I'm facing this kubelet error on my k8s cluster running CentOS 7. This error surfaced after I reboot the cluster nodes recently. I have not faced similar issue previously I reboot the machines.
I tried running swapoff -a to disable swap but it does not fix the problem.
Here's the systemctl status kubelet -l log:
[root@test-master ~]# systemctl status kubelet -l
● kubelet.service - kubelet: The Kubernetes Node Agent
Loaded: loaded (/usr/lib/systemd/system/kubelet.service; enabled; vendor preset: disabled)
Drop-In: /usr/lib/systemd/system/kubelet.service.d
└─10-kubeadm.conf
Active: activating (auto-restart) (Result: exit-code) since Mon 2022-05-30 13:59:51 +08; 822ms ago
Docs: https://kubernetes.io/docs/
Process: 9325 ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS (code=exited, status=1/FAILURE)
Main PID: 9325 (code=exited, status=1/FAILURE)
May 30 13:59:51 test-master kubelet[9325]: Insecure values: TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256, TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256, TLS_ECDHE_RSA_WITH_RC4_128_SHA, TLS_RSA_WITH_3DES_EDE_CBC_SHA, TLS_RSA_WITH_AES_128_CBC_SHA256, TLS_RSA_WITH_RC4_128_SHA. (DEPRECATED: This parameter should be set via the config file specified by the Kubelet's --config flag. See https://kubernetes.io/docs/tasks/administer-cluster/kubelet-config-file/ for more information.)
May 30 13:59:51 test-master kubelet[9325]: --tls-min-version string Minimum TLS version supported. Possible values: VersionTLS10, VersionTLS11, VersionTLS12, VersionTLS13 (DEPRECATED: This parameter should be set via the config file specified by the Kubelet's --config flag. See https://kubernetes.io/docs/tasks/administer-cluster/kubelet-config-file/ for more information.)
May 30 13:59:51 test-master kubelet[9325]: --tls-private-key-file string File containing x509 private key matching --tls-cert-file. (DEPRECATED: This parameter should be set via the config file specified by the Kubelet's --config flag. See https://kubernetes.io/docs/tasks/administer-cluster/kubelet-config-file/ for more information.)
May 30 13:59:51 test-master kubelet[9325]: --topology-manager-policy string Topology Manager policy to use. Possible values: 'none', 'best-effort', 'restricted', 'single-numa-node'. (default "none") (DEPRECATED: This parameter should be set via the config file specified by the Kubelet's --config flag. See https://kubernetes.io/docs/tasks/administer-cluster/kubelet-config-file/ for more information.)
May 30 13:59:51 test-master kubelet[9325]: --topology-manager-scope string Scope to which topology hints applied. Topology Manager collects hints from Hint Providers and applies them to defined scope to ensure the pod admission. Possible values: 'container', 'pod'. (default "container") (DEPRECATED: This parameter should be set via the config file specified by the Kubelet's --config flag. See https://kubernetes.io/docs/tasks/administer-cluster/kubelet-config-file/ for more information.)
May 30 13:59:51 test-master kubelet[9325]: -v, --v Level number for the log level verbosity
May 30 13:59:51 test-master kubelet[9325]: --version version[=true] Print version information and quit
May 30 13:59:51 test-master kubelet[9325]: --vmodule pattern=N,... comma-separated list of pattern=N settings for file-filtered logging (only works for text log format)
May 30 13:59:51 test-master kubelet[9325]: --volume-plugin-dir string The full path of the directory in which to search for additional third party volume plugins (default "/usr/libexec/kubernetes/kubelet-plugins/volume/exec/") (DEPRECATED: This parameter should be set via the config file specified by the Kubelet's --config flag. See https://kubernetes.io/docs/tasks/administer-cluster/kubelet-config-file/ for more information.)
May 30 13:59:51 test-master kubelet[9325]: --volume-stats-agg-period duration Specifies interval for kubelet to calculate and cache the volume disk usage for all pods and volumes. To disable volume calculations, set to a negative number. (default 1m0s) (DEPRECATED: This parameter should be set via the config file specified by the Kubelet's --config flag. See https://kubernetes.io/docs/tasks/administer-cluster/kubelet-config-file/ for more information.)
This is the content of /usr/lib/systemd/system/kubelet.service.d/10-kubeadm.conf mentioned in previous log:
[root@test-master ~]# cat /usr/lib/systemd/system/kubelet.service.d/10-kubeadm.conf
# Note: This dropin only works with kubeadm and kubelet v1.11+
[Service]
Environment="KUBELET_KUBECONFIG_ARGS=--bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf"
Environment="KUBELET_CONFIG_ARGS=--config=/var/lib/kubelet/config.yaml"
# This is a file that "kubeadm init" and "kubeadm join" generates at runtime, populating the KUBELET_KUBEADM_ARGS variable dynamically
EnvironmentFile=-/var/lib/kubelet/kubeadm-flags.env
# This is a file that the user can use for overrides of the kubelet args as a last resort. Preferably, the user should use
# the .NodeRegistration.KubeletExtraArgs object in the configuration files instead. KUBELET_EXTRA_ARGS should be sourced from this file.
EnvironmentFile=-/etc/sysconfig/kubelet
ExecStart=
ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS
I've also tried adding Environment="KUBELET_SYSTEM_PODS_ARGS=--pod-manifest-path=/etc/kubernetes/manifests --allow-privileged=true --fail-swap-on=false" to the file mentioned here along with systemctl daemon-reload and systemctl restart kubelet but it doesn't help.
Unfortunately, I'm not exactly sure about the server's version but it should be the same as my client version [v1.23.3].
[root@test-master ~]# kubectl version
Client Version: version.Info{Major:"1", Minor:"23", GitVersion:"v1.23.3", GitCommit:"816c97ab8cff8a1c72eccca1026f7820e93e0d25", GitTreeState:"clean", BuildDate:"2022-01-25T21:25:17Z", GoVersion:"go1.17.6", Compiler:"gc", Platform:"linux/amd64"}
The connection to the server 10.17.98.171:6443 was refused - did you specify the right host or port?
Is there anyway I can salvage my cluster without having to reset the entire cluster? I'm hoping I can access my deployments previously running in the cluster.
Update:
I tried to find the error messages in the log using journalctl -fu kubelet and this is the closest thing I can find.
May 31 08:58:12 test-master systemd[1]: kubelet.service holdoff time over, scheduling restart.
May 31 08:58:12 test-master systemd[1]: Stopped kubelet: The Kubernetes Node Agent.
May 31 08:58:12 test-master systemd[1]: Started kubelet: The Kubernetes Node Agent.
May 31 08:58:12 test-master kubelet[5280]: Error: failed to parse kubelet flag: unknown flag: --network-plugin
Also, here's my kubelet's version Kubernetes v1.24.1.
Seems like it's related to this issue on GitHub, https://github.com/kubernetes/website/issues/33640.
