Set Kubelet parameters via a config file
FEATURE STATE: Kubernetes v1.8 alpha
This feature is currently in a alpha state, meaning:
- The version names contain alpha (e.g. v1alpha1).
- Might be buggy. Enabling the feature may expose bugs. Disabled by default.
- Support for feature may be dropped at any time without notice.
- The API may change in incompatible ways in a later software release without notice.
- Recommended for use only in short-lived testing clusters, due to increased risk of bugs and lack of long-term support.
As of Kubernetes 1.8, a subset of the Kubelet’s configuration parameters may be set via an on-disk config file, as a substitute for command-line flags. In the future, most of the existing command-line flags will be deprecated in favor of providing parameters via a config file, which simplifies node deployment.
- Before you begin
- Create the config file
- Start a Kubelet process configured via the config file
- Relationship to Dynamic Kubelet Config
Before you begin
- A v1.8 or higher Kubelet binary must be installed.
Create the config file
The subset of the Kubelet’s configuration that can be configured via a file
is defined by the KubeletConfiguration struct
here (v1alpha1).
The configuration file must be a JSON or YAML representation of the parameters
in this struct. Note that this structure, and thus the config file API,
is still considered alpha and is not subject to stability gurarantees.
Create a file named kubelet in its own directory and make sure the directory
and file are both readable by the Kubelet. You should write your intended
Kubelet configuration in this kubelet file.
For a trick to generate a configuration file from a live node, see Reconfigure a Node’s Kubelet in a Live Cluster.
Start a Kubelet process configured via the config file
Start the Kubelet with the KubeletConfigFile feature gate enabled and the
Kubelet’s --init-config-dir flag set to the location of the directory
containing the kubelet file. The Kubelet will then load the parameters defined
by KubeletConfiguration from the kubelet file, rather than from their
associated command-line flags.
Relationship to Dynamic Kubelet Config
If you are using the Dynamic Kubelet Configuration
feature, the configuration provided via --init-config-dir will be considered
the “last known good” configuration by the automatic rollback mechanism.
Note that the layout of the files in the --init-config-dir mirrors the layout
of data in the ConfigMaps used for Dynamic Kubelet Config; the file names are
the same as the keys of the ConfigMap, and the file contents are JSON or YAML
representations of the same structures. Today, the only pair is
kubelet:KubeletConfiguration, though more may emerge in the future.
See Reconfigure a Node’s Kubelet in a Live Cluster
for more information.