Book Image

Mastering Kubernetes

By : Gigi Sayfan
Book Image

Mastering Kubernetes

By: Gigi Sayfan

Overview of this book

Kubernetes is an open source system to automate the deployment, scaling, and management of containerized applications. If you are running more than just a few containers or want automated management of your containers, you need Kubernetes. This book mainly focuses on the advanced management of Kubernetes clusters. It covers problems that arise when you start using container orchestration in production. We start by giving you an overview of the guiding principles in Kubernetes design and show you the best practises in the fields of security, high availability, and cluster federation. You will discover how to run complex stateful microservices on Kubernetes including advanced features as horizontal pod autoscaling, rolling updates, resource quotas, and persistent storage back ends. Using real-world use cases, we explain the options for network configuration and provides guidelines on how to set up, operate, and troubleshoot various Kubernetes networking plugins. Finally, we cover custom resource development and utilization in automation and maintenance workflows. By the end of this book, you’ll know everything you need to know to go from intermediate to advanced level.
Table of Contents (22 chapters)
Mastering Kubernetes
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
Index

Handling scarce resources with limits and quotas


With the horizontal pod autoscaler creating pods on the fly, we need to think about managing our resources. Scheduling can easily get out of control, and inefficient use of resources is a real concern. There are several factors that can interact with each other in subtle ways:

  • Overall cluster capacity

  • Resource granularity per node

  • Division of workloads per namespace

  • Daemon sets

  • Stateful sets

First, let's understand the core issue. The Kubernetes scheduler has to take into account all these factors when it schedules pods. If there are conflicts or a lot of overlapping requirements, then Kubernetes may have a problem finding room to schedule new pods. For example, a very extreme yet simple scenario is that a DaemonSet runs on every node a pod that requires 50% of the available memory. Now, Kubernetes can't schedule any pod that needs more than 50% memory because the DaemonSet pod gets priority. Even if you provision new nodes, the DaemonSet will immediately...