example-plugin

Example Check Plugin

This directory contains an example of a check plugin for clusterlint. Plugins can be used to implement checks that are not appropriate for addition to clusterlint itself for whatever reason - e.g., because they encode a best practice that is highly specific to a particular organization.

Building

Build the plugin as a Go plugin:

$ go build -buildmode=plugin github.com/digitalocean/clusterlint/example-plugin

You should end up with a file called example-plugin.so in your working directory.

Usage

You can then use the plugin by loading it into clusterlint at runtime:

$ clusterlint --plugins=./example-plugin.so run -c example-plugin
[suggestion] kube-system/pod/kubelet-rubber-stamp-f6756bc78-6sl9r: You probably don't want to run the example plugin.

The example plugin produces a suggestion for each pod running in the cluster, just to show what a plugin can do.

Caveats

Supported Platforms

Go plugins are supported only on Linux and macOS.

Versioning

Plugins must be built against the exact same version of the clusterlint codebase as the clusterlint binary you are using, as well as against the same version of all dependencies.

If the version used to build the plugin doesn't match the binary version you'll get a message like:

plugin.Open("./example-plugin"): plugin was built with a different version of package github.com/digitalocean/clusterlint/kube

We recommend using go module versioning to ensure you're building your plugin against code from the clusterlint release you're using. If you build clusterlint using the vendored dependencies, make sure you also build your plugins using the vendored dependencies.