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

Appendix A. Chart API Versions

This appendix covers the differences between chart API versions 2 and 1 (legacy).

The chart API version is specified in each chart’s Chart.yaml file and is used by Helm to determine how to parse the chart and which feature sets are made available.

For new charts, API version 2 should generally be used. However, many publicly available charts were created prior to the genesis of API version 2, and use 1, the legacy API version. Here we will go into detail on each of these API versions and the ways in which they are different.

API Version 2

Chart API version 2 is the current API version that was introduced in Helm 3. This is the default API version used when new charts are created using helm create.

Charts using API version 2 are guaranteed to be supported by Helm 3, but not necessarily by Helm 2. If you are only planning to support Helm 3 and above, it is recommended to just use this API version.

The Chart.yaml File

The following is an example of a Chart.yaml file for a chart using API version 2:

apiVersion: v2 
name: lemon
version: 1.2.3
type: application
description: When life gives you lemons, do the DevOps
appVersion: 2.0.0
home: https://example.com
icon: https://example.com/img/lemon.png
sources:
  - https://github.com/myorg/mychart
keywords:
  - fruit
  - citrus
maintainers:
  - name: Carly Jenkins
    email: carly@mail.cj.example.com
    url: https://cj.example.com ...