Book Image

The DevOps 2.3 Toolkit

By : Viktor Farcic
Book Image

The DevOps 2.3 Toolkit

By: Viktor Farcic

Overview of this book

Building on The DevOps 2.0 Toolkit, The DevOps 2.1 Toolkit: Docker Swarm, and The DevOps 2.2 Toolkit: Self-Sufficient Docker Clusters, Viktor Farcic brings his latest exploration of the DevOps Toolkit as he takes you on a journey to explore the features of Kubernetes. The DevOps 2.3 Toolkit: Kubernetes is a book in the series that helps you build a full DevOps Toolkit. This book in the series looks at Kubernetes, the tool designed to, among other roles, make it easier in the creation and deployment of highly available and fault-tolerant applications at scale, with zero downtime. Within this book, Viktor will cover a wide range of emerging topics, including what exactly Kubernetes is, how to use both first and third-party add-ons for projects, and how to get the skills to be able to call yourself a “Kubernetes ninja.” Work with Viktor and dive into the creation and exploration of Kubernetes with a series of hands-on guides.
Table of Contents (18 chapters)
The End
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Scaling Pods With ReplicaSets

Most applications should be scalable and all must be fault tolerant. Pods do not provide those features, ReplicaSets do.

We learned that Pods are the smallest unit in Kubernetes. We also learned that Pods are not fault tolerant. If a Pod is destroyed, Kubernetes will do nothing to remedy the problem. That is, if Pods are created without Controllers.

The first Controller we'll explore is called ReplicaSet. Its primary, and pretty much only function, is to ensure that a specified number of replicas of a Pod matches the actual state (almost) all the time. That means that ReplicaSets make Pods scalable.

We can think of ReplicaSets as a self-healing mechanism. As long as elementary conditions are met (for example, enough memory and CPU), Pods associated with a ReplicaSet are guaranteed to run. They provide fault-tolerance and high availability.