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This brief—but important—lesson introduces Zero Trust Architecture in the context of Istio and covers authentication and authorization for workloads. We’ll start by clarifying what Zero Trust means for workloads and how Istio’s PeerAuthentication resource is used to implement it. Then we’ll examine how encrypted traffic is handled and how authentication and encryption interact.
The image lists four objectives related to Istio: introducing Zero-Trust Architecture, exploring authentication resources, explaining encrypted traffic handling, and discussing authorization after authentication.
After authentication, the natural follow-up is: what can an authenticated identity do? Istio’s AuthorizationPolicy answers that by letting you define fine-grained allow/deny rules for workloads. We’ll explain common policy patterns, the kinds of rules you can write, and the complexity that arises when multiple policies interact. You should expect three core questions around authentication and authorization; mastering these will be important for understanding how Istio secures traffic between workloads. Finally, we’ll discuss how Istio’s ambient mode interacts with security resources. Ambient mode material is useful to understand modern Istio deployments, although it is not required for the exam objectives.
This lesson focuses on concepts and configurations for Istio authentication and authorization. Ambient mode details are included for completeness but are not required for the exam.
What you’ll learn in this lesson:
  • Why Zero Trust matters for workloads and how Istio implements it.
  • How PeerAuthentication and mTLS control workload authentication and encryption.
  • How AuthorizationPolicy enforces what authenticated identities are allowed to do.
  • How authentication and authorization interact, and patterns to avoid policy conflicts.
  • A brief overview of Istio Ambient mode and its relationship with these resources.
Quick reference table of core resources: Expect to answer these three core questions by the end of this lesson:
  1. How does Istio establish and enforce workload identity and mutual TLS (mTLS)?
  2. How does encrypted traffic (mTLS) affect authentication configuration and policy decisions?
  3. Once a request is authenticated, how do you express and scope authorization rules with AuthorizationPolicy?
If you’re ready, grab a cup of coffee and let’s begin the lesson.

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