Complete Kubernetes Course Notes

Course Overview

• Mix of theoretical explanations and hands-on demos.
• Topics covered:
  • Introduction to Kubernetes
  • Installation of Minikube for local clusters
  • Kubernetes command line tool: kubectl
  • YAML configuration files for Kubernetes
  • Deployment of applications in Kubernetes
  • Advanced concepts such as namespaces, Ingress, and Helm.

Introduction to Kubernetes

• Definition: Open-source container orchestration framework developed by Google.
• Purpose: Manages applications made up of many containers across various environments.
• Key Features:
  • High availability
  • Scalability
  • Disaster recovery

Core Concepts

1. Pods:

   • Basic unit of Kubernetes, represents a single instance of a running process in a cluster.
   • Can run multiple containers but typically hosts one main application container.

2. Services:

   • Expose applications running on a set of Pods as a network service.
   • Types of services: ClusterIP, NodePort, LoadBalancer, Headless.

3. Deployments:

   • A method for managing the deployment of Pods.
   • Allows scaling, updating, and maintaining Pods.

4. ConfigMaps and Secrets:

   • External configuration and sensitive data storage.
   • ConfigMaps store non-sensitive data, Secrets store sensitive data (e.g., passwords).

5. Volumes:

   • Used to persist data across Pod restarts.
   • Types include Persistent Volumes and Persistent Volume Claims.
   • Data can be stored in local or remote storage.

Advanced Concepts

• Namespaces: Logical partitions in a Kubernetes cluster to organize resources.
• Ingress: Manages external access to services in a cluster, providing HTTP routing.
• Helm: Package manager for Kubernetes; allows easy deployment of applications using charts.

Kubernetes Architecture

• Master Node: Controls the cluster, schedules Pods, and manages the cluster state.
• Worker Node: Hosts the Pods that run the applications.
• Components: Kubelet, Kube-proxy, API server, Scheduler, Controller Manager, etcd.

Services in Depth

1. ClusterIP: Default service type, only accessible from within the cluster.
2. NodePort: Exposes the service on each node's IP at a static port.
3. LoadBalancer: Creates an external load balancer in supported cloud providers.
4. Headless Services: Allows direct access to Pod IPs, useful for stateful applications.

Persistent Storage

• Persistent Volume (PV): Represents a piece of storage in the cluster.
• Persistent Volume Claim (PVC): User's request for storage.
• Storage Classes: Define different types of storage and provision them dynamically.

Stateful Sets

• Used for deploying stateful applications (e.g., databases).
• Each Pod has a unique identity and stable storage.
• Pods are created and deleted in a specific order to maintain consistency.

Conclusion

• Kubernetes provides powerful abstractions for managing containerized applications.
• Understanding the core components and their interactions is essential for effective Kubernetes usage.