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

What is OPA and how does it work?

OPA is a lightweight authorization engine that fits well in Kubernetes. It didn't get its start in Kubernetes, but it's certainly found a home there. There's no requirement to build dynamic admission controllers in OPA, but it's very good at it and there are extensive resources and existing policies that can be used to start your policy library.

This section provides a high-level overview of OPA and its components with the rest of the chapter getting into the details of an OPA implementation in Kubernetes.

OPA architecture

OPA comprises three components – the HTTP listener, the policy engine, and the database:

Figure 8.1: OPA architecture

The database used by OPA is in memory and ephemeral. It doesn't persist information used to make policy decisions. On the one hand, this makes OPA very scalable since it is essentially an authorization microservice. On the other hand, this means that every...