k3s agent

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

Note that servers also run an agent, so all flags listed on this page are also valid for use on servers.

Options are documented on this page as CLI flags, but can also be passed as configuration file options. See the Configuration File documentation for more information on using YAML configuration files.

Logging

Flag	Default	Description
-v value	0	Number for the log level verbosity
--vmodule value	N/A	Comma-separated list of FILE_PATTERN=LOG_LEVEL settings for file-filtered logging
--log value, -l value	N/A	Log to file
--alsologtostderr	N/A	Log to standard error as well as file (if set)

Cluster Options

Flag	Environment Variable	Description
--token value, -t value	K3S_TOKEN	Token to use for authentication
--token-file value	K3S_TOKEN_FILE	Token file to use for authentication
--server value, -s value	K3S_URL	Server to connect to

Data

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

Node

Flag	Environment Variable	Description
--node-name value	K3S_NODE_NAME	Node name
--with-node-id	N/A	Append id to node name
--node-label value	N/A	Registering and starting kubelet with set of labels
--node-taint value	N/A	Registering kubelet with set of taints
--protect-kernel-defaults	N/A	Kernel tuning behavior. If set, error if kernel tunables are different from kubelet defaults.
--selinux	K3S_SELINUX	Enable SELinux in containerd
--lb-server-port value	K3S_LB_SERVER_PORT	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)

Runtime

Flag	Default	Description
--container-runtime-endpoint value	N/A	Disable embedded containerd and use the CRI socket at the given path; when used with --docker this sets the cri-docker socket path
--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

Flag	Environment Variable	Description
--node-ip value, -i value	N/A	IP address to advertise for node
--node-external-ip value	N/A	External IP address to advertise for node
--resolv-conf value	K3S_RESOLV_CONF	Kubelet resolv.conf file
--flannel-iface value	N/A	Override default flannel interface
--flannel-conf value	N/A	Override default flannel config file
--flannel-cni-conf value	N/A	Override default flannel cni config file

Customized Flags

Flag	Description
--kubelet-arg value	Customized flag for kubelet process
--kube-proxy-arg value	Customized flag for kube-proxy process

Experimental

Flag	Description
--rootless	Run rootless
--docker	Use cri-dockerd instead of containerd
--prefer-bundled-bin	Prefer bundled userspace binaries over host binaries

Deprecated

Flag	Environment Variable	Description
--no-flannel	N/A	Use --flannel-backend=none
--cluster-secret value	K3S_CLUSTER_SECRET	Use --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 FILE_PATTERN=LOG_LEVEL 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")
   --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]
   --protect-kernel-defaults                  (agent/node) Kernel tuning behavior. If set, error if kernel tunables are different than kubelet defaults.
   --container-runtime-endpoint value         (agent/runtime) Disable embedded containerd and use the CRI socket at the given path; when used with --docker this sets the docker socket path
   --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
   --rootless                                 (experimental) Run rootless
   --prefer-bundled-bin                       (experimental) Prefer bundled userspace binaries over host binaries
   --docker                                   (agent/runtime) (experimental) Use cri-dockerd instead of containerd