Troubleshooting

kube-apiserver Not Starting: Troubleshooting Guide The kube-apiserver is the heart of any Kubernetes cluster. If it doesn’t start, the entire control plane is effectively down — meaning kubectl and controllers won’t work. Let’s go through common causes and fixes. Symptoms kubectl commands fail with connection errors. In kubectl get pods -n kube-system, the kube-apiserver pod is CrashLoopBackOff or not running. Logs may contain messages like etcd connection refused, failed to listen on port 6443, or certificate errors. Common Causes and Fixes 1. Port Conflicts The API server binds to 6443 by default. If another process is already listening there, kube-apiserver won’t start. ...

kube-scheduler Not Starting: Troubleshooting Guide The kube-scheduler is a critical control plane component in Kubernetes. If it doesn’t start, pods cannot be scheduled to nodes — leaving them stuck in a Pending state. Here’s how to troubleshoot when the scheduler refuses to start. Common Symptoms kubectl get pods -n kube-system shows kube-scheduler CrashLoopBackOff or not running at all. Pods stay in Pending forever. Logs contain errors like failed to bind to port or etcd connection refused. Possible Causes and Fixes 1. Port Conflicts By default, kube-scheduler listens on 10259 (secured) and optionally 10251 (insecure). If another process is already using the port, scheduler won’t start. ...

Introduction etcd is a distributed key-value store that plays a critical role in Kubernetes by storing cluster configuration and state. When etcd runs into problems, it can cause cluster instability or downtime. This article covers common etcd errors, their underlying causes, and actionable solutions. 1. etcdserver: request timed out ❓ Cause Occurs when etcd members can’t communicate efficiently, often due to network issues or disk I/O latency. 🛠️ Solution Check disk performance: iostat -xz 1 Ensure etcd data is on SSD storage. Check network latency and connectivity between cluster members: ping <etcd-member-IP> 2. etcdserver: leader changed ❓ Cause This is often seen when leadership changes too frequently, indicating instability in the etcd cluster. ...

Common Ingress Errors in Kubernetes Ingress is a powerful Kubernetes resource that manages external access to services within your cluster. However, it often becomes a source of confusion and frustration due to misconfigurations or overlooked details. This article outlines the most common Ingress errors and how to fix them. 1. Misconfigured Annotations Annotations can control features like URL rewrites, authentication, and rate limiting. Incorrect annotations may silently break your setup. ...

Understanding ndots in Kubernetes DNS Resolution The ndots option in DNS configuration plays a subtle but important role in how domain names are resolved inside Kubernetes pods. Incorrectly configured ndots can lead to unnecessary DNS queries, delays, or failed resolutions. What is ndots? ndots is a setting in /etc/resolv.conf that determines whether a DNS query is treated as a fully qualified domain name (FQDN) or a partial name requiring search path resolution. ...