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 7. Chart Repositories

No package manager is complete without a way to share and distribute the packages themselves. Organizations and vendors must have a way to publish packages for end users to download and consume. Likewise, end users must have a common way to fetch packages from a variety of sources.

Helm enables package distribution though a system called chart repositories. Chart repositories are simple HTTP(S) web services from which users can discover and download available charts. Conceptually, chart repositories are similar in design to Debian package repositories, Fedora package databases, or the Comprehensive Perl Archive Network (CPAN).

In this chapter, we will first dive deep into the internals of a chart repository. We will discuss the repository index and how to update it with new chart versions. After that, we will show how to set up a chart repository from scratch, how to secure one, and also show a real-world example of how to host a public chart repository using GitHub Pages for open source projects. After this, we will walk through the various helm repo commands and how to use them effectively.

Toward the end of the chapter, we will cover the next generation of chart repositories using Helm’s experimental Open Container Initiative (OCI) support. This bleeding-edge functionality added in Helm 3 allows users to store Helm charts in container registries alongside their container images.

Lastly, we will briefly describe some of the projects in the Helm ...