helm-go

Helm Go Client

The Helm Go Client is a fluent client library for managing Helm charts and operating on resources deployed by Helm in Kubernetes.

The client has a low barrier to entry for existing helm users. The API is modeled on the helm CLI commands. Additionally, a custom Kubernetes client supports querying and filtering resources by specific Helm chart releases.

Installation

Helm-Go uses Go modules for dependency management. To add the client to your go module:

> GO111MODULE=on go get github.com/onosproject/helm-go

Usage

The primary API for the client is the Helm interface, which provides functions for setting up repositories, querying charts, managing chart releases, and operating on a release's resources in Kubernetes.

To create a Helm client, simply call helm.New():

import "github.com/onosproject/helm-go/pkg/helm"

client, err := helm.New()

By default, the client will be configured with the default namespace. You can optionally specify a different namespace within which to operate:

import "github.com/onosproject/helm-go/pkg/helm"

client, err := helm.New("onos")

The client exposes a series of sub-client interfaces which replicate the functionality of Helm CLI commands. Interfaces follow a common pattern, providing fluent builders for requests to the Kubernetes cluster. Requests are always executed by calling the Do() method.

Managing Repositories

The repository client wraps the functionality provided by the helm repo subcommands in the Helm CLI. Repositories can be added and removed from the repo registry. The repo client can be accessed by calling Repos() on the Helm client:

repos := client.Repos()

To add a repository to the registry, execute an Add request:

repo, err := client.Repos().
	Add("onos").
	URL("https://onos-helm-charts.onosproject.org").
	Username("jordan").
	Passsword("pA$$w0®D").
	Do()

To remove a repository, execute a Remove request:

err := client.Repos().
	Remove("onos").
	Do()

To list the repositories in the registry, call List:

repos, err := client.Repos().List()

To get a specific repository, use Get:

repo, err := client.Repos().Get("onos")

Accessing Charts

The chart client provides an interface similar to the repo client above, allowing users to access information regarding specific charts. The chart client can be accessed by calling Charts() on the Helm client:

charts := client.Charts()

To load a chart, use Get:

chart, err := client.Charts().Get("onos/onos-classic")

Managing Releases

The release client can be used to execute commands for installing, uninstalling, upgrading, etc your Helm charts. The release client is accessed by calling Releases() on the Helm client:

releases := client.Releases()

To get a list of releases call the List method:

releases, err := client.Releases().List()

To get a specific release by name, use the Get method:

release, err := client.Releases().Get("onos")

Release objects include a Status indicating the current status of the release:

switch release.Status {
case StatusPendingInstall:
	...
case StatusDeployed:
	...
case StatusUninstalled:
    ...
case StatusFailed:
    ...
default:
	...
}

To release a chart, execute an Install request:

release, err := client.Releases().
	Install("onos", "onos/onos-classic").
	Version("2.5.0").
	Do()

If the repository has not been added to the repo registry, repository settings can be provided within the install request:

release, err := client.Releases().
	Install("onos", "onos-classic").
	Repo("https://onos-helm-charts.onosproject.org").
	Username("jordan").
	Passsword("pA$$w0®D").
	Version("2.5.0").
	Do()

The Install request supports all the same options available through the Helm CLI. For example, you can Wait for the release to complete, set a Timeout, perform a DryRun, or enable all the other options available when installing a chart:

release, err := client.Releases().
	Install("onos", "onos/onos-classic").
	DryRun().
	Do()

release, err = client.Releases().
	Install("onos", "onos/onos-classic").
	Version("2.5.0").
	Wait().
	Timeout(5*time.Minute).
	Do()

The Set method mimics the format of the --set flag in the Helm CLI:

release, err := client.Releases().
	Install("onos", "onos/onos-classic").
	Version("2.5.0").
	Set("replicas", 3).
	Set("atomix.replicas", 3).
	Set("heap", "8G").
	Set("apps", []string{"org.onosproject.openflow", "org.onosproject.p4runtime"}).
	Do()

Values set using the Set method will override the default chart values. Nested values can be set using the same dot.notation used in the Helm CLI. Values can be of a scalar type, map, slice, or struct.

To uninstall a chart release, execute an Uninstall request:

err := client.Releases().
	Uninstall("onos").
	Do()

Querying Resources

Once a chart has been installed, the Release provides a release-scoped Kubernetes client for querying chart objects. The release-scoped client can be used to list resources created by the release. This can be helpful for writing integration tests:

// Get a list of pods created by the atomix-controller
pods, err := release.Client().CoreV1().Pods().List()
assert.NoError(t, err)

// Get the Atomix controller pod
pod := pods[0]

// Delete the pod
err := pod.Delete()
assert.NoError(t, err)

Additionally, Kubernetes objects that create and own other Kubernetes resources -- like Deployment, StatefulSet, Job, etc -- provide scoped clients that can be used to query the resources they own as well:

// Get the atomix-controller deployment
deps, err := release.Client().AppsV1().Deployments().List()
assert.NoError(t, err)
assert.Len(t, deps, 1)
dep := deps[0]

// Get the pods created by the controller deployment
pods, err := dep.CoreV1().Pods().List()
assert.NoError(t, err)
assert.Len(t, pods, 1)
pod := pods[0]

// Delete the controller pod
err = pod.Delete()
assert.NoError(t, err)

// Wait a minute for the controller deployment to recover
err = dep.Wait(1 * time.Minute)
assert.NoError(t, err)

// Verify the pod was recovered
pods, err := dep.CoreV1().Pods().List()
assert.NoError(t, err)
assert.Len(t, pods, 1)
assert.NotEqual(t, pod.Name, pods[0].Name)