Kubernetes Lecture Notes

Introduction to Kubernetes

• Kubernetes is an open-source container orchestration platform.
• It automates deployment, scaling, and management of containerized applications.
• Originated from Google's internal system, Borg.
• Open-sourced by Google in 2014 as Kubernetes.

Why is it called k8s?

• "k8s" is an abbreviation where "8" represents the 8 letters between "k" and "s" in "Kubernetes".
• Similar abbreviations: i18n (internationalization), l10n (localization).

Kubernetes Cluster

• Cluster consists of machines (nodes) running containerized applications.
• Core components:
  • Control Plane
    • Manages cluster state.
    • Typically runs on multiple nodes across data centers.
  • Worker Nodes
    • Run containerized application workloads.

Control Plane Components

• API Server: Primary interface, exposes RESTful API.
• etcd: Distributed key-value store for persistent state.
• Scheduler: Schedules pods onto worker nodes based on resources.
• Controller Manager: Runs controllers managing the cluster state (e.g., replication, deployment controllers).

Worker Nodes Components

• kubelet: Daemon on each node, communicates with control plane to manage pods.
• Container Runtime: Pulls images, starts/stops containers, manages resources.
• kube-proxy: Network proxy for routing traffic, providing load balancing.

Why Use Kubernetes?

Benefits

• Scalability & Availability: Features include self-healing, rollbacks, horizontal scaling.
• Portability: Consistent management across on-premise, public cloud, or hybrid environments.

Drawbacks

• Complexity: Difficult to set up and manage, especially for newcomers.
• Cost: Requires significant resources, may be overkill for small organizations.

Managed Kubernetes Services

• Solution for Complexity & Cost: Use managed services from cloud providers.
• Popular services: Amazon EKS, Google Cloud GKE, Azure AKS.
• Benefits: Offloads control plane management, ideal for mid-sized organizations.

Conclusion

• Recommendation for Small Organizations: YAGNI (You Ain’t Gonna Need It).
• Further Learning: Books and newsletters available for deeper understanding of system design.

Additional Resources

• Subscribe to further learnings.
• Thank you message and invitation for next session.