Learning Helm: Managing Apps on Kubernetes

Description

This book introduces Helm, the package manager for Kubernetes. It explains how Helm fits in with the rest of the Kubernetes ecosystem, and details how the Helm client can be used to add, manage, and monitor applications running inside of Kubernetes. There are thousands of Helm charts (packages) available today, but chart development is easy. This guide walks through the process of creating charts to package simple applications, and then works through more advanced use cases. Written by creators of Helm, not only does this prove a valuable reference, but also a glimpse into the design and best practices of the most beloved package management system for Kubernetes. Copyright Table of Contents Preface Who Should Read This Book Why We Wrote This Book Navigating This Book Conventions Used in This Book Using Code Examples O’Reilly Online Learning How to Contact Us Acknowledgments Chapter 1. Introducing Helm The Cloud Native Ecosystem Containers and Microservices Schedules and Kubernetes Helm’s Goals From Zero to Kubernetes Package Management Security, Reusability, and Configurability Helm’s Architecture Kubernetes Resources Charts Resources, Installations, and Releases A Brief Note About Helm 2 Conclusion Chapter 2. Using Helm Installing and Configuring the Helm Client Installing a Prebuilt Binary Guidance on Building from Source Working with Kubernetes Clusters Getting Started with Helm Adding a Chart Repository Searching a Chart Repository Installing a Package Configuration at Installation Time Listing Your Installations Upgrading an Installation Configuration Values and Upgrades Uninstalling an Installation How Helm Stores Release Information Conclusion Chapter 3. Beyond the Basics with Helm Templating and Dry Runs The --dry-run Flag The helm template Command Learning About a Release Release Records Listing Releases Find Details of a Release with helm get History and Rollbacks Keeping History and Rolling Back A Deep Dive into Installs and Upgrades The --generate-name and --name-template Flags The --create-namespace Flag Using helm upgrade --install The --wait and --atomic Flags Upgrading with --force and --cleanup-on-fail Conclusion Chapter 4. Building a Chart The Chart Creation Command The Chart.yaml File Modifying Templates The Deployment Using the Values File Container Images Exposing Services Resource Limits Packaging the Chart Linting Charts Conclusion Chapter 5. Developing Templates The Template Syntax Actions Information Helm Passes to Templates Pipelines Template Functions Methods Querying Kubernetes Resources In Charts if/else/with Variables Loops Named Templates Structuring Your Templates for Maintainability Debugging Templates Dry Run Getting Installed Manifests Linting Charts Conclusion Chapter 6. Advanced Chart Features Chart Dependencies Conditional Flags for Enabling Dependencies Importing Values from Child to Parent Charts Library Charts Schematizing Values Files Hooks Adding Tests to Charts Helm Test Chart Testing Tool Security Considerations Custom Resource Definitions Conclusion Chapter 7. Chart Repositories The Repository Index An Example of a Chart Repository Index Generating an Index Adding to an Existing Index Setting Up a Chart Repository A Simple Chart Repository with Python Securing a Chart Repository Real-World Example: Using GitHub Pages Using Chart Repositories Adding a Repository Downloading Charts Listing Repositories Updating Repositories Removing a Repository Experimental OCI Support Enabling OCI Support Running a Local Registry Logging In to a Registry Logging Out of a Registry Storing a Chart in the Cache Listing Charts in the Cache Exporting a Chart from the Cache Pushing a Chart to the Registry Pulling a Chart from the Registry Removing a Chart from the Cache Related Projects ChartMuseum Harbor Chart Releaser S3 Plugin GCS Plugin Git Plugin Chapter 8. Helm Plugins and Starters Plugins Installing Third-Party Plugins Custom Subcommands Building a Plugin plugin.yaml Hooks Downloader Plugins Execution Environment Shell Completion Starters Converting a Chart to a Starter Making Starters Available to Helm Using Starters Extending Helm Further Appendix A. Chart API Versions API Version 2 The Chart.yaml File The Chart.lock File API Version 1 (legacy) The Chart.yaml File The requirements.yaml File (Legacy) The requirements.lock File (Legacy) Appendix B. Chart Repository API index.yaml The index.yaml Format When Is index.yaml Downloaded? When Is the Cached Version of index.yaml Used? .tgz Files When Are .tgz Files Downloaded? .prov Files When Are .prov Files Downloaded? Index About the Authors Colophon