Chapter 4. Working with Helm charts

4.1. 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.

4.1.1. 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.

4.1.2. Red Hat Certification of Helm charts for OpenShift

You can choose to verify and certify your Helm charts by Red Hat for all the components you will be deploying on the Red Hat OpenShift Container Platform. Charts go through an automated Red Hat OpenShift certification workflow that guarantees security compliance as well as best integration and experience with the platform. Certification assures the integrity of the chart and ensures that the Helm chart works seamlessly on Red Hat OpenShift clusters.

4.1.3. Additional resources

4.2. 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.

4.2.1. On Linux

  1. 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
  2. Make the binary file executable:

    # chmod +x /usr/local/bin/helm
  3. Check the installed version:

    $ helm version

    Example output

    version.BuildInfo{Version:"v3.0", GitCommit:"b31719aab7963acf4887a1c1e6d5e53378e34d93", GitTreeState:"clean", GoVersion:"go1.13.4"}

4.2.2. On Windows 7/8

  1. Download the latest .exe file and put in a directory of your preference.
  2. Right click Start and click Control Panel.
  3. Select System and Security and then click System.
  4. From the menu on the left, select Advanced systems settings and click Environment Variables at the bottom.
  5. Select Path from the Variable section and click Edit.
  6. Click New and type the path to the folder with the .exe file into the field or click Browse and select the directory, and click OK.

4.2.3. On Windows 10

  1. Download the latest .exe file and put in a directory of your preference.
  2. Click Search and type env or environment.
  3. Select Edit environment variables for your account.
  4. Select Path from the Variable section and click Edit.
  5. 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.

4.2.4. On MacOS

  1. 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
  2. Make the binary file executable:

    # chmod +x /usr/local/bin/helm
  3. Check the installed version:

    $ helm version

    Example output

    version.BuildInfo{Version:"v3.0", GitCommit:"b31719aab7963acf4887a1c1e6d5e53378e34d93", GitTreeState:"clean", GoVersion:"go1.13.4"}

4.3. Configuring custom Helm chart repositories

You can install Helm charts on an OpenShift Container Platform cluster using the following methods:

  • The CLI.
  • The Developer perspective of the web console.

The Developer Catalog, in the Developer perspective of the web console, displays the Helm charts available in the cluster. By default, it lists the Helm charts from the Red Hat OpenShift Helm chart repository. For a list of the charts, see the Red Hat Helm index file.

As a cluster administrator, you can add multiple Helm chart repositories, apart from the default one, and display the Helm charts from these repositories in the Developer Catalog.

4.3.1. 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

  1. Create a new project:

    $ oc new-project mysql
  2. 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

  3. Update the repository:

    $ helm repo update
  4. Install an example MySQL chart:

    $ helm install example-mysql stable/mysql
  5. 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

4.3.2. Installing Helm charts using the Developer perspective

You can use either the Developer perspective in the web console or the CLI to select and install a chart from the Helm charts listed in the Developer Catalog. You can create Helm releases by installing Helm charts and see them in the Developer perspective of the web console.

Prerequisites

Procedure

To create Helm releases from the Helm charts provided in the Developer Catalog:

  1. In the Developer perspective, navigate to the +Add view and select a project. Then click Helm Chart option to see all the Helm Charts in the Developer Catalog.
  2. Select a chart and read the description, README, and other details about the chart.
  3. Click Install Helm Chart.

    Figure 4.1. Helm charts in developer catalog

    odc helm chart devcatalog
  4. In the Install Helm Chart page:

    1. Enter a unique name for the release in the Release Name field.
    2. Select the required chart version from the Chart Version drop-down list.
    3. Configure your Helm chart by using the Form View or the YAML View.

      Note

      Where available, you can switch between the YAML View and Form View. The data is persisted when switching between the views.

    4. Click Install to create a Helm release. You will be redirected to the Topology view where the release is displayed. If the Helm chart has release notes, the chart is pre-selected and the right panel displays the release notes for that release.

You can upgrade, rollback, or uninstall a Helm release by using the Actions button on the side panel or by right-clicking a Helm release.

4.3.3. Using Helm in the web terminal

You can use Helm by initializing the web terminal in the Developer perspective of the web console. For more information, see Using the web terminal.

4.3.4. Creating a custom Helm chart on OpenShift Container Platform

Procedure

  1. Create a new project:

    $ oc new-project nodejs-ex-k
  2. Download an example Node.js chart that contains OpenShift Container Platform objects:

    $ git clone https://github.com/redhat-developer/redhat-helm-charts
  3. Go to the directory with the sample chart:

    $ cd redhat-helm-charts/alpha/nodejs-ex-k/
  4. Edit the Chart.yaml file 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
    1
    The chart API version. It should be v2 for Helm charts that require at least Helm 3.
    2
    The name of your chart.
    3
    The description of your chart.
    4
    The URL to an image to be used as an icon.
  5. 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

  6. Navigate to the previous directory level:

    $ cd ..
  7. Install the chart:

    $ helm install nodejs-chart nodejs-ex-k
  8. 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

4.3.5. Adding custom Helm chart repositories

As a cluster administrator, you can add custom Helm chart repositories to your cluster and enable access to the Helm charts from these repositories in the Developer Catalog.

Procedure

  1. To add a new Helm Chart Repository, you must add the Helm Chart Repository custom resource (CR) to your cluster.

    Sample Helm Chart Repository CR

    apiVersion: helm.openshift.io/v1beta1
    kind: HelmChartRepository
    metadata:
      name: <name>
    spec:
     # optional name that might be used by console
     # name: <chart-display-name>
      connectionConfig:
        url: <helm-chart-repository-url>

    For example, to add an Azure sample chart repository, run:

    $ cat <<EOF | oc apply -f -
    apiVersion: helm.openshift.io/v1beta1
    kind: HelmChartRepository
    metadata:
      name: azure-sample-repo
    spec:
      name: azure-sample-repo
      connectionConfig:
        url: https://raw.githubusercontent.com/Azure-Samples/helm-charts/master/docs
    EOF
  2. Navigate to the Developer Catalog in the web console to verify that the Helm charts from the chart repository are displayed.

    For example, use the Chart repositories filter to search for a Helm chart from the repository.

    Figure 4.2. Chart repositories filter

    odc helm chart repo filter
    Note

    If a cluster administrator removes all of the chart repositories, then you cannot view the Helm option in the +Add view, Developer Catalog, and left navigation panel.

4.3.6. Creating credentials and CA certificates to add Helm chart repositories

Some Helm chart repositories need credentials and custom certificate authority (CA) certificates to connect to it. You can use the web console as well as the CLI to add credentials and certificates.

Procedure

To configure the credentials and certificates, and then add a Helm chart repository using the CLI:

  1. In the openshift-config namespace, create a ConfigMap object with a custom CA certificate in PEM encoded format, and store it under the ca-bundle.crt key within the config map:

    $ oc create configmap helm-ca-cert \
    --from-file=ca-bundle.crt=/path/to/certs/ca.crt \
    -n openshift-config
  2. In the openshift-config namespace, create a Secret object to add the client TLS configurations:

    $ oc create secret tls helm-tls-configs \
    --cert=/path/to/certs/client.crt \
    --key=/path/to/certs/client.key \
    -n openshift-config

    Note that the client certificate and key must be in PEM encoded format and stored under the keys tls.crt and tls.key, respectively.

  3. Add the Helm repository as follows:

    $ cat <<EOF | oc apply -f -
    apiVersion: helm.openshift.io/v1beta1
    kind: HelmChartRepository
    metadata:
      name: <helm-repository>
    spec:
      name: <helm-repository>
      connectionConfig:
        url: <URL for the Helm repository>
        tlsConfig:
            name: helm-tls-configs
        ca:
    	name: helm-ca-cert
    EOF

    The ConfigMap and Secret are consumed in the HelmChartRepository CR using the tlsConfig and ca fields. These certificates are used to connect to the Helm repository URL.

  4. By default, all authenticated users have access to all configured charts. However, for chart repositories where certificates are needed, you must provide users with read access to the helm-ca-cert config map and helm-tls-configs secret in the openshift-config namespace, as follows:

    $ cat <<EOF | kubectl apply -f -
    apiVersion: rbac.authorization.k8s.io/v1
    kind: Role
    metadata:
      namespace: openshift-config
      name: helm-chartrepos-tls-conf-viewer
    rules:
    - apiGroups: [""]
      resources: ["configmaps"]
      resourceNames: ["helm-ca-cert"]
      verbs: ["get"]
    - apiGroups: [""]
      resources: ["secrets"]
      resourceNames: ["helm-tls-configs"]
      verbs: ["get"]
    ---
    kind: RoleBinding
    apiVersion: rbac.authorization.k8s.io/v1
    metadata:
      namespace: openshift-config
      name: helm-chartrepos-tls-conf-viewer
    subjects:
      - kind: Group
        apiGroup: rbac.authorization.k8s.io
        name: 'system:authenticated'
    roleRef:
      apiGroup: rbac.authorization.k8s.io
      kind: Role
      name: helm-chartrepos-tls-conf-viewer
    EOF

4.3.7. Filtering Helm Charts by their certification level

You can filter Helm charts based on their certification level in the Developer Catalog.

Procedure

  1. In the Developer perspective, navigate to the +Add view and select a project.
  2. From the Developer Catalog tile, select the Helm Chart option to see all the Helm charts in the Developer Catalog.
  3. Use the filters to the left of the list of Helm charts to filter the required charts:

    • Use the Chart Repositories filter to filter charts provided by Red Hat Certification Charts or OpenShift Helm Charts.
    • Use the Source filter to filter charts sourced from Partners, Community, or Red Hat. Certified charts are indicated with the ( odc verified icon ) icon.
Note

The Source filter will not be visible when there is only one provider type.

You can now select the required chart and install it.

4.3.8. Disabling Helm Chart repositories

You can disable Helm Charts from a particular Helm Chart Repository in the catalog by setting the disabled property in the HelmChartRepository custom resource to true.

Procedure

  • To disable a Helm Chart repository by using CLI, add the disabled: true flag to the custom resource. For example, to remove an Azure sample chart repository, run:

    $ cat <<EOF | oc apply -f -
    apiVersion: helm.openshift.io/v1beta1
    kind: HelmChartRepository
    metadata:
      name: azure-sample-repo
    spec:
      connectionConfig:
       url:https://raw.githubusercontent.com/Azure-Samples/helm-charts/master/docs
      disabled: true
    EOF
  • To disable a recently added Helm Chart repository by using Web Console:

    1. Go to Custom Resource Definitions and search for the HelmChartRepository custom resource.
    2. Go to Instances, find the repository you want to disable, and click its name.
    3. Go to the YAML tab, add the disabled: true flag in the spec section, and click Save.

      Example

      spec:
        connectionConfig:
          url: <url-of-the-repositoru-to-be-disabled>
        disabled: true

      The repository is now disabled and will not appear in the catalog.

4.4. Working with Helm releases

You can use the Developer perspective in the web console to upgrade, rollback, or uninstall a Helm release.

4.4.1. Prerequisites

4.4.2. Upgrading a Helm release

You can upgrade a Helm release to upgrade to a new chart version or update your release configuration.

Procedure

  1. In the Topology view, select the Helm release to see the side panel.
  2. Click ActionsUpgrade Helm Release.
  3. In the Upgrade Helm Release page, select the Chart Version you want to upgrade to, and then click Upgrade to create another Helm release. The Helm Releases page displays the two revisions.

4.4.3. Rolling back a Helm release

If a release fails, you can rollback the Helm release to a previous version.

Procedure

To rollback a release using the Helm view:

  1. In the Developer perspective, navigate to the Helm view to see the Helm Releases in the namespace.
  2. Click the Options menu kebab adjoining the listed release, and select Rollback.
  3. In the Rollback Helm Release page, select the Revision you want to rollback to and click Rollback.
  4. In the Helm Releases page, click on the chart to see the details and resources for that release.
  5. Go to the Revision History tab to see all the revisions for the chart.

    Figure 4.3. Helm revision history

    odc helm revision history
  6. If required, you can further use the Options menu kebab adjoining a particular revision and select the revision to rollback to.

4.4.4. Uninstalling a Helm release

Procedure

  1. In the Topology view, right-click the Helm release and select Uninstall Helm Release.
  2. In the confirmation prompt, enter the name of the chart and click Uninstall.