Helm Integration

Helm is the package management tool of choice for Kubernetes. Helm charts provide templating syntax for Kubernetes YAML manifest documents. With Helm we can create configurable deployments instead of just using static files. For more information about creating your own catalog of deployments, check out the docs at https://helm.sh/docs/intro/quickstart/.

RKE2 does not require any special configuration to use with Helm command-line tools. Just be sure you have properly set up your kubeconfig as per the section about cluster access. RKE2 does include some extra functionality to make deploying both traditional Kubernetes resource manifests and Helm Charts even easier with the rancher/helm-release CRD.

Automatically Deploying Manifests and Helm Charts

Any Kubernetes manifests found in /var/lib/rancher/rke2/server/manifests will automatically be deployed to RKE2 in a manner similar to kubectl apply, both on startup and when the file is changed on disk. Deleting files out of this directory will not delete the corresponding resources from the cluster.

Manifests deployed in this manner are managed as AddOn custom resources, and can be viewed by running kubectl get addon -A. By default, you will find AddOns for packaged components such as CoreDNS, Nginx-Ingress, and Metrics Server. AddOns are created automatically by the deploy controller, and are named based on their filename in the manifests directory.

It is also possible to deploy Helm charts as AddOns. RKE2 includes a Helm Controller that manages Helm charts using a HelmChart Custom Resource Definition (CRD).

File Naming Requirements

The AddOn name for each file in the manifest directory is derived from the file basename. Ensure that all files within the manifests directory (or within any subdirectories) have names that are unique, and adhere to Kubernetes object naming restrictions. Care should also be taken not to conflict with names in use by the default RKE2 packaged components, even if those components are disabled.

An example of an error that would be reported if the file name contains underscores:

`Failed to process config: failed to process /var/lib/rancher/rke2/server/manifests/example_manifest.yaml:
   Addon.k3s.cattle.io "example_manifest" is invalid: metadata.name: Invalid value: "example_manifest":
   a lowercase RFC 1123 subdomain must consist of lower case alphanumeric characters, '-' or '.', and must start and end with an alphanumeric character (e.g. 'example.com', regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?(\\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*')`

Disabling AddOns

The AddOns for packaged components listed above, in addition to AddOns for any additional manifests placed in the manifests directory, can be disabled with the --disable flag. Disabled AddOns are actively uninstalled from the cluster, and the source files deleted from the manifests directory.

For example, to disable CoreDNS from being installed on a new cluster, or to uninstall it and remove the manifest from an existing cluster, you can start RKE2 with disable: rke2-coredns in the config file. Multiple items can be disabled in a nested list.

# /etc/rancher/rke2/config.yaml
disable:
  - rke2-coredns
  - rke2-metrics-server

Using the Helm CRD

The HelmChart resource definition captures most of the options you would normally pass to the helm command-line tool. Here’s an example of how you might deploy Grafana from the default chart repository, overriding some of the default chart values. Note that the HelmChart resource itself is in the kube-system namespace, but the chart’s resources will be deployed to the monitoring namespace.

apiVersion: helm.cattle.io/v1
kind: HelmChart
metadata:
  name: grafana
  namespace: kube-system
spec:
  chart: stable/grafana
  targetNamespace: monitoring
  set:
    adminPassword: "NotVerySafePassword"
  valuesContent: |-
    image:
      tag: master
    env:
      GF_EXPLORE_ENABLED: true
    adminUser: admin
    sidecar:
      datasources:
        enabled: true

An example of deploying a helm chart from a private repo with authentication:

apiVersion: helm.cattle.io/v1
kind: HelmChart
metadata:
  namespace: kube-system
  name: example-app
spec:
  targetNamespace: example-space
  createNamespace: true
  version: v1.2.3
  chart: example-app
  repo: https://secure-repo.example.com
  authSecret:
    name: example-repo-auth
  repoCAConfigMap:
    name: example-repo-ca
  valuesContent: |-
    image:
      tag: v1.2.2
---
apiVersion: v1
kind: Secret
metadata:
  namespace: kube-system
  name: example-repo-auth
type: kubernetes.io/basic-auth
stringData:
  username: user
  password: pass
---
apiVersion: v1
kind: ConfigMap
metadata:
  namespace: kube-system
  name: example-repo-ca
data:
  ca.crt: |-
    -----BEGIN CERTIFICATE-----
    <YOUR CERTIFICATE>
    -----END CERTIFICATE-----

HelmChart Field Definitions

Field Default Description Helm Argument / Flag Equivalent

metadata.name

Helm Chart name

NAME

spec.chart

Helm Chart name in repository, or complete HTTPS URL to chart archive (.tgz)

CHART

spec.targetNamespace

default

Helm Chart target namespace

--namespace

spec.createNamespace

false

Create target namespace if not present

--create-namespace

spec.version

Helm Chart version (when installing from repository)

--version

spec.repo

Helm Chart repository URL

--repo

spec.repoCA

Verify certificates of HTTPS-enabled servers using this CA bundle. Should be a string containing one or more PEM-encoded CA Certificates.

--ca-file

spec.repoCAConfigMap

Reference to a ConfigMap containing CA Certificates to be be trusted by Helm. Can be used along with or instead of repoCA

--ca-file

spec.helmVersion

v3

Helm version to use (v2 or v3)

spec.bootstrap

False

Set to True if this chart is needed to bootstrap the cluster (Cloud Controller Manager, etc)

spec.set

Override simple default Chart values. These take precedence over options set via valuesContent.

--set / --set-string

spec.jobImage

Specify the image to use when installing the helm chart. E.g. rancher/klipper-helm:v0.3.0 .

spec.backOffLimit

1000

Specify the number of retries before considering a job failed.

spec.timeout

300s

Timeout for Helm operations, as a duration string (300s, 10m, 1h, etc)

--timeout

spec.failurePolicy

reinstall

Set to abort which case the Helm operation is aborted, pending manual intervention by the operator.

spec.authSecret

Reference to Secret of type kubernetes.io/basic-auth holding Basic auth credentials for the Chart repo.

spec.authPassCredentials

false

Pass Basic auth credentials to all domains.

--pass-credentials

spec.dockerRegistrySecret

Reference to Secret of type kubernetes.io/dockerconfigjson holding Docker auth credentials for the OCI-based registry acting as the Chart repo.

spec.valuesContent

Override complex default Chart values via YAML file content

--values

spec.chartContent

Base64-encoded chart archive .tgz - overrides spec.chart

CHART

Customizing Packaged Components with HelmChartConfig

To allow overriding values for packaged components that are deployed as HelmCharts (such as Canal, CoreDNS, Nginx-Ingress, etc), RKE2 supports customizing deployments via a HelmChartConfig resources. The HelmChartConfig resource must match the name and namespace of its corresponding HelmChart, and supports providing additional valuesContent, which is passed to the helm command as an additional value file.

HelmChart spec.set values override HelmChart and HelmChartConfig spec.valuesContent settings.

For example, to customize the packaged CoreDNS configuration, you can create a file named /var/lib/rancher/rke2/server/manifests/rke2-coredns-config.yaml and populate it with the following content:

apiVersion: helm.cattle.io/v1
kind: HelmChartConfig
metadata:
  name: rke2-coredns
  namespace: kube-system
spec:
  valuesContent: |-
    image: coredns/coredns
    imageTag: v1.7.1

You can find all the packaged Helm charts including their documentation and default values in the RKE2 charts repository.