Deploy helm charts with go lang

What is Helm ?

Helm is designed to simplify the deployment and management of complex application workloads in Kubernetes. It functions similarly to a package manager for Kubernetes, where the packages are known as Helm Charts. A Helm Chart combines a template file, which outlines the Kubernetes resources to be deployed, and a values file that provides the necessary configuration for the template. The templating system in Helm Charts allows for package reusability.

The Helm go SDK ?

Helm includes a convenient CLI, a robust command-line tool that helps end-users manage all stages of a Chart’s lifecycle. However, using the CLI for programmatically installing Helm Charts on a Kubernetes cluster is not ideal for building a reliable and predictable application. Fortunately, the Helm developers designed the CLI as an interface for the Go SDK, which I will use for this purpose.

Installing and Using Helm client ….

First we need to install go-helm-client, we can use below command and it will add this module into go.mod file.

$ go get github.com/mittwald/go-helm-client

Now we can import this like helmcilent "github.com/mittwald/go-helm-client" and use this in our application.

package main

import (
  "fmt"
  "os"
  helmclient "github.com/mittwald/go-helm-client"
)


func GetHelmClient(kubeConfig string, namespace string) (helmclient.Client) {

 opt := &helmclient.KubeConfClientOptions{
  Options: &helmclient.Options{
   Namespace:        namespace, // Change this to the namespace you wish to install the chart in.
   RepositoryCache:  "/tmp/.helmcache",
   RepositoryConfig: "/tmp/.helmrepo",
   Debug:            true,
  },
  KubeContext: "",
  KubeConfig:  []byte(kubeConfig),
 }

 helmClient, err := helmclient.NewClientFromKubeConf(opt)
 if err != nil {
  fmt.Printf("Failed to initialize Helm Client: %v", err)
  return nil
 }
 return helmClient
}

func main() {
 dirname, err := os.UserHomeDir()
 kubeConfig, err := os.ReadFile(fmt.Sprintf("%s/.kube/config", dirname))
 if err != nil {
  t.Fatalf("Not able to read File: %v", err)
 }

 helmClient := helmc.GetHelmClient(string(kubeConfig), "default")
}

you can run and test this on your local Kubernetes if your docker-kubernetes is enabled. providing kubeConfig and namespace you can create helmClient object and using that you can perform helm operations.

Here are list of methods that you are able to call using this client.

type Client interface {
   AddOrUpdateChartRepo(entry repo.Entry) error
   UpdateChartRepos() error
   InstallOrUpgradeChart(ctx context.Context, spec *ChartSpec, opts *GenericHelmOptions) (*release.Release, error)
   InstallChart(ctx context.Context, spec *ChartSpec, opts *GenericHelmOptions) (*release.Release, error)
   UpgradeChart(ctx context.Context, spec *ChartSpec, opts *GenericHelmOptions) (*release.Release, error)
   ListDeployedReleases() ([]*release.Release, error)
   ListReleasesByStateMask(action.ListStates) ([]*release.Release, error)
   GetRelease(name string) (*release.Release, error)
   // RollBack is an interface to abstract a rollback action.
   RollBack
   GetReleaseValues(name string, allValues bool) (map[string]interface{}, error)
   GetSettings() *cli.EnvSettings
   GetProviders() getter.Providers
   UninstallRelease(spec *ChartSpec) error
   UninstallReleaseByName(name string) error
   TemplateChart(spec *ChartSpec, options *HelmTemplateOptions) ([]byte, error)
   LintChart(spec *ChartSpec) error
   SetDebugLog(debugLog action.DebugLog)
   ListReleaseHistory(name string, max int) ([]*release.Release, error)
   GetChart(chartName string, chartPathOptions *action.ChartPathOptions) (*chart.Chart, string, error)
   RunChartTests(releaseName string) (bool, error)
}

Let me give you an example how you can use the helmClient and installChart from local directory.

import (
  "context"
)

func main() {
  // using old helmClient that we have created before
  helmClient := helmc.GetHelmClient(string(kubeConfig), "default")

  // Define the chart to be installed
  chartSpec := ChartSpec{
   ReleaseName: "nginx",
   ChartName:   "/tmp/nginx",
   Namespace:   "default",
   UpgradeCRDs: true,
   Wait:        true,
  }

  // Install a chart release.
  // Note that helmclient.Options.Namespace should ideally match 
  // the namespace in chartSpec.Namespace.
  if _, err := helmClient.InstallChart(context.Background(), &chartSpec, 
  nil); err != nil {
   panic(err)
  }
}

You can also provide a zip or link to zip file as value in ChartName.

If you want more example you can look into this. https://github.com/mittwald/go-helm-client/blob/v0.12.9/client_test.go

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