cli-plugins`.
|
|
|
|
User's may on all systems install plugins into `~/.docker/cli-plugins`.
|
|
|
|
## Implementing a plugin in Go
|
|
|
|
When writing a plugin in Go the easiest way to meet the above
|
|
requirements is to simply call the
|
|
`github.com/docker/cli/cli-plugins/plugin.Run` method from your `main`
|
|
function to instantiate the plugin.
|