Book Image

The Kubernetes Book

By : Nigel Poulton, Pushkar Joglekar
Book Image

The Kubernetes Book

By: Nigel Poulton, Pushkar Joglekar

Overview of this book

Kubernetes is the leading orchestrator of cloud-native apps. With knowledge of how to work with Kubernetes, you can easily deploy and manage applications on the cloud or in your on-premises data center. The book begins by introducing you to Kubernetes and showing you how to install it. You’ll learn how to use Kubernetes Services and bring stable and reliable networking to apps that are deployed on Kubernetes. You'll delve deep into the powerful storage subsystem of Kubernetes and learn how to leverage the variety of external storage backends in your applications. As the book progresses, it shows you how to use features such as DaemonSets, Helm, and RBAC to enhance your Kubernetes applications. You'll explore the six categories of identifying vulnerabilities and look at a few ways to prevent and mitigate them. You'll also look at ways to secure the software delivery pipeline by discussing some image-related best practices. The book ends by sharing with you some resources that’ll help take your Kubernetes knowledge to the next level. By the end of the book, you’ll have the confidence and skills to leverage all the features of Kubernetes to develop scalable applications.
Table of Contents (23 chapters)
Free Chapter
1
Chapter 1
3
Chapter 2
5
Chapter 3
7
Chapter 4
9
Chapter 5
11
Chapter 6
13
Chapter 7
15
Chapter 8
17
Chapter 9
19
Chapter 10
21
Chapter 11

Deployment Theory

At a high level, we start with application code. That gets packaged as a container and wrapped in a Pod so it can run on Kubernetes. However, Pods don't self-heal, they don't scale, and they don't allow for easy updates or rollbacks. Deployments do all of these. As a result, we almost always run Pods via Deployments.

Figure 5.1 shows some Pods being managed by a Deployment.

Figure 5.1: Pods being managed by a deployment
Figure 5.1: Pods being managed by a deployment

It's important to know that a single Deployment can only manage a single type of Pod. For example, if you have an application with a Pod for the web frontend and another Pod for the catalog service, you'll need two Deployments. However, as we saw in Figure 5.1, a Deployment can manage multiple replicas of the same Pod. For example, Figure 5.1 could be a deployment that currently manages two replicated web server Pods.

The next thing to know is that Deployments are fully fledged objects in...