Connectivity TLS Introduction

Securing communication in a Kubernetes cluster hinges on a solid understanding of TLS certificates and Certificate Authorities (CAs). Without this foundation, configuring and troubleshooting TLS-related issues can be challenging.

In a recent poll, many participants indicated limited experience with TLS certificates. To address this gap, this lesson series covers both general TLS fundamentals and Kubernetes-specific implementations.

Note

This section starts with the basics of public key cryptography and certificate lifecycles. If you’re already familiar with these topics, you can skip ahead to the Kubernetes-Specific Topics further below.

Goals for TLS Certificate Mastery

The image is a slide titled "Goals!" listing objectives related to TLS certificates, including understanding, generating, configuring, viewing, and troubleshooting them in the context of Kubernetes.

By the end of this module, you will be able to:

Objective	Description
Understand TLS certs and CAs	Explain public/private key pairs, trust chains, and the role of CAs
Generate and configure TLS certificates	Use tools such as `openssl`, `cfssl`, and Kubernetes resources
Inspect certificate contents and validity	Leverage `openssl x509`, `kubectl get csr`, and certificate metadata
Troubleshoot certificate issues	Diagnose common TLS handshake failures and misconfigurations in Kubernetes

Prerequisites: Core TLS Concepts

The image is an orange slide with the text "TLS Certificates (Pre-Req)" and an icon of a certificate.

Before diving into Kubernetes integrations, make sure you understand:

Public Key Cryptography: Asymmetric key pairs, digital signatures, and encryption.
Certificate Authorities (CAs): Root vs. intermediate CAs, trust stores, and signing processes.
Certificate Lifecycle: Creation (CSR), issuance, renewal, and revocation.

Warning

Ensure that openssl (version 1.1 or higher) is installed on your system. Certificate operations in this course rely on OpenSSL commands.

Kubernetes-Specific Topics

Once you’ve reviewed the TLS fundamentals above, the following Kubernetes-focused lectures will explore:

API Server and kubelet certificates – How Kubernetes generates and rotates its own certs.
Mutual TLS (mTLS) – Implementing service-to-service authentication within a cluster.
Cert-Manager integration – Automating certificate issuance and renewal.
Troubleshooting TLS in real clusters – Common errors, log analysis, and remediation steps.

References and Further Reading

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