In Kubernetes, a Rolling Update is the default deployment strategy used to update applications without downtime. However, if the update includes a bad configuration—such as an incorrect environment variable, bad image, broken readiness probe, or wrong secret—it can partially or completely break your application. 1. What Is a Rolling Deployment? A Rolling Deployment in Kubernetes…

In Kubernetes, etcd is a distributed key-value store that acts as the brain of the cluster. It stores all cluster data—including node information, Pod definitions, ConfigMaps, Secrets, and more. If etcd fails, the entire Kubernetes control plane is affected. 1. What is etcd? etcd is a high-availability, strongly consistent, distributed key-value store built on the…

In Kubernetes, Pod readiness is crucial in determining whether a Pod should receive traffic from Services. Kubernetes uses readiness probes to decide if a Pod is ready to serve requests. But what if a Pod is unready and still receives traffic? 1. What Does “Unready” Mean? A Pod is marked “Ready” when: Readiness Probe Example:…

1. Introduction In Kubernetes, a Service is used to expose one or more Pods under a single IP address and DNS name. This is made possible through a selector, which connects the Service to the appropriate Pods by matching their labels. But what if the selector doesn’t match any pods? This situation is quite common…

1. Introduction In a Kubernetes cluster, a node is a worker machine (virtual or physical) that runs containerized workloads. Each node has finite resources—CPU, memory, disk, and network bandwidth. If a node runs out of memory, Kubernetes and the underlying OS (typically Linux) must respond immediately to prevent system crashes. 2. What is Memory Pressure?…

1. Introduction In Kubernetes, CoreDNS is a critical system component that provides DNS-based service discovery. All internal service-to-service communication relies on it. When CoreDNS fails, the DNS resolution within the cluster breaks, which can lead to cascading application failures. 2. What is CoreDNS? CoreDNS is a DNS server that runs as a Deployment in the…

1. What is CrashLoopBackOff? CrashLoopBackOff is a pod status in Kubernetes that indicates a container in the pod has crashed repeatedly and Kubernetes is backing off (delaying) before trying to restart it again. You might see this with: 2. Why Does a Pod Enter CrashLoopBackOff? It occurs when: Common Causes: 3. What Happens Internally in…

1. Create a Spring Boot Application Use Spring Initializr to generate a new Spring Boot project with the following dependencies: Create a new Spring Boot project and add a simple REST controller. 2. Update application.properties (Optional) You can set the server port in src/main/resources/application.properties: 3. Build the Application Run the following command to package the…

Helm charts are packages of pre-configured Kubernetes resources. They allow you to define, install, and upgrade even the most complex Kubernetes applications. This tutorial will guide you through the process of creating a basic Helm chart. Prerequisites: 1. Setting up the Chart Structure Use the helm create command to generate a basic chart structure: This…

Introduction In this tutorial, we will explore the helm template command and understand why it is useful in Helm-based Kubernetes deployments. The Helm team initially introduced the –dry-run option to help debug templates before installation or upgrade. However, teams started using these generated templates directly with kubectl, leading to unexpected issues. To address these concerns,…