Helm on IT-CNE Cloud-Native Core

Helm overview

Mon, 01 Jan 0001 00:00:00 +0000

Ok, let’s start with Helm. First, you have to understand the following 3 Helm concepts: Chart, Repository and Release.

A Chart is a Helm package. It contains all of the resource definitions necessary to run an application, tool, or service inside of a Kubernetes cluster. Think of it like the Kubernetes equivalent of a Homebrew formula, an Apt dpkg, or a Yum RPM file.

A Repository is the place where charts can be collected and shared. It’s like Perl’s CPAN archive or the Fedora Package Database, but for Kubernetes packages.

CLI installation

Mon, 01 Jan 0001 00:00:00 +0000

This guide shows you how to install the helm CLI tool. helm can be installed either from source or from pre-built binary releases. We are going to use the pre-built releases. helm binaries can be found on Helm’s release page for the usual variety of operating systems.

Warning

If you do this training in our acend web based environment, no installation is required.

Task 1.2.12.2.1: Install CLI

Install the CLI for your Operating System

Create a chart

Mon, 01 Jan 0001 00:00:00 +0000

In this lab we are going to create our very first Helm chart and deploy it.

Task 1.2.12.3.7: Create Chart

First, let’s create our chart. Open your favorite terminal and make sure you’re in the workspace for this lab, e.g. cd ~/<workspace-kubernetes-training>:

helm create mychart

You will now find a mychart directory with the newly created chart. It already is a valid and fully functional chart which deploys an nginx instance. Have a look at the generated files and their content. For an explanation of the files, visit the Helm Developer Documentation. In a later section you’ll find all the information about Helm templates.

Generic Chart setup

Mon, 01 Jan 0001 00:00:00 +0000

In the following labs we are going to create our first Helm Charts with the help of Baloise’s Generic Chart and deploy them.

Baloise’s Generic Helm Chart is meant as a template and easy starting point to deploy common Kubernetes resource manifests. By declaring the Generic Chart as a dependency of your own Chart, you can make use of all the features the Generic Chart offers.

Task 2: Setup the dependency

So first, let’s create your own Chart. Open your favorite terminal and make sure you’re in the workspace for this lab, e.g. cd ~/<workspace-kubernetes-training>:

A first example using the Generic Chart

Mon, 01 Jan 0001 00:00:00 +0000

You’re now all set to begin with a first example!

Task 4: Create a `values.yaml` file

Still inside your mychart Helm Chart directory, open the already existing values.yaml file. Inside you’ll find a host of defined parameters. Delete them all.

Instead, fill in the following content:

first-example-app:
  replicaCount: 1
  image:
    repository: REGISTRY-URL/example/nginx-sample
    tag: latest
    pullPolicy: IfNotPresent
  ingress:
    controller: Route
    clusterName: CLUSTER-NAME
  network:
    http:
      servicePort: 8080
      ingress:
        clusterName: CLUSTER-NAME
  readinessProbe:
    httpGet:
      path: /
      port: 8080
    initialDelaySeconds: 5
    timeoutSeconds: 1
  resources:
    requests:
      cpu: 10m
      memory: 16Mi
    limits:
      cpu: 200m
      memory: 32Mi

Task 5: A first test

Before applying anything to the cluster, you should test if the current values have the desired effect. In order to do so, execute the following command:

Complex example

Mon, 01 Jan 0001 00:00:00 +0000

In this extended lab, we are going to deploy an existing, more complex application with a Helm chart from the Artifact Hub.

Artifact Hub

Check out Artifact Hub where you’ll find a huge number of different Helm charts. For this lab, we’ll use the WordPress chart by Bitnami, a publishing platform for building blogs and websites.

WordPress

As this WordPress Helm chart is published in Bitnami’s Helm repository, we’re first going to add it to our local repo list:

Generic Chart usage

Mon, 01 Jan 0001 00:00:00 +0000

You have now seen how to set up and use the Generic Chart. Now it’s your turn!

Task 1: Setup

Repeat the steps from Generic Chart setup in order to create a new Chart.

Note

Note the alias: line inside Chart.yaml. You can change this value to whatever you’d like, but you need to use the same name as first line inside your values.yaml!

This is also how you can use the Generic Chart multiple times if you have more than one app/component.

Helm on IT-CNE Cloud-Native Core

Helm overview

CLI installation

Task 1.2.12.2.1: Install CLI

Create a chart

Task 1.2.12.3.7: Create Chart

Generic Chart setup

Task 2: Setup the dependency

A first example using the Generic Chart

Task 4: Create a values.yaml file

Task 5: A first test

Complex example

Artifact Hub

WordPress

Generic Chart usage

Task 1: Setup

Task 4: Create a `values.yaml` file