Changing the IP addresses of Kubernetes nodes is rarely a good idea — it can lead to broken networking, node unavailability, or even complete cluster failure. This article explains why you should avoid it, and provides a step-by-step recovery plan if you must do it. 1. Why Node IPs Matter Kubernetes heavily relies on the IP addresses of nodes for: Scheduling and node identity kubelet and API server communication CNI and network overlays DNS and service discovery TLS certificates tied to node IPs Changing an IP breaks all these associations — kubelet may fail to register, Pods may not communicate, and the control plane may mark the node as NotReady. ...

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. ...

DDoS (Distributed Denial of Service) attacks are among the most common threats to cloud-native infrastructure and APIs. They can flood your services with traffic, exhausting resources and causing downtime. In this article, we’ll explore effective strategies to prevent and mitigate DDoS attacks — from rate limiting to cloud-based protections. 1. What Is a DDoS Attack? A DDoS attack occurs when a network of compromised machines sends overwhelming traffic to a target server or service, aiming to exhaust bandwidth or system resources. ...

Java Frameworks Overview: Choosing the Right Tool for Your Project Java remains one of the most popular programming languages, especially for backend development. In this article, we’ll take a look at the leading Java frameworks and help you decide which one fits your needs. Why Use a Java Framework? Frameworks simplify development by offering: Predefined structure and best practices Boilerplate reduction Support for dependency injection, configuration, and testing 1. Spring Boot Use case: Enterprise apps, microservices ...

Long-running queries can cause serious performance issues in PostgreSQL. Here’s how to automate their termination to keep your DB healthy. Why Kill Long-Running Queries? In real-world scenarios, long-running queries often: Lock tables or rows Exhaust memory or CPU Cause deadlocks Block migrations or monitoring tools Typical causes: Forgotten WHERE clauses Heavy reporting queries Hung jobs or broken clients How It Works We’ll use a Bash script to: Connect to PostgreSQL Detect queries older than 60 seconds Automatically terminate them Bash Script to Kill Long Queries 1. Define connection and timeout #!/bin/bash PG_CONN="postgres://user:pass@postgres-host/postgres-db" QUERY_TIMEOUT="60" PSQL_RUN="psql $PG_CONN -Atc" 2. Build the query QUERY="SELECT pid FROM pg_stat_activity WHERE now() - query_start > '${QUERY_TIMEOUT} seconds'::interval" 3. Run and kill echo "Checking for queries longer than $QUERY_TIMEOUT seconds..." pids=$(${PSQL_RUN} "$QUERY") for pid in $pids; do echo "Terminating PID $pid..." ${PSQL_RUN} "SELECT pg_terminate_backend($pid)" done Automate with Cron To run every 5 minutes: ...