Difficulty: beginner
Estimated Time: 30 minutes

In the previous learning modules, we covered how to easily create the following types of Operators with the Operator SDK:

  • Go: Ideal for traditional software development teams that want to get to a fully auto-pilot Operator. It gives you the ability to leverage the same Kubernetes libraries the upstream projects uses under the hood. Check out the Go Getting Started guide.

  • Ansible: Useful for infrastructure-focused teams that have investment in Ansible modules but want to use them in a Kubernetes-native way. Also great for using Ansible to configure off-cluster objects like hardware load balancers. Check out the Ansible Getting Started guide.

We will now focus on the easiest way to get started developing an Operator:

  • Helm: Useful for securely running Helm charts without Tiller and it doesn’t rely on manual invocation of Helm to reconfigure your apps. Check out the Helm Operator Getting Started guide for more information.

Creating a Memcached Operator from a Helm Chart

In this tutorial, we will create a Memcached Operator from an existing Memcached Helm Chart.

Memcached is a Free & open source, high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load.

Let's begin!

Thank you for taking a closer look at Operator SDK's Helm Operator. For more information, check out the links below:



Operator SDK with Helm

Step 1 of 7

Initialize the Project

Let's begin my creating a new project called myproject:

oc new-project myproject

Memcached is an in-memory key-value store for small chunks of arbitrary data (strings, objects) from results of database calls, API calls, or page rendering.

Let's now create a new directory for our project:

mkdir -p $HOME/projects/memcached-operator

Navigate to the directory:

cd $HOME/projects/memcached-operator

Create a new Helm-based Operator SDK project for the Memcached Operator:

operator-sdk init --plugins helm --domain example.com

For Helm-based projects, operator-sdk init also generates the RBAC rules in config/rbac/role.yaml based on the resources that would be deployed by the chart’s default manifest. Be sure to double check that the rules generated in config/rbac/role.yaml meet the operator’s permission requirements.

To learn more about the project directory structure, see the project layout doc.

Use an existing chart

Instead of creating your project with a boilerplate Helm chart, you can also use --helm-chart, --helm-chart-repo, and --helm-chart-version to use an existing chart, either from your local filesystem or a remote chart repository.

Automatically fetch the Memcached Helm Chart and generate the CRD/API:

operator-sdk create api --helm-chart memcached --helm-chart-repo=https://charts.helm.sh/stable

Project Scaffolding Layout

After creating a new operator project the directory has numerous generated folders and files. The following table describes a basic rundown of each generated file/directory.

File/Folders Purpose
config Kustomize YAML definitions required to launch our controller on a cluster. It is the target directory to hold our CustomResourceDefinitions, RBAC configuration, and WebhookConfigurations.
Dockerfile The container build file used to build your Ansible Operator container image.
helm-charts The location for the specified helm-charts.
Makefile Make targets for building and deploying your controller.
PROJECT Kubebuilder metadata for scaffolding new components.
watches.yaml Contains Group, Version, Kind, and desired chart.