---
title: K3s Cluster Configuration Reference
---
This section covers the configuration options that are available in Rancher for a new or existing K3s Kubernetes cluster.
## Overview
You can configure the Kubernetes options one of two ways:
- [Rancher UI](#configuration-options-in-the-rancher-ui): Use the Rancher UI to select options that are commonly customized when setting up a Kubernetes cluster.
- [Cluster Config File](#cluster-config-file-reference): Instead of using the Rancher UI to choose Kubernetes options for the cluster, advanced users can create a K3s config file. Using a config file allows you to set any of the [options](https://rancher.com/docs/k3s/latest/en/installation/install-options/) available in an K3s installation.
## Editing Clusters in the Rancher UI
The Rancher UI provides two ways to edit a cluster:
1. With a form.
1. With YAML.
### Editing Clusters with a Form
The form covers the most frequently needed options for clusters.
To edit your cluster,
1. Click **☰ > Cluster Management**.
1. Go to the cluster you want to configure and click **⋮ > Edit Config**.
### Editing Clusters in YAML
For a complete reference of configurable options for K3s clusters in YAML, see the [K3s documentation.](https://rancher.com/docs/k3s/latest/en/installation/install-options/)
To edit your cluster with YAML:
1. Click **☰ > Cluster Management**.
1. Go to the cluster you want to configure and click **⋮ > Edit as YAML**.
1. Edit the RKE options under the `rkeConfig` directive.
## Configuration Options in the Rancher UI
### Machine Pool Configuration
This subsection covers generic machine pool configurations. For specific infrastructure provider configurations, refer to the following:
- [Azure](../downstream-cluster-configuration/machine-configuration/azure.md)
- [DigitalOcean](../downstream-cluster-configuration/machine-configuration/digitalocean.md)
- [EC2](../downstream-cluster-configuration/machine-configuration/amazon-ec2.md)
##### Pool Name
The name of the machine pool.
##### Machine Count
The number of machines in the pool.
##### Roles
Option to assign etcd, control plane, and worker roles to nodes.
#### Advanced
##### Auto Replace
The amount of time nodes can be unreachable before they are automatically deleted and replaced.
##### Drain Before Delete
Enables draining nodes by evicting all pods before the node is deleted.
##### Kubernetes Node Labels
Add [labels](https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/) to nodes to help with organization and object selection.
For details on label syntax requirements, see the [Kubernetes documentation.](https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set)
##### Taints
Add [taints](https://kubernetes.io/docs/concepts/configuration/taint-and-toleration/) to nodes, to prevent pods from being scheduled to or executed on the nodes, unless the pods have matching tolerations.
### Cluster Configuration
#### Basics
##### Kubernetes Version
The version of Kubernetes installed on your cluster nodes. Rancher packages its own version of Kubernetes based on [hyperkube](https://github.com/rancher/hyperkube).
For more detail, see [Upgrading Kubernetes](../../../getting-started/installation-and-upgrade/upgrade-and-roll-back-kubernetes.md).
##### Pod Security Admission Configuration Template
The default [pod security admission configuration template](../../../how-to-guides/new-user-guides/authentication-permissions-and-global-configuration/psa-config-templates.md) for the cluster.
##### Encrypt Secrets
Option to enable or disable secrets encryption. When enabled, secrets will be encrypted using a AES-CBC key. If disabled, any previously secrets will not be readable until encryption is enabled again. Refer to the [K3s documentation](https://rancher.com/docs/k3s/latest/en/advanced/#secrets-encryption-config-experimental) for details.
##### Project Network Isolation
If your network provider allows project network isolation, you can choose whether to enable or disable inter-project communication.
##### SELinux
Option to enable or disable [SELinux](https://rancher.com/docs/k3s/latest/en/advanced/#selinux-support) support.
##### CoreDNS
By default, [CoreDNS](https://coredns.io/) is installed as the default DNS provider. If CoreDNS is not installed, an alternate DNS provider must be installed yourself. Refer to the [K3s documentation](https://rancher.com/docs/k3s/latest/en/networking/#coredns) for details..
##### Klipper Service LB
Option to enable or disable the [Klipper](https://github.com/rancher/klipper-lb) service load balancer. Refer to the [K3s documentation](https://rancher.com/docs/k3s/latest/en/networking/#service-load-balancer) for details.
##### Traefik Ingress
Option to enable or disable the [Traefik](https://traefik.io/) HTTP reverse proxy and load balancer. For more details and configuration options, see the [K3s documentation](https://rancher.com/docs/k3s/latest/en/networking/#traefik-ingress-controller).
##### Local Storage
Option to enable or disable [local storage](https://rancher.com/docs/k3s/latest/en/storage/) on the node(s).
##### Metrics Server
Option to enable or disable the [metrics server](https://github.com/kubernetes-incubator/metrics-server). If enabled, ensure port 10250 is opened for inbound TCP traffic.
#### Add-On Config
Additional Kubernetes manifests, managed as a [Add-on](https://kubernetes.io/docs/concepts/cluster-administration/addons/), to apply to the cluster on startup. Refer to the [K3s documentation](https://rancher.com/docs/k3s/latest/en/helm/#automatically-deploying-manifests-and-helm-charts) for details.
#### Agent Environment Vars
Option to set environment variables for [K3s agents](https://rancher.com/docs/k3s/latest/en/architecture/). The environment variables can be set using key value pairs. Refer to the [K3 documentation](https://rancher.com/docs/k3s/latest/en/installation/install-options/agent-config/) for more details.
#### etcd
##### Automatic Snapshots
Option to enable or disable recurring etcd snapshots. If enabled, users have the option to configure the frequency of snapshots. For details, refer to the [K3s documentation](https://rancher.com/docs/k3s/latest/en/backup-restore/#creating-snapshots).
##### Metrics
Option to choose whether to expose etcd metrics to the public or only within the cluster.
#### Networking
##### Cluster CIDR
IPv4/IPv6 network CIDRs to use for pod IPs (default: 10.42.0.0/16).
##### Service CIDR
IPv4/IPv6 network CIDRs to use for service IPs (default: 10.43.0.0/16).
##### Cluster DNS
IPv4 Cluster IP for coredns service. Should be in your service-cidr range (default: 10.43.0.10).
##### Cluster Domain
Select the domain for the cluster. The default is `cluster.local`.
##### NodePort Service Port Range
Option to change the range of ports that can be used for [NodePort services](https://kubernetes.io/docs/concepts/services-networking/service/#nodeport). The default is `30000-32767`.
##### Truncate Hostnames
Option to truncate hostnames to 15 characters or less. You can only set this field during the initial creation of the cluster. You can't enable or disable the 15 character limit after cluster creation.
This setting only affects machine-provisioned clusters. Since custom clusters set hostnames during their own node creation process, which occurs outside of Rancher, this field doesn't restrict custom cluster hostname length.
Truncating hostnames in a cluster improves compatibility with Windows-based systems. Although Kubernetes allows hostnames up to 63 characters in length, systems that use NetBIOS restrict hostnames to 15 characters or less.
##### TLS Alternate Names
Add hostnames or IPv4/IPv6 addresses as Subject Alternative Names on the server TLS cert.
##### Authorized Cluster Endpoint
Authorized Cluster Endpoint can be used to directly access the Kubernetes API server, without requiring communication through Rancher.
For more detail on how an authorized cluster endpoint works and why it is used, refer to the [architecture section.](../../../reference-guides/rancher-manager-architecture/communicating-with-downstream-user-clusters.md#4-authorized-cluster-endpoint)
We recommend using a load balancer with the authorized cluster endpoint. For details, refer to the [recommended architecture section.](../../rancher-manager-architecture/architecture-recommendations.md#architecture-for-an-authorized-cluster-endpoint-ace)
#### Registries
Select the image repository to pull Rancher images from. For more details and configuration options, see the [K3s documentation](https://rancher.com/docs/k3s/latest/en/installation/private-registry/).
#### Upgrade Strategy
##### Control Plane Concurrency
Select how many nodes can be upgraded at the same time. Can be a fixed number or percentage.
##### Worker Concurrency
Select how many nodes can be upgraded at the same time. Can be a fixed number or percentage.
##### Drain Nodes (Control Plane)
Option to remove all pods from the node prior to upgrading.
##### Drain Nodes (Worker Nodes)
Option to remove all pods from the node prior to upgrading.
#### Advanced
Option to set kubelet options for different nodes. For available options, refer to the [Kubernetes documentation](https://kubernetes.io/docs/reference/command-line-tools-reference/kubelet/).
## Cluster Config File Reference
Editing clusters in YAML allows you to set configurations that are already listed in [Configuration Options in the Rancher UI](#configuration-options-in-the-rancher-ui), as well as set Rancher-specific parameters.
Example Cluster Config File Snippet
```yaml
apiVersion: provisioning.cattle.io/v1
kind: Cluster
spec:
cloudCredentialSecretName: cattle-global-data:cc-fllv6
clusterAgentDeploymentCustomization: {}
fleetAgentDeploymentCustomization: {}
kubernetesVersion: v1.26.7+k3s1
localClusterAuthEndpoint: {}
rkeConfig:
additionalManifest: ""
chartValues: {}
etcd:
snapshotRetention: 5
snapshotScheduleCron: 0 */5 * * *
machineGlobalConfig:
disable-apiserver: false
disable-cloud-controller: false
disable-controller-manager: false
disable-etcd: false
disable-kube-proxy: false
disable-network-policy: false
disable-scheduler: false
etcd-expose-metrics: false
kube-apiserver-arg:
- audit-policy-file=/etc/rancher/k3s/user-audit-policy.yaml
- audit-log-path=/etc/rancher/k3s/user-audit.logs
profile: null
secrets-encryption: false
machinePools:
- controlPlaneRole: true
etcdRole: true
machineConfigRef:
kind: Amazonec2Config
name: nc-test-pool1-pwl5h
name: pool1
quantity: 1
unhealthyNodeTimeout: 0s
workerRole: true
machineSelectorConfig:
- config:
docker: false
protect-kernel-defaults: false
selinux: false
machineSelectorFiles:
- fileSources:
- configMap:
name: ''
secret:
name: audit-policy
items:
- key: audit-policy
path: /etc/rancher/k3s/user-audit-policy.yaml
machineLabelSelector:
matchLabels:
rke.cattle.io/control-plane-role: 'true'
registries: {}
upgradeStrategy:
controlPlaneConcurrency: '1'
controlPlaneDrainOptions:
deleteEmptyDirData: true
disableEviction: false
enabled: false
force: false
gracePeriod: -1
ignoreDaemonSets: true
ignoreErrors: false
postDrainHooks: null
preDrainHooks: null
skipWaitForDeleteTimeoutSeconds: 0
timeout: 120
workerConcurrency: '1'
workerDrainOptions:
deleteEmptyDirData: true
disableEviction: false
enabled: false
force: false
gracePeriod: -1
ignoreDaemonSets: true
ignoreErrors: false
postDrainHooks: null
preDrainHooks: null
skipWaitForDeleteTimeoutSeconds: 0
timeout: 120
```
### additionalManifest
Specify additional manifests to deliver to the control plane nodes.
The value is a String, and will be placed at the path `/var/lib/rancher/k3s/server/manifests/rancher/addons.yaml` on target nodes.
Example:
```yaml
additionalManifest: |-
apiVersion: v1
kind: Namespace
metadata:
name: name-xxxx
```
:::note
If you want to customize system charts, you should use the `chartValues` field as described below.
Alternatives, such as using a HelmChartConfig to customize the system charts via `additionalManifest`, can cause unexpected behavior, due to having multiple HelmChartConfigs for the same chart.
:::
### chartValues
Specify the values for the system charts installed by K3s.
For more information about how K3s manges packaged components, please refer to [K3s documentation](https://docs.k3s.io/installation/packaged-components).
Example:
```yaml
chartValues:
chart-name:
key: value
```
### machineGlobalConfig
Specify K3s configurations. Any configuration change made here will apply to every node. The configuration options available in the [standalone version of k3s](https://docs.k3s.io/cli/server) can be applied here.
Example:
```yaml
machineGlobalConfig:
etcd-arg:
- key1=value1
- key2=value2
```
To make it easier to put files on nodes beforehand, Rancher expects the following values to be included in the configuration, while K3s expects the values to be entered as file paths:
- private-registry
- flannel-conf
Rancher delivers the files to the path `/var/lib/rancher/k3s/etc/config-files/