book

Learning Helm

by Matt Butcher, Matt Farina, Josh Dolitsky

January 2021

Beginner to intermediate

212 pages

5h 38m

English

O'Reilly Media, Inc.

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Who Should Read This BookWhy We Wrote This BookNavigating This BookConventions Used in This BookUsing Code ExamplesO’Reilly Online LearningHow to Contact UsAcknowledgments
The Cloud Native EcosystemContainers and MicroservicesSchedules and KubernetesHelm’s GoalsFrom Zero to KubernetesPackage ManagementSecurity, Reusability, and ConfigurabilityHelm’s ArchitectureKubernetes ResourcesChartsResources, Installations, and ReleasesA Brief Note About Helm 2Conclusion
Installing and Configuring the Helm ClientInstalling a Prebuilt BinaryGuidance on Building from SourceWorking with Kubernetes ClustersGetting Started with HelmAdding a Chart RepositorySearching a Chart RepositoryInstalling a PackageConfiguration at Installation TimeListing Your InstallationsUpgrading an InstallationConfiguration Values and UpgradesUninstalling an InstallationHow Helm Stores Release InformationConclusion
Templating and Dry RunsThe --dry-run FlagThe helm template CommandLearning About a ReleaseRelease RecordsListing ReleasesFind Details of a Release with helm getHistory and RollbacksKeeping History and Rolling BackA Deep Dive into Installs and UpgradesThe --generate-name and --name-template FlagsThe --create-namespace FlagUsing helm upgrade --installThe --wait and --atomic FlagsUpgrading with --force and --cleanup-on-failConclusion
The Chart Creation CommandThe Chart.yaml FileModifying TemplatesThe DeploymentUsing the Values FileContainer ImagesExposing ServicesResource LimitsPackaging the ChartLinting ChartsConclusion
The Template SyntaxActionsInformation Helm Passes to TemplatesPipelinesTemplate FunctionsMethodsQuerying Kubernetes Resources In Chartsif/else/withVariablesLoopsNamed TemplatesStructuring Your Templates for MaintainabilityDebugging TemplatesDry RunGetting Installed ManifestsLinting ChartsConclusion
Chart DependenciesConditional Flags for Enabling DependenciesImporting Values from Child to Parent ChartsLibrary ChartsSchematizing Values FilesHooksAdding Tests to ChartsHelm TestChart Testing ToolSecurity ConsiderationsCustom Resource DefinitionsConclusion
The Repository IndexAn Example of a Chart Repository IndexGenerating an IndexAdding to an Existing IndexSetting Up a Chart RepositoryA Simple Chart Repository with PythonSecuring a Chart RepositoryReal-World Example: Using GitHub PagesUsing Chart RepositoriesAdding a RepositoryDownloading ChartsListing RepositoriesUpdating RepositoriesRemoving a RepositoryExperimental OCI SupportEnabling OCI SupportRunning a Local RegistryLogging In to a RegistryLogging Out of a RegistryStoring a Chart in the CacheListing Charts in the CacheExporting a Chart from the CachePushing a Chart to the RegistryPulling a Chart from the RegistryRemoving a Chart from the CacheRelated ProjectsChartMuseumHarborChart ReleaserS3 PluginGCS PluginGit Plugin
PluginsInstalling Third-Party PluginsCustom SubcommandsBuilding a Pluginplugin.yamlHooksDownloader PluginsExecution EnvironmentShell CompletionStartersConverting a Chart to a StarterMaking Starters Available to HelmUsing StartersExtending Helm Further
API Version 2The Chart.yaml FileThe Chart.lock FileAPI Version 1 (legacy)The Chart.yaml FileThe requirements.yaml File (Legacy)The requirements.lock File (Legacy)

index.yamlThe index.yaml FormatWhen Is index.yaml Downloaded?When Is the Cached Version of index.yaml Used?.tgz FilesWhen Are .tgz Files Downloaded?.prov FilesWhen Are .prov Files Downloaded?

Content preview from Learning Helm

Chapter 4. Building a Chart

Charts are at the heart of Helm. In addition to installing them into a Kubernetes cluster or managing the instances of charts you’ve installed, you can build new charts or alter existing ones. In the next three chapters we will cover a lot of details about charts including creating them, the elements inside them, templating Kubernetes manifests, testing charts, dependencies, and more.

In this chapter you will learn how to create a new chart and learn about the many parts of a chart. This will include the use of several built-in commands that can help you in the chart development process.

Charts are the packages Helm works with. They are conceptually similar to Debian packages used by APT or Formula used by Homebrew for macOS. The conceptual similarity is where the similarities end. Charts are designed to target Kubernetes as a platform that has its own unique style. At the heart of charts are templates to generate Kubernetes manifests that can be installed and managed in a cluster.

Before we dig into templates in Chapter 5, let’s start by creating a basic fully functional chart. To do that we will cover an example chart named anvil. Using that chart you will learn about using Helm to generate a chart, the structure of charts and files within them, packaging charts, and linting charts. Reference the online source for this chart at https://github.com/Masterminds/learning-helm/tree/main/chapter4/anvil.