Book Image

The Kubernetes Workshop

By : Zachary Arnold, Sahil Dua, Wei Huang, Faisal Masood, Mélony Qin, Mohammed Abu Taleb
Book Image

The Kubernetes Workshop

By: Zachary Arnold, Sahil Dua, Wei Huang, Faisal Masood, Mélony Qin, Mohammed Abu Taleb

Overview of this book

Thanks to its extensive support for managing hundreds of containers that run cloud-native applications, Kubernetes is the most popular open source container orchestration platform that makes cluster management easy. This workshop adopts a practical approach to get you acquainted with the Kubernetes environment and its applications. Starting with an introduction to the fundamentals of Kubernetes, you’ll install and set up your Kubernetes environment. You’ll understand how to write YAML files and deploy your first simple web application container using Pod. You’ll then assign human-friendly names to Pods, explore various Kubernetes entities and functions, and discover when to use them. As you work through the chapters, this Kubernetes book will show you how you can make full-scale use of Kubernetes by applying a variety of techniques for designing components and deploying clusters. You’ll also get to grips with security policies for limiting access to certain functions inside the cluster. Toward the end of the book, you’ll get a rundown of Kubernetes advanced features for building your own controller and upgrading to a Kubernetes cluster without downtime. By the end of this workshop, you’ll be able to manage containers and run cloud-based applications efficiently using Kubernetes.
Table of Contents (20 chapters)

The Pod Scheduling Process

The scheduler works in a three-step process: filtering, scoring, and assigning. Let's take a look at what happens during the execution of each of these steps. An overview of the process is described in the following diagram:

Figure 17.1: An overview of how the Kubernetes Scheduler selects a suitable node


Filtering is a process in which the Kubernetes Scheduler runs a series of checks or filters to see which nodes are not suitable to run the target Pod. An example of a filter is to see if the node has enough CPU and memory to host the Pod, or if the storage volume requested by the Pod can be mounted on the host. If the cluster has no node that's suitable to meet the requirements of the Pod, then the Pod is deemed un-schedulable and is not executed on the cluster.


Once the Kubernetes Scheduler has a list of feasible nodes, the second step is to score the nodes and find the best node(s) to host the...