Chapter 3: Kubernetes

Introduction

In this chapter, we will explain what Kubernetes is, its features, and the reasons why you should use it. We will explore the evolution of Kubernetes from Borg, which is a cluster manager created by Google. We will also talk about the Cloud Native Computing Foundation (CNCF), which currently hosts the Kubernetes project, along with other cloud-native projects, like Prometheus, Fluentd, rkt, containerd, etc.

What is Kubernetes?

• Kubernetes is an open-source system for automating deployment, scaling, and management of containerized applications.

Why use K8s?

• Deployable in nearly every environment (eventually hybrid/multi-cloud). Portable, extensible, modular, pluggable.

What are the features of K8s?

• Automatic bin packing

  • Kubernetes automatically schedules containers based on resource needs and constraints, to maximize utilization without sacrificing availability.

• Self-healing

  • Kubernetes automatically replaces and reschedules containers from failed nodes. It kills and restarts containers unresponsive to health checks, based on existing rules/policy. It also prevents traffic from being routed to unresponsive containers.

• Horizontal scaling

  • With Kubernetes applications are scaled manually or automatically based on CPU or custom metrics utilization.

• Service discovery and Load balancing

  • Containers receive their own IP addresses from Kubernetes, white it assigns a single Domain Name System (DNS) name to a set of containers to aid in load-balancing requests across the containers of the set.

• Automated rollouts and rollbacks

  • Kubernetes seamlessly rolls out and rolls back application updates and configuration changes, constantly monitoring the application's health to prevent any downtime.

• Secret and configuration management

  • Kubernetes manages secrets and configuration details for an application separately from the container image, in order to avoid a re-build of the respective image. Secrets consist of confidential information passed to the application without revealing the sensitive content to the stack configuration, like on GitHub.

• Storage orchestration

  • Kubernetes automatically mounts software-defined storage (SDS) solutions to containers from local storage, external cloud providers, or network storage systems.

• Batch execution

  • Kubernetes supports batch execution, long-running jobs, and replaces failed containers.

K8s evolved from Borg. What features can be traced to Borg?

• API servers

• Pods

• IP-per-Pod

• Services

• Labels

What does the Cloud Native Computing Foundation (CNCF) do?

• The Cloud Native Computing Foundation (CNCF) is one of the projects hosted by the Linux Foundation. CNCF aims to accelerate the adoption of containers, microservices, and cloud-native applications.