CKA HANDS-ON LABS

This document outlines Kubernetes probes and configuration management through practical labs. Lab 1 addresses the CrashLoopBackOff issue for slow applications by introducing startup probes to prevent liveness probes from interfering during initialization. Lab 2 demonstrates how readiness probes control traffic flow, ensuring unhealthy pods are temporarily removed from service without restarting. Lab 3 focuses on liveness probes, explaining their role in automatically restarting unresponsive containers. Lab 4 highlights that environment variables injected from ConfigMaps are immutable and require a deployment restart to apply changes. Lab 5 clarifies that while mounted ConfigMap files are updated, the application must manually reload its configuration to reflect the changes. Lab 6 warns about the security risks of injecting secrets as environment variables, as they are visible in plain text after base64 encoding. The document emphasizes the importance of understanding the distinct functions of startup, readiness, and liveness probes. It also stresses the need for manual restarts for ConfigMap-based environment variable updates. Finally, it advises caution with secrets due to their plain text visibility and the necessity of robust RBAC. Debugging tools like `describe`, `logs`, and `exec` are crucial for troubleshooting.