Book Image

Kubernetes – An Enterprise Guide - Second Edition

By : Marc Boorshtein, Scott Surovich
Book Image

Kubernetes – An Enterprise Guide - Second Edition

By: Marc Boorshtein, Scott Surovich

Overview of this book

Kubernetes has taken the world by storm, becoming the standard infrastructure for DevOps teams to develop, test, and run applications. With significant updates in each chapter, this revised edition will help you acquire the knowledge and tools required to integrate Kubernetes clusters in an enterprise environment. The book introduces you to Docker and Kubernetes fundamentals, including a review of basic Kubernetes objects. You’ll get to grips with containerization and understand its core functionalities such as creating ephemeral multinode clusters using KinD. The book has replaced PodSecurityPolicies (PSP) with OPA/Gatekeeper for PSP-like enforcement. You’ll integrate your container into a cloud platform and tools including MetalLB, externalDNS, OpenID connect (OIDC), Open Policy Agent (OPA), Falco, and Velero. After learning to deploy your core cluster, you’ll learn how to deploy Istio and how to deploy both monolithic applications and microservices into your service mesh. Finally, you will discover how to deploy an entire GitOps platform to Kubernetes using continuous integration and continuous delivery (CI/CD).
Table of Contents (17 chapters)
15
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16
Index

Using Rego to write policies

Rego is a language specifically designed for policy writing. It is different from most languages you have likely written code in. Typical authorization code will look something like the following:

//assume failure
boolean allowed = false;
//on certain conditions allow access
if (someCondition) {
  allowed = true;
}
//are we authorized?
if (allowed) {
  doSomething();
}

Authorization code will generally default to unauthorized, with a specific condition having to happen in order to allow the final action to be authorized. Rego takes a different approach. Rego is generally written to authorize everything unless a specific set of conditions happens.

Another major difference between Rego and more general programming languages is that there are no explicit if/then/else control statements. When a line of Rego is going to make a decision, the code is interpreted as "if this line is false, stop execution." For instance, the following code...