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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. 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

FieldDefaultDescriptionHelm Argument / Flag Equivalent
metadata.nameHelm Chart nameNAME
spec.chartHelm Chart name in repository, or complete HTTPS URL to chart archive (.tgz)CHART
spec.targetNamespacedefaultHelm Chart target namespace--namespace
spec.createNamespacefalseCreate target namespace if not present--create-namespace
spec.versionHelm Chart version (when installing from repository)--version
spec.repoHelm Chart repository URL--repo
spec.repoCAVerify certificates of HTTPS-enabled servers using this CA bundle. Should be a string containing one or more PEM-encoded CA Certificates.--ca-file
spec.repoCAConfigMapReference to a ConfigMap containing CA Certificates to be be trusted by Helm. Can be used along with or instead of repoCA--ca-file
spec.helmVersionv3Helm version to use (v2 or v3)
spec.bootstrapFalseSet to True if this chart is needed to bootstrap the cluster (Cloud Controller Manager, etc)
spec.setOverride simple default Chart values. These take precedence over options set via valuesContent.--set / --set-string
spec.jobImageSpecify the image to use when installing the helm chart. E.g. rancher/klipper-helm:v0.3.0 .
spec.backOffLimit1000Specify the number of retries before considering a job failed.
spec.timeout300sTimeout for Helm operations, as a duration string (300s, 10m, 1h, etc)--timeout
spec.failurePolicyreinstallSet to abort which case the Helm operation is aborted, pending manual intervention by the operator.
spec.authSecretReference to Secret of type kubernetes.io/basic-auth holding Basic auth credentials for the Chart repo.
spec.authPassCredentialsfalsePass Basic auth credentials to all domains.--pass-credentials
spec.dockerRegistrySecretReference to Secret of type kubernetes.io/dockerconfigjson holding Docker auth credentials for the OCI-based registry acting as the Chart repo.
spec.valuesContentOverride complex default Chart values via YAML file content--values
spec.chartContentBase64-encoded chart archive .tgz - overrides spec.chartCHART

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.

note

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.