helm-kustomize-plugin

README

helm-kustomize-plugin

An experimental kustomize plugin that allows to render helm charts into a kustomization.

This plugin is an improved, golang-based version of the example chartinflator plugin with helm built-in.

Motivation

Helm packages ("charts") provide a great way to share and reuse kubernetes applications and there is a lot of them. However there are some issues: For instance you cannot reuse a chart as is if it does not (yet) support a particular parameter/value you need and sometimes an additional kubectl command must be run (imperative!) to install a chart that could otherwise be installed as a single manifest using kubectl. The tiller server that comes with helm has certain issues as well. Though helm 3 will provide some solutions to these.

Kustomize solves these issues already declaratively by simply merging Kubernetes API objects (which grants users of a kustomization the freedom to change anything), by supporting all API object kinds and focussing on serverless rendering.

With helm support kustomize can be used as a generic tool to render kubernetes manifests. These can be applied using kubectl directly or using k8spkg which allows to manage their state within the cluster as well.

Requirements

• kustomize 3.0.0

Install

Install using curl (linux amd64):

mkdir -p $HOME/.config/kustomize/plugin/helm.kustomize.mgoltzsche.github.com/v1/chartrenderer
curl -L https://github.com/mgoltzsche/helm-kustomize-plugin/releases/latest/download/helm-kustomize-plugin > $HOME/.config/kustomize/plugin/helm.kustomize.mgoltzsche.github.com/v1/chartrenderer/ChartRenderer
chmod u+x $HOME/.config/kustomize/plugin/helm.kustomize.mgoltzsche.github.com/v1/chartrenderer/ChartRenderer

or using go:

go get github.com/mgoltzsche/helm-kustomize-plugin
mkdir -p $HOME/.config/kustomize/plugin/helm.kustomize.mgoltzsche.github.com/v1/chartrenderer
mv $GOPATH/bin/helm-kustomize-plugin $HOME/.config/kustomize/plugin/helm.kustomize.mgoltzsche.github.com/v1/chartrenderer/ChartRenderer

The kustomize plugin documentation provides more information.

Usage

A plugin descriptor specifying the helm repository, chart, version and values that should be used in a kubernetes-style resource can be referenced in the generators section of a kustomization.yaml and looks as follows:

apiVersion: helm.kustomize.mgoltzsche.github.com/v1
kind: ChartRenderer
metadata:
  name: <NAME>
  namespace: <NAMESPACE>
repository: <REPOSITORY>
chart: <CHART_NAME>
version: <CHART_VERSION>
valueFiles:
- <VALUE_FILE>
value: <VALUE_MAP>
exclude:
- apiVersion: <APIVERSION>
  kind: <KIND>
  namespace: <NAMESPACE>
  name: <NAME>

• repository (optional): a helm repository URL.
• chart: a chart name (using repository) or, when repository is not specified, a go-getter URL.
• valueFiles: a list of helm value file paths relative to the generator config file or to the chart.
• exclude: a list of selectors used to exclude matching objects from the rendered chart.

Example

Example kustomizations using this plugin can be found in the example directory. For instance cert-manager can be rendered and deployed like this:

kustomize build --enable_alpha_plugins github.com/mgoltzsche/helm-kustomize-plugin/example/cert-manager | kubectl apply -f -

Compatibility & security notice

Plugin support in kustomize is still an alpha feature.

Helm charts may access the local file system outside the kustomization directory.