docs/content/v2.0-preview/packages/functions.md

title	weight	description
Functions	100	Functions extend Crossplane with new ways to configure composition

Functions extend Crossplane with new ways to configure [composition]({{<ref "../composition">}}).

You can use different composition functions to configure what Crossplane does when someone creates or updates a [composite resource (XR)]({{<ref "../composition/composite-resources">}}).

{{<hint "important">}} This page is a work in progress.

Functions are packages, like [Providers]({{<ref "./providers">}}) and [Configurations]({{<ref "./configurations">}}). Their APIs are similar. You install and configure them the same way as a provider.

Read the [composition]({{<ref "../composition/compositions">}}) documentation to learn how to use functions in a composition. {{}}

Install a Function

Install a Function with a Crossplane {{}}Function{{}} object setting the {{}}spec.package{{}} value to the location of the function package.

{{< hint "important" >}} Beginning with Crossplane version 1.20.0 Crossplane uses the crossplane-contrib GitHub Container Registry at xpkg.crossplane.io by default for downloading and installing packages.

Specify the full domain name with the package or change the default Crossplane registry with the --registry flag on the [Crossplane pod]({{<ref "../guides/pods">}}) {{< /hint >}}

For example, to install the patch and transform function,

apiVersion: pkg.crossplane.io/v1
kind: Function
metadata:
  name: crossplane-contrib-function-patch-and-transform
spec:
  package: xpkg.crossplane.io/crossplane-contrib/function-patch-and-transform:v0.8.2

By default, the Function pod installs in the same namespace as Crossplane (crossplane-system).

{{<hint "note" >}} Functions are part of the {{}}pkg.crossplane.io{{}} group.

The {{}}meta.pkg.crossplane.io{{}} group is for creating Function packages.

Instructions on building Functions are outside of the scope of this document.
Read the Crossplane contributing Function Development Guide for more information.

For information on the specification of Function packages read the Crossplane Function Package specification.

apiVersion: meta.pkg.crossplane.io/v1
kind: Function
metadata:
  name: provider-aws
spec:
# Removed for brevity

{{}}