Kubernetes

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. ...

What is a Helm Subchart and How to Use It When you start using Helm to manage applications in Kubernetes, you’ll quickly discover that not everything should live in a single chart. Sometimes, an application depends on other components — like a database, cache, or monitoring tool. This is where subcharts come into play. What is a Subchart? A subchart is simply another Helm chart that lives inside the charts/ directory of your main chart. It’s a way to define dependencies. For example, your app may need Redis. Instead of reinventing the wheel, you include the Redis Helm chart as a subchart. ...

Optimizing etcd on Slow Disks in Kubernetes In Kubernetes, etcd is the central database that stores the entire cluster state. If etcd runs on slow disks, you might notice performance issues: API requests slow down, pods take longer to schedule, and sometimes the cluster feels “laggy.” Why etcd Struggles on Slow Disks etcd is very I/O-intensive. Each write goes to disk to guarantee consistency. On spinning HDDs or cheap cloud disks with poor IOPS, etcd can quickly become a bottleneck. ...

What is a CronJob in Kubernetes? If you’ve ever used Linux, you probably know cron – a tool to schedule recurring tasks. Kubernetes has a similar concept called CronJob. A CronJob in Kubernetes is a resource that allows you to run jobs on a schedule, like database backups, sending reports, or periodic cleanup tasks. How CronJobs Work A Job in Kubernetes runs a task once and then exits. A CronJob is a Job with a schedule, defined in cron format (* * * * *). Every time the schedule is triggered, Kubernetes creates a new Job pod. ...

What is MetalLB? If you run Kubernetes in a cloud (AWS, GCP, Azure), creating a LoadBalancer service gives you an external IP automatically. But what if your cluster is bare metal — your own servers, without cloud integration? That’s where MetalLB comes in. MetalLB is a load balancer implementation for bare-metal Kubernetes clusters. It allows you to expose services of type LoadBalancer without relying on cloud providers. How MetalLB Works MetalLB assigns external IPs to services in one of two modes: ...