Configuration options#
Using a configuration file#
k0s can be installed without a config file. In that case the default configuration will be used. You can, though, create and run your own non-default configuration (used by the k0s controller nodes).
k0s supports providing only partial configurations. In case of partial configuration is provided, k0s will use the defaults for any missing values.
-
Generate a yaml config file that uses the default settings.
mkdir -p /etc/k0s k0s config create > /etc/k0s/k0s.yaml -
Modify the new yaml config file according to your needs, refer to Configuration file reference below. You can remove the default values if wanted as k0s supports partial configs too.
-
Install k0s with your new config file.
sudo k0s install controller -c /etc/k0s/k0s.yaml -
If you need to modify your existing configuration later on, you can change your config file also when k0s is running, but remember to restart k0s to apply your configuration changes.
sudo k0s stop sudo k0s start
Configuring k0s via k0sctl#
k0sctl can deploy your configuration options at cluster creation time. Your
options should be placed in the spec.k0s.config section of the k0sctl's
configuration file. See the section on how to install k0s via
k0sctl and the k0sctl README for more information.
Configuration file reference#
CAUTION: As many of the available options affect items deep in the stack, you should fully understand the correlation between the configuration file components and your specific environment before making any changes.
A YAML config file follows, with defaults as generated by the k0s config create command:
apiVersion: k0s.k0sproject.io/v1beta1
kind: ClusterConfig
metadata:
name: k0s
spec:
api:
address: 192.168.68.104
externalAddress: my-lb-address.example.com
k0sApiPort: 9443
port: 6443
sans:
- 192.168.68.104
controllerManager: {}
extensions:
helm:
concurrencyLevel: 5
charts: null
repositories: null
storage:
create_default_storage_class: false
type: external_storage
installConfig:
users:
etcdUser: etcd
kineUser: kube-apiserver
konnectivityUser: konnectivity-server
kubeAPIserverUser: kube-apiserver
kubeSchedulerUser: kube-scheduler
konnectivity:
adminPort: 8133
agentPort: 8132
network:
calico: null
clusterDomain: cluster.local
dualStack: {}
kubeProxy:
metricsBindAddress: 0.0.0.0:10249
mode: iptables
kuberouter:
autoMTU: true
hairpin: Enabled
ipMasq: false
metricsPort: 8080
mtu: 0
peerRouterASNs: ""
peerRouterIPs: ""
extraArgs:
nodeLocalLoadBalancing:
enabled: false
envoyProxy:
apiServerBindPort: 7443
konnectivityServerBindPort: 7132
type: EnvoyProxy
podCIDR: 10.244.0.0/16
provider: kuberouter
serviceCIDR: 10.96.0.0/12
scheduler: {}
storage:
etcd:
externalCluster: null
peerAddress: 192.168.68.104
type: etcd
telemetry:
enabled: true
featureGates:
- name: feature_XXX
enabled: true
components: ["kubelet", "kube-api", "kube-scheduler"]
- name: feature_YYY
enabled: true
-
name: feature_ZZZ
enabled: false
spec Key Detail#
spec.api#
| Element | Description |
|---|---|
externalAddress |
The loadbalancer address (for k0s controllers running behind a loadbalancer). Configures all cluster components to connect to this address and also configures this address for use when joining new nodes to the cluster. |
address |
Local address on which to bind an API. Also serves as one of the addresses pushed on the k0s create service certificate on the API. Defaults to first non-local address found on the node. |
sans |
List of additional addresses to push to API servers serving the certificate. |
extraArgs |
Map of key-values (strings) for any extra arguments to pass down to Kubernetes api-server process. |
port¹ |
Custom port for kube-api server to listen on (default: 6443) |
k0sApiPort¹ |
Custom port for k0s-api server to listen on (default: 9443) |
¹ If port and k0sApiPort are used with the externalAddress element, the loadbalancer serving at externalAddress must listen on the same ports.
spec.storage#
| Element | Description |
|---|---|
type |
Type of the data store (valid values:etcd or kine). Note: Type etcd will cause k0s to create and manage an elastic etcd cluster within the controller nodes. |
etcd.peerAddress |
Node address used for etcd cluster peering. |
etcd.extraArgs |
Map of key-values (strings) for any extra arguments to pass down to etcd process. |
kine.dataSource |
kine datasource URL. |
etcd.externalCluster |
Configuration when etcd is externally managed, i.e. running on dedicated nodes. See spec.storage.etcd.externalCluster |
spec.storage.etcd.externalCluster#
k0s can also work with externally managed Etcd cluster. If this is configured, k0s will NOT set up etcd, it has to be managed manually.
| Element | Description |
|---|---|
endpoints |
Array of Etcd endpoints to use. |
etcdPrefix |
Prefix to use for this cluster. The same external Etcd cluster can be used for several k0s clusters, each prefixed with unique prefix to store data with. |
caFile |
CaFile is the host path to a file with Etcd cluster CA certificate. |
clientCertFile |
ClientCertFile is the host path to a file with TLS certificate for etcd client. |
clientKeyFile |
ClientKeyFile is the host path to a file with TLS key for etcd client. |
spec.network#
| Element | Description |
|---|---|
provider |
Network provider (valid values: calico, kuberouter, or custom). For custom, you can push any network provider (default: kuberouter). Be aware that it is your responsibility to configure all of the CNI-related setups, including the CNI provider itself and all necessary host levels setups (for example, CNI binaries). Note: Once you initialize the cluster with a network provider the only way to change providers is through a full cluster redeployment. |
podCIDR |
Pod network CIDR to use in the cluster. |
serviceCIDR |
Network CIDR to use for cluster VIP services. |
clusterDomain |
Cluster Domain to be passed to the kubelet and the coredns configuration. |
spec.network.calico#
| Element | Description |
|---|---|
mode |
vxlan (default), ipip or bird |
overlay |
Overlay mode: Always (default), CrossSubnet or Never (requires mode=vxlan to disable calico overlay-network). |
vxlanPort |
The UDP port for VXLAN (default: 4789). |
vxlanVNI |
The virtual network ID for VXLAN (default: 4096). |
mtu |
MTU for overlay network (default: 0, which causes Calico to detect optimal MTU during bootstrap). |
wireguard |
Enable wireguard-based encryption (default: false). Your host system must be wireguard ready (refer to the Calico documentation for details). |
flexVolumeDriverPath |
The host path for Calicos flex-volume-driver(default: /usr/libexec/k0s/kubelet-plugins/volume/exec/nodeagent~uds). Change this path only if the default path is unwriteable (refer to Project Calico Issue #2712 for details). Ideally, you will pair this option with a custom volumePluginDir in the profile you use for your worker nodes. |
ipAutodetectionMethod |
Use to force Calico to pick up the interface for pod network inter-node routing (default: "", meaning not set, so that Calico will instead use its defaults). For more information, refer to the Calico documentation. |
envVars |
Map of key-values (strings) for any calico-node environment variable. |
spec.network.calico.envVars#
Environment variable's value must be string, e.g.:
spec:
network:
provider: calico
calico:
envVars:
TEST_BOOL_VAR: "true"
TEST_INT_VAR: "42"
TEST_STRING_VAR: test
K0s runs Calico with some predefined vars, which can be overwritten by setting new value in spec.network.calico.envVars:
CALICO_IPV4POOL_CIDR: "{{ spec.network.podCIDR }}"
CALICO_DISABLE_FILE_LOGGING: "true"
FELIX_DEFAULTENDPOINTTOHOSTACTION: "ACCEPT"
FELIX_LOGSEVERITYSCREEN: "info"
FELIX_HEALTHENABLED: "true"
FELIX_PROMETHEUSMETRICSENABLED: "true"
FELIX_FEATUREDETECTOVERRIDE: "ChecksumOffloadBroken=true"
FELIX_FEATUREDETECTOVERRIDE: ChecksumOffloadBroken=true disables VXLAN offloading because of projectcalico/calico#4727.
In SingleStack mode there are additional vars:
FELIX_IPV6SUPPORT: "false"
In DualStack mode there are additional vars:
CALICO_IPV6POOL_NAT_OUTGOING: "true"
FELIX_IPV6SUPPORT: "true"
IP6: "autodetect"
CALICO_IPV6POOL_CIDR: "{{ spec.network.dualStack.IPv6podCIDR }}"
spec.network.kuberouter#
| Element | Description |
|---|---|
autoMTU |
Autodetection of used MTU (default: true). |
mtu |
Override MTU setting, if autoMTU must be set to false). |
metricsPort |
Kube-router metrics server port. Set to 0 to disable metrics (default: 8080). |
peerRouterIPs |
DEPRECATED: Use extraArgs with peerRouterIPs instead. Comma-separated list of global peer addresses. |
peerRouterASNs |
DEPRECATED: Use extraArgs with peerRouterASNs instead. Comma-separated list of global peer ASNs. |
hairpin |
Hairpin mode, supported modes Enabled: enabled cluster wide, Allowed: must be allowed per service using annotations, Disabled: doesn't work at all (default: Enabled) |
hairpinMode |
Deprecated Use hairpin instead. If both hairpin and hairpinMode are defined, this is ignored. If only hairpinMode is configured explicitly activates hairpinMode (https://github.com/cloudnativelabs/kube-router/blob/master/docs/user-guide.md#hairpin-mode). |
ipMasq |
IP masquerade for traffic originating from the pod network, and destined outside of it (default: false) |
extraArgs |
Extra arguments to pass to kube-router. Can be also used to override any k0s managed args. For reference, see kube-router documentation. (default: empty) |
Note: Kube-router allows many networking aspects to be configured per node, service, and pod (for more information, refer to the Kube-router user guide).
spec.network.kubeProxy#
| Element | Description |
|---|---|
disabled |
Disable kube-proxy altogether (default: false). |
mode |
Kube proxy operating mode, supported modes iptables, ipvs, userspace (default: iptables) |
iptables |
Kube proxy iptables settings |
ipvs |
Kube proxy ipvs settings |
nodePortAddresses |
Kube proxy nodePortAddresses |
Default kube-proxy iptables settings:
iptables:
masqueradeAll: false
masqueradeBit: null
minSyncPeriod: 0s
syncPeriod: 0s
Default kube-proxy ipvs settings:
ipvs:
excludeCIDRs: null
minSyncPeriod: 0s
scheduler: ""
strictARP: false
syncPeriod: 0s
tcpFinTimeout: 0s
tcpTimeout: 0s
udpTimeout: 0s
spec.network.nodeLocalLoadBalancing#
Configuration options related to k0s's node-local load balancing feature.
| Element | Description |
|---|---|
enabled |
Indicates if node-local load balancing should be used to access Kubernetes API servers from worker nodes. Default: false. |
type |
The type of the node-local load balancer to deploy on worker nodes. Default: EnvoyProxy. (This is the only option for now.) |
envoyProxy |
Configuration options related to the "EnvoyProxy" type of load balancing. |
spec.network.nodeLocalLoadBalancing.envoyProxy#
Configuration options required for using Envoy as the backing implementation for node-local load balancing.
Note: This type of load balancing is not supported on ARMv7 workers.
| Element | Description |
|---|---|
image |
The OCI image that's being used for the Envoy Pod. |
imagePullPolicy |
The pull policy being used used for the Envoy Pod. Defaults to spec.images.default_pull_policy if omitted. |
apiServerBindPort |
Port number on which to bind the Envoy load balancer for the Kubernetes API server to on a worker's loopback interface. Default: 7443. |
konnectivityServerBindPort |
Port number on which to bind the Envoy load balancer for the konnectivity server to on a worker's loopback interface. Default: 7132. |
spec.controllerManager#
| Element | Description |
|---|---|
extraArgs |
Map of key-values (strings) for any extra arguments you want to pass down to the Kubernetes controller manager process. |
spec.scheduler#
| Element | Description |
|---|---|
extraArgs |
Map of key-values (strings) for any extra arguments you want to pass down to Kubernetes scheduler process. |
spec.workerProfiles#
Worker profiles are used to manage worker-specific configuration in a
centralized manner. A ConfigMap is generated for each worker profile. Based on
the --profile argument given to the k0s worker, the configuration in the
corresponding ConfigMap is is picked up during startup.
The worker profiles are defined as an array. Each element has following properties:
| Property | Description |
|---|---|
name |
String; name to use as profile selector for the worker process |
values |
Object; Kubelet configuration overrides, see below for details |
spec.workerProfiles[].values (Kubelet configuration overrides)#
The Kubelet configuration overrides of a profile override the defaults defined by k0s.
Note that there are several fields that cannot be overridden:
clusterDNSclusterDomainapiVersionkindstaticPodURL
Configuration examples#
Custom volumePluginDir#
spec:
workerProfiles:
- name: custom-pluginDir
values:
volumePluginDir: /var/libexec/k0s/kubelet-plugins/volume/exec
Eviction Policy#
spec:
workerProfiles:
- name: custom-eviction
values:
evictionHard:
memory.available: "500Mi"
nodefs.available: "1Gi"
imagefs.available: "100Gi"
evictionMinimumReclaim:
memory.available: "0Mi"
nodefs.available: "500Mi"
imagefs.available: "2Gi"
Unsafe Sysctls#
spec:
workerProfiles:
- name: custom-eviction
values:
allowedUnsafeSysctls:
- fs.inotify.max_user_instances
spec.featureGates#
Available components are:
- kube-apiserver
- kube-controller-manager
- kubelet
- kube-scheduler
- kube-proxy
If components are omitted, propagates to all kube components.
Modifies extraArgs.
Examples#
Generic feature gates example#
spec:
featureGates:
- name: feature-gate-0
enabled: true
components: ["kube-apiserver", "kube-controller-manager", "kubelet", "kube-scheduler"]
- name: feature-gate-1
enabled: true
- name: feature-gate-2
enabled: false
Kubelet feature gates example#
The below is an example of a k0s config with feature gates enabled:
spec:
featureGates:
- name: DevicePlugins
enabled: true
components: ["kubelet"]
- name: Accelerators
enabled: true
components: ["kubelet"]
- name: AllowExtTrafficLocalEndpoints
enabled: false
spec.images#
Nodes under the images key all have the same basic structure:
spec:
images:
coredns:
image: quay.io/coredns/coredns
version: v1.7.0
If you want the list of default images and their versions to be included, use k0s config create --include-images.
Available keys#
spec.images.konnectivityspec.images.metricsserverspec.images.kubeproxyspec.images.corednsspec.images.pausespec.images.calico.cnispec.images.calico.flexvolumespec.images.calico.nodespec.images.calico.kubecontrollersspec.images.kuberouter.cnispec.images.kuberouter.cniInstallerspec.images.repository¹
¹ If spec.images.repository is set and not empty, every image will be pulled from images.repository
If spec.images.default_pull_policy is set and not empty, it will be used as a pull policy for each bundled image.
Image example#
images:
repository: "my.own.repo"
konnectivity:
image: calico/kube-controllers
version: v3.16.2
metricsserver:
image: registry.k8s.io/metrics-server/metrics-server
version: v0.6.4
In the runtime the image names are calculated as my.own.repo/calico/kube-controllers:v3.16.2 and my.own.repo/metrics-server/metrics-server:v0.6.4. This only affects the the imgages pull location, and thus omitting an image specification here will not disable component deployment.
spec.extensions.helm#
spec.extensions.helm is the config file key in which you configure the list of Helm repositories and charts to deploy during cluster bootstrap (for more information, refer to Helm Charts).
spec.extensions.storage#
spec.extensions.storage controls bundled storage provider.
The default value external makes no storage deployed.
To enable embedded host-local storage provider use the following configuration:
spec:
extensions:
storage:
type: openebs_local_storage
spec.konnectivity#
The spec.konnectivity key is the config file key in which you configure Konnectivity-related settings.
agentPortagent port to listen on (default 8132)adminPortadmin port to listen on (default 8133)
spec.telemetry#
To improve the end-user experience k0s is configured by defaul to collect telemetry data from clusters and send it to the k0s development team. To disable the telemetry function, change the enabled setting to false.
The telemetry interval is ten minutes.
spec:
telemetry:
enabled: true
Disabling controller components#
k0s allows to completely disable some of the system components. This allows users to build a minimal Kubernetes control plane and use what ever components they need to fulfill their need for the control plane. Disabling the system components happens through a command line flag for the controller process:
--disable-components strings disable components (valid items: applier-manager,autopilot,control-api,coredns,csr-approver,endpoint-reconciler,helm,konnectivity-server,kube-controller-manager,kube-proxy,kube-scheduler,metrics-server,network-provider,node-role,system-rbac,worker-config)
Note: As of k0s 1.26, the kubelet-config component has been replaced by the worker-config component. k0s will issue a warning when the old component name is being used. It is scheduled for removal in k0s 1.27. Please update to the new component name.
If you use k0sctl, just add the flag when installing the cluster for the first
controller at spec.hosts.installFlags in the config file like e.g.:
spec:
hosts:
- role: controller
installFlags:
- --disable-components=metrics-server
As seen from the component list, the only always-on component is the Kubernetes api-server, without that k0s serves no purpose.