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K3s Agent Configuration

In this section, you'll learn how to configure the K3s agent.

Logging

FlagDefaultDescription
-v value0Number for the log level verbosity
--vmodule valueN/AComma-separated list of pattern=N settings for file-filtered logging
--log value, -l valueN/ALog to file
--alsologtostderrN/ALog to standard error as well as file (if set)

Cluster Options

FlagEnvironment VariableDescription
--token value, -t valueK3S_TOKENToken to use for authentication
--token-file valueK3S_TOKEN_FILEToken file to use for authentication
--server value, -s valueK3S_URLServer to connect to

Data

FlagDefaultDescription
--data-dir value, -d value"/var/lib/rancher/k3s"Folder to hold state

Node

FlagEnvironment VariableDescription
--node-name valueK3S_NODE_NAMENode name
--with-node-idN/AAppend id to node name
--node-label valueN/ARegistering and starting kubelet with set of labels
--node-taint valueN/ARegistering kubelet with set of taints

Runtime

FlagDefaultDescription
--container-runtime-endpoint valueN/ADisable embedded containerd and use alternative CRI implementation
--pause-image value"docker.io/rancher/pause:3.1"Customized pause image for containerd or docker sandbox
--private-registry value"/etc/rancher/k3s/registries.yaml"Private registry configuration file

Networking

FlagEnvironment VariableDescription
--node-ip value, -i valueN/AIP address to advertise for node
--node-external-ip valueN/AExternal IP address to advertise for node
--resolv-conf valueK3S_RESOLV_CONFKubelet resolv.conf file
--flannel-iface valueN/AOverride default flannel interface
--flannel-conf valueN/AOverride default flannel config file
--flannel-cni-conf valueN/AOverride default flannel cni config file

Customized Flags

FlagDescription
--kubelet-arg valueCustomized flag for kubelet process
--kube-proxy-arg valueCustomized flag for kube-proxy process

Experimental

FlagDescription
--rootlessRun rootless
--dockerUse cri-dockerd instead of containerd

Deprecated

FlagEnvironment VariableDescription
--no-flannelN/AUse --flannel-backend=none
--cluster-secret valueK3S_CLUSTER_SECRETUse --token

Node Labels and Taints for Agents

K3s agents can be configured with the options --node-label and --node-taint which adds a label and taint to the kubelet. The two options only add labels and/or taints at registration time, so they can only be added once and not changed after that again by running K3s commands.

Below is an example showing how to add labels and a taint:

     --node-label foo=bar \
--node-label hello=world \
--node-taint key1=value1:NoExecute

If you want to change node labels and taints after node registration you should use kubectl. Refer to the official Kubernetes documentation for details on how to add taints and node labels.

K3s Agent CLI Help

If an option appears in brackets below, for example [$K3S_URL], it means that the option can be passed in as an environment variable of that name.

NAME:
k3s agent - Run node agent

USAGE:
k3s agent [OPTIONS]

OPTIONS:
--config FILE, -c FILE (config) Load configuration from FILE (default: "/etc/rancher/k3s/config.yaml") [$K3S_CONFIG_FILE]
--debug (logging) Turn on debug logs [$K3S_DEBUG]
-v value (logging) Number for the log level verbosity (default: 0)
--vmodule value (logging) Comma-separated list of pattern=N settings for file-filtered logging
--log value, -l value (logging) Log to file
--alsologtostderr (logging) Log to standard error as well as file (if set)
--token value, -t value (cluster) Token to use for authentication [$K3S_TOKEN]
--token-file value (cluster) Token file to use for authentication [$K3S_TOKEN_FILE]
--server value, -s value (cluster) Server to connect to [$K3S_URL]
--data-dir value, -d value (agent/data) Folder to hold state (default: "/var/lib/rancher/k3s")
--node-name value (agent/node) Node name [$K3S_NODE_NAME]
--with-node-id (agent/node) Append id to node name
--node-label value (agent/node) Registering and starting kubelet with set of labels
--node-taint value (agent/node) Registering kubelet with set of taints
--image-credential-provider-bin-dir value (agent/node) The path to the directory where credential provider plugin binaries are located (default: "/var/lib/rancher/credentialprovider/bin")
--image-credential-provider-config value (agent/node) The path to the credential provider plugin config file (default: "/var/lib/rancher/credentialprovider/config.yaml")
--container-runtime-endpoint value (agent/runtime) Disable embedded containerd and use alternative CRI implementation
--pause-image value (agent/runtime) Customized pause image for containerd or docker sandbox (default: "rancher/mirrored-pause:3.6")
--snapshotter value (agent/runtime) Override default containerd snapshotter (default: "overlayfs")
--private-registry value (agent/runtime) Private registry configuration file (default: "/etc/rancher/k3s/registries.yaml")
--node-ip value, -i value (agent/networking) IPv4/IPv6 addresses to advertise for node
--node-external-ip value (agent/networking) IPv4/IPv6 external IP addresses to advertise for node
--resolv-conf value (agent/networking) Kubelet resolv.conf file [$K3S_RESOLV_CONF]
--flannel-iface value (agent/networking) Override default flannel interface
--flannel-conf value (agent/networking) Override default flannel config file
--flannel-cni-conf value (agent/networking) Override default flannel cni config file
--kubelet-arg value (agent/flags) Customized flag for kubelet process
--kube-proxy-arg value (agent/flags) Customized flag for kube-proxy process
--protect-kernel-defaults (agent/node) Kernel tuning behavior. If set, error if kernel tunables are different than kubelet defaults.
--rootless (experimental) Run rootless
--selinux (agent/node) Enable SELinux in containerd [$K3S_SELINUX]
--lb-server-port value (agent/node) Local port for supervisor client load-balancer. If the supervisor and apiserver are not colocated an additional port 1 less than this port will also be used for the apiserver client load-balancer. (default: 6444) [$K3S_LB_SERVER_PORT]
--docker (deprecated) Use docker instead of containerd
--no-flannel (deprecated) use --flannel-backend=none
--cluster-secret value (deprecated) use --token [$K3S_CLUSTER_SECRET]