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 8. Helm Plugins and Starters

As we’ve seen throughout this book, Helm has plenty of features and methods that aid in delivering applications on Kubernetes. However, it is also possible to customize and extend the functionality provided by Helm.

In this chapter we will discuss two ways to further enhance and customize your usage of Helm: plugins and starters.

Plugins allow you to add extra functionality to Helm and integrate seamlessly with the CLI, making them a popular choice for users with unique workflow requirements. There are a number of third-party plugins available online for common use cases, such as secrets management. In addition, plugins are incredibly easy to build on your own for unique, one-off tasks.

Starters expand the possibilities of using helm create to generate new Helm charts for different types of applications. For example, you might have a Helm chart built for an internal microservice that fits perfectly as an example for future microservices. You could convert the chart into a starter, which you can then use each time you begin a new project with similar requirements.

By leveraging plugins and starters, we can build on top of Helm’s out-of-the-box functionality to simplify and automate everyday workflow tasks.

Plugins

Helm plugins are external tools that are accessible directly from the Helm CLI. They allow you to add custom subcommands to Helm without making any modifications to Helm’s Go source code. This is similar in design to how plugin systems ...