第 3 章 Helm CLI
3.1. Getting started with Helm 3 on OpenShift Container Platform
3.1.1. Understanding Helm
Helm is a software package manager that simplifies deployment of applications and services to OpenShift Container Platform clusters.
Helm uses a packaging format called charts. A Helm chart is a collection of files that describes the OpenShift Container Platform resources.
A running instance of the chart in a cluster is called a release. A new release is created every time a chart is installed on the cluster.
Each time a chart is installed, or a release is upgraded or rolled back, an incremental revision is created.
3.1.1.1. Key features
Helm provides the ability to:
- Search through a large collection of charts stored in the chart repository.
- Modify existing charts.
- Create your own charts with OpenShift Container Platform or Kubernetes resources.
- Package and share your applications as charts.
3.1.2. Installing Helm
The following section describes how to install Helm on different platforms using the CLI.
You can also find the URL to the latest binaries from the OpenShift Container Platform web console by clicking the ? icon in the upper-right corner and selecting Command Line Tools.
Prerequisites
- You have installed Go, version 1.13 or higher.
3.1.2.1. On Linux
Download the Helm binary and add it to your path:
# curl -L https://mirror.openshift.com/pub/openshift-v4/clients/helm/latest/helm-linux-amd64 -o /usr/local/bin/helm
Make the binary file executable:
# chmod +x /usr/local/bin/helm
Check the installed version:
$ helm version
Example output
version.BuildInfo{Version:"v3.0", GitCommit:"b31719aab7963acf4887a1c1e6d5e53378e34d93", GitTreeState:"clean", GoVersion:"go1.13.4"}
3.1.2.2. On Windows 7/8
-
Download the latest
.exefile and put in a directory of your preference. - Right click Start and click Control Panel.
- Select System and Security and then click System.
- From the menu on the left, select Advanced systems settings and click Environment Variables at the bottom.
- Select Path from the Variable section and click Edit.
-
Click New and type the path to the folder with the
.exefile into the field or click Browse and select the directory, and click OK.
3.1.2.3. On Windows 10
-
Download the latest
.exefile and put in a directory of your preference. -
Click Search and type
envorenvironment. - Select Edit environment variables for your account.
- Select Path from the Variable section and click Edit.
- Click New and type the path to the directory with the exe file into the field or click Browse and select the directory, and click OK.
3.1.2.4. On MacOS
Download the Helm binary and add it to your path:
# curl -L https://mirror.openshift.com/pub/openshift-v4/clients/helm/latest/helm-darwin-amd64 -o /usr/local/bin/helm
Make the binary file executable:
# chmod +x /usr/local/bin/helm
Check the installed version:
$ helm version
Example output
version.BuildInfo{Version:"v3.0", GitCommit:"b31719aab7963acf4887a1c1e6d5e53378e34d93", GitTreeState:"clean", GoVersion:"go1.13.4"}
3.1.3. Installing a Helm chart on an OpenShift Container Platform cluster
Prerequisites
- You have a running OpenShift Container Platform cluster and you have logged into it.
- You have installed Helm.
Procedure
Create a new project:
$ oc new-project mysql
Add a repository of Helm charts to your local Helm client:
$ helm repo add stable https://kubernetes-charts.storage.googleapis.com/
Example output
"stable" has been added to your repositories
Update the repository:
$ helm repo update
Install an example MySQL chart:
$ helm install example-mysql stable/mysql
Verify that the chart has installed successfully:
$ helm list
Example output
NAME NAMESPACE REVISION UPDATED STATUS CHART APP VERSION example-mysql mysql 1 2019-12-05 15:06:51.379134163 -0500 EST deployed mysql-1.5.0 5.7.27
3.1.4. Creating a custom Helm chart on OpenShift Container Platform
Procedure
Create a new project:
$ oc new-project nodejs-ex-k
Download an example Node.js chart that contains OpenShift Container Platform objects:
$ git clone https://github.com/redhat-developer/redhat-helm-charts
Go to the directory with the sample chart:
$ cd redhat-helm-charts/alpha/nodejs-ex-k/
Edit the
Chart.yamlfile and add a description of your chart:apiVersion: v2 1 name: nodejs-ex-k 2 description: A Helm chart for OpenShift 3 icon: https://static.redhat.com/libs/redhat/brand-assets/latest/corp/logo.svg 4
Verify that the chart is formatted properly:
$ helm lint
Example output
[INFO] Chart.yaml: icon is recommended 1 chart(s) linted, 0 chart(s) failed
Navigate to the previous directory level:
$ cd ..
Install the chart:
$ helm install nodejs-chart nodejs-ex-k
Verify that the chart has installed successfully:
$ helm list
Example output
NAME NAMESPACE REVISION UPDATED STATUS CHART APP VERSION nodejs-chart nodejs-ex-k 1 2019-12-05 15:06:51.379134163 -0500 EST deployed nodejs-0.1.0 1.16.0
