Extending the OpenShift cli with plugins - OpenShift cli (oc) | cli tools

Writing cli plugins
Installing and using cli plugins

You can write and install plugins to build on the default oc commands, allowing you to perform new and more complex tasks with the OpenShift cli.

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Writing cli plugins

You can write a plugin for the OpenShift cli in any programming language or script that allows you to write command-line commands. Note that you can not use a plugin to overwrite an existing oc command.

Procedure

This procedure creates a simple Bash plugin that prints a message to the terminal when the oc foo command is issued.

Create a file called oc-foo.

When naming your plugin file, keep the following in mind:
- The file must begin with oc- or kubectl- to be recognized as a plugin.
- The file name determines the command that invokes the plugin. For example, a plugin with the file name oc-foo-bar can be invoked by a command of oc foo bar. You can also use underscores if you want the command to contain dashes. For example, a plugin with the file name oc-foo_bar can be invoked by a command of oc foo-bar.

Add the following contents to the file.

#!/bin/bash

# optional argument handling
if [[ "$1" == "version" ]]
then
    echo "1.0.0"
    exit 0
fi

# optional argument handling
if [[ "$1" == "config" ]]
then
    echo $KUBECONFIG
    exit 0
fi

echo "I am a plugin named kubectl-foo"

After you install this plugin for the OpenShift cli, it can be invoked using the oc foo command.

Additional resources

Review the Sample plugin repository for an example of a plugin written in Go.
Review the cli runtime repository for a set of utilities to assist in writing plugins in Go.

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Installing and using cli plugins

After you write a custom plugin for the OpenShift cli, you must install the plugin before use.

Prerequisites

You must have the oc cli tool installed.
You must have a cli plugin file that begins with oc- or kubectl-.

Procedure

If necessary, update the plugin file to be executable.
```
$ chmod +x <plugin_file>
```
Place the file anywhere in your PATH, such as /usr/local/bin/.
```
$ sudo mv <plugin_file> /usr/local/bin/.
```
Run oc plugin list to make sure that the plugin is listed.
```
$ oc plugin list
```
Example output
```
The following compatible plugins are available:

/usr/local/bin/<plugin_file>
```
If your plugin is not listed here, verify that the file begins with oc- or kubectl-, is executable, and is on your PATH.
Invoke the new command or option introduced by the plugin.

For example, if you built and installed the kubectl-ns plugin from the Sample plugin repository, you can use the following command to view the current namespace.
```
$ oc ns
```
Note that the command to invoke the plugin depends on the plugin file name. For example, a plugin with the file name of oc-foo-bar is invoked by the oc foo bar command.