Troubleshooting kubectl

This documentation is about investigating and diagnosing kubectl related issues. If you encounter issues accessing kubectl or connecting to your cluster, this document outlines various common scenarios and potential solutions to help identify and address the likely cause.

Before you begin

• You need to have a Kubernetes cluster.
• You also need to have kubectl installed - see install tools

Verify kubectl setup

Make sure you have installed and configured kubectl correctly on your local machine. Check the kubectl version to ensure it is up-to-date and compatible with your cluster.

Check kubectl version:

kubectl version

You'll see a similar output:

Client Version: version.Info{Major:"1", Minor:"27", GitVersion:"v1.27.4",GitCommit:"fa3d7990104d7c1f16943a67f11b154b71f6a132", GitTreeState:"clean",BuildDate:"2023-07-19T12:20:54Z", GoVersion:"go1.20.6", Compiler:"gc", Platform:"linux/amd64"}
Kustomize Version: v5.0.1
Server Version: version.Info{Major:"1", Minor:"27", GitVersion:"v1.27.3",GitCommit:"25b4e43193bcda6c7328a6d147b1fb73a33f1598", GitTreeState:"clean",BuildDate:"2023-06-14T09:47:40Z", GoVersion:"go1.20.5", Compiler:"gc", Platform:"linux/amd64"}

If you see Unable to connect to the server: dial tcp <server-ip>:8443: i/o timeout, instead of Server Version, you need to troubleshoot kubectl connectivity with your cluster.

Make sure you have installed the kubectl by following the official documentation for installing kubectl, and you have properly configured the $PATH environment variable.

Check kubeconfig

The kubectl requires a kubeconfig file to connect to a Kubernetes cluster. The kubeconfig file is usually located under the ~/.kube/config directory. Make sure that you have a valid kubeconfig file. If you don't have a kubeconfig file, you can obtain it from your Kubernetes administrator, or you can copy it from your Kubernetes control plane's /etc/kubernetes/admin.conf directory. If you have deployed your Kubernetes cluster on a cloud platform and lost your kubeconfig file, you can re-generate it using your cloud provider's tools. Refer the cloud provider's documentation for re-generating a kubeconfig file.

Check if the $KUBECONFIG environment variable is configured correctly. You can set $KUBECONFIGenvironment variable or use the --kubeconfig parameter with the kubectl to specify the directory of a kubeconfig file.

Check VPN connectivity

If you are using a Virtual Private Network (VPN) to access your Kubernetes cluster, make sure that your VPN connection is active and stable. Sometimes, VPN disconnections can lead to connection issues with the cluster. Reconnect to the VPN and try accessing the cluster again.

Authentication and authorization

If you are using the token based authentication and the kubectl is returning an error regarding the authentication token or authentication server address, validate the Kubernetes authentication token and the authentication server address are configured properly.

If kubectl is returning an error regarding the authorization, make sure that you are using the valid user credentials. And you have the permission to access the resource that you have requested.

Verify contexts

Kubernetes supports multiple clusters and contexts. Ensure that you are using the correct context to interact with your cluster.

List available contexts:

kubectl config get-contexts

Switch to the appropriate context:

kubectl config use-context <context-name>

API server and load balancer

The kube-apiserver server is the central component of a Kubernetes cluster. If the API server or the load balancer that runs in front of your API servers is not reachable or not responding, you won't be able to interact with the cluster.

Check the if the API server's host is reachable by using ping command. Check cluster's network connectivity and firewall. If your are using a cloud provider for deploying the cluster, check your cloud provider's health check status for the cluster's API server.

Verify the status of the load balancer (if used) to ensure it is healthy and forwarding traffic to the API server.

TLS problems

The Kubernetes API server only serves HTTPS requests by default. In that case TLS problems may occur due to various reasons, such as certificate expiry or chain of trust validity.

You can find the TLS certificate in the kubeconfig file, located in the ~/.kube/config directory. The certificate-authority attribute contains the CA certificate and the client-certificate attribute contains the client certificate.

Verify the expiry of these certificates:

openssl x509 -noout -dates -in $(kubectl config view --minify --output 'jsonpath={.clusters[0].cluster.certificate-authority}')

output:

notBefore=Sep  2 08:34:12 2023 GMT
notAfter=Aug 31 08:34:12 2033 GMT

openssl x509 -noout -dates -in $(kubectl config view --minify --output 'jsonpath={.users[0].user.client-certificate}')

output:

notBefore=Sep  2 08:34:12 2023 GMT
notAfter=Sep  2 08:34:12 2026 GMT

Verify kubectl helpers

Some kubectl authentication helpers provide easy access to Kubernetes clusters. If you have used such helpers and are facing connectivity issues, ensure that the necessary configurations are still present.

Check kubectl configuration for authentication details:

kubectl config view

If you previously used a helper tool (for example, kubectl-oidc-login), ensure that it is still installed and configured correctly.