Chapter 2. User tasks

2.1. Creating applications from installed Operators

This guide walks developers through an example of creating applications from an installed Operator using the OpenShift Container Platform web console.

2.1.1. Creating an etcd cluster using an Operator

This procedure walks through creating a new etcd cluster using the etcd Operator, managed by Operator Lifecycle Manager (OLM).

Prerequisites

  • Access to an OpenShift Container Platform 4.7 cluster.
  • The etcd Operator already installed cluster-wide by an administrator.

Procedure

  1. Create a new project in the OpenShift Container Platform web console for this procedure. This example uses a project called my-etcd.
  2. Navigate to the Operators → Installed Operators page. The Operators that have been installed to the cluster by the cluster administrator and are available for use are shown here as a list of cluster service versions (CSVs). CSVs are used to launch and manage the software provided by the Operator.

    Tip

    You can get this list from the CLI using:

    $ oc get csv
  3. On the Installed Operators page, click the etcd Operator to view more details and available actions.

    As shown under Provided APIs, this Operator makes available three new resource types, including one for an etcd Cluster (the EtcdCluster resource). These objects work similar to the built-in native Kubernetes ones, such as Deployment or ReplicaSet, but contain logic specific to managing etcd.

  4. Create a new etcd cluster:

    1. In the etcd Cluster API box, click Create instance.
    2. The next screen allows you to make any modifications to the minimal starting template of an EtcdCluster object, such as the size of the cluster. For now, click Create to finalize. This triggers the Operator to start up the pods, services, and other components of the new etcd cluster.
  5. Click on the example etcd cluster, then click the Resources tab to see that your project now contains a number of resources created and configured automatically by the Operator.

    Verify that a Kubernetes service has been created that allows you to access the database from other pods in your project.

  6. All users with the edit role in a given project can create, manage, and delete application instances (an etcd cluster, in this example) managed by Operators that have already been created in the project, in a self-service manner, just like a cloud service. If you want to enable additional users with this ability, project administrators can add the role using the following command:

    $ oc policy add-role-to-user edit <user> -n <target_project>

You now have an etcd cluster that will react to failures and rebalance data as pods become unhealthy or are migrated between nodes in the cluster. Most importantly, cluster administrators or developers with proper access can now easily use the database with their applications.

2.2. Installing Operators in your namespace

If a cluster administrator has delegated Operator installation permissions to your account, you can install and subscribe an Operator to your namespace in a self-service manner.

2.2.1. Prerequisites

2.2.2. Operator installation with OperatorHub

OperatorHub is a user interface for discovering Operators; it works in conjunction with Operator Lifecycle Manager (OLM), which installs and manages Operators on a cluster.

As a user with the proper permissions, you can install an Operator from OperatorHub using the OpenShift Container Platform web console or CLI.

During installation, you must determine the following initial settings for the Operator:

Installation Mode
Choose a specific namespace in which to install the Operator.
Update Channel
If an Operator is available through multiple channels, you can choose which channel you want to subscribe to. For example, to deploy from the stable channel, if available, select it from the list.
Approval Strategy

You can choose automatic or manual updates.

If you choose automatic updates for an installed Operator, when a new version of that Operator is available in the selected channel, Operator Lifecycle Manager (OLM) automatically upgrades the running instance of your Operator without human intervention.

If you select manual updates, when a newer version of an Operator is available, OLM creates an update request. As a cluster administrator, you must then manually approve that update request to have the Operator updated to the new version.

2.2.3. Installing from OperatorHub using the web console

You can install and subscribe to an Operator from OperatorHub using the OpenShift Container Platform web console.

Prerequisites

  • Access to an OpenShift Container Platform cluster using an account with Operator installation permissions.

Procedure

  1. Navigate in the web console to the Operators → OperatorHub page.
  2. Scroll or type a keyword into the Filter by keyword box to find the Operator you want. For example, type advanced to find the Advanced Cluster Management for Kubernetes Operator.

    You can also filter options by Infrastructure Features. For example, select Disconnected if you want to see Operators that work in disconnected environments, also known as restricted network environments.

  3. Select the Operator to display additional information.

    Note

    Choosing a Community Operator warns that Red Hat does not certify Community Operators; you must acknowledge the warning before continuing.

  4. Read the information about the Operator and click Install.
  5. On the Install Operator page:

    1. Choose a specific, single namespace in which to install the Operator. The Operator will only watch and be made available for use in this single namespace.
    2. Select an Update Channel (if more than one is available).
    3. Select Automatic or Manual approval strategy, as described earlier.
  6. Click Install to make the Operator available to the selected namespaces on this OpenShift Container Platform cluster.

    1. If you selected a Manual approval strategy, the upgrade status of the subscription remains Upgrading until you review and approve the install plan.

      After approving on the Install Plan page, the subscription upgrade status moves to Up to date.

    2. If you selected an Automatic approval strategy, the upgrade status should resolve to Up to date without intervention.
  7. After the upgrade status of the subscription is Up to date, select Operators → Installed Operators to verify that the cluster service version (CSV) of the installed Operator eventually shows up. The Status should ultimately resolve to InstallSucceeded in the relevant namespace.

    Note

    For the All namespaces…​ installation mode, the status resolves to InstallSucceeded in the openshift-operators namespace, but the status is Copied if you check in other namespaces.

    If it does not:

    1. Check the logs in any pods in the openshift-operators project (or other relevant namespace if A specific namespace…​ installation mode was selected) on the Workloads → Pods page that are reporting issues to troubleshoot further.

2.2.4. Installing from OperatorHub using the CLI

Instead of using the OpenShift Container Platform web console, you can install an Operator from OperatorHub using the CLI. Use the oc command to create or update a Subscription object.

Prerequisites

  • Access to an OpenShift Container Platform cluster using an account with Operator installation permissions.
  • Install the oc command to your local system.

Procedure

  1. View the list of Operators available to the cluster from OperatorHub:

    $ oc get packagemanifests -n openshift-marketplace

    Example output

    NAME                               CATALOG               AGE
    3scale-operator                    Red Hat Operators     91m
    advanced-cluster-management        Red Hat Operators     91m
    amq7-cert-manager                  Red Hat Operators     91m
    ...
    couchbase-enterprise-certified     Certified Operators   91m
    crunchy-postgres-operator          Certified Operators   91m
    mongodb-enterprise                 Certified Operators   91m
    ...
    etcd                               Community Operators   91m
    jaeger                             Community Operators   91m
    kubefed                            Community Operators   91m
    ...

    Note the catalog for your desired Operator.

  2. Inspect your desired Operator to verify its supported install modes and available channels:

    $ oc describe packagemanifests <operator_name> -n openshift-marketplace
  3. An Operator group, defined by an OperatorGroup object, selects target namespaces in which to generate required RBAC access for all Operators in the same namespace as the Operator group.

    The namespace to which you subscribe the Operator must have an Operator group that matches the install mode of the Operator, either the AllNamespaces or SingleNamespace mode. If the Operator you intend to install uses the AllNamespaces, then the openshift-operators namespace already has an appropriate Operator group in place.

    However, if the Operator uses the SingleNamespace mode and you do not already have an appropriate Operator group in place, you must create one.

    Note

    The web console version of this procedure handles the creation of the OperatorGroup and Subscription objects automatically behind the scenes for you when choosing SingleNamespace mode.

    1. Create an OperatorGroup object YAML file, for example operatorgroup.yaml:

      Example OperatorGroup object

      apiVersion: operators.coreos.com/v1
      kind: OperatorGroup
      metadata:
        name: <operatorgroup_name>
        namespace: <namespace>
      spec:
        targetNamespaces:
        - <namespace>

    2. Create the OperatorGroup object:

      $ oc apply -f operatorgroup.yaml
  4. Create a Subscription object YAML file to subscribe a namespace to an Operator, for example sub.yaml:

    Example Subscription object

    apiVersion: operators.coreos.com/v1alpha1
    kind: Subscription
    metadata:
      name: <subscription_name>
      namespace: openshift-operators 1
    spec:
      channel: <channel_name> 2
      name: <operator_name> 3
      source: redhat-operators 4
      sourceNamespace: openshift-marketplace 5

    1
    For AllNamespaces install mode usage, specify the openshift-operators namespace. Otherwise, specify the relevant single namespace for SingleNamespace install mode usage.
    2
    Name of the channel to subscribe to.
    3
    Name of the Operator to subscribe to.
    4
    Name of the catalog source that provides the Operator.
    5
    Namespace of the catalog source. Use openshift-marketplace for the default OperatorHub catalog sources.
  5. Create the Subscription object:

    $ oc apply -f sub.yaml

    At this point, OLM is now aware of the selected Operator. A cluster service version (CSV) for the Operator should appear in the target namespace, and APIs provided by the Operator should be available for creation.

Additional resources

2.2.5. Installing a specific version of an Operator

You can install a specific version of an Operator by setting the cluster service version (CSV) in a Subscription object.

Prerequisites

  • Access to an OpenShift Container Platform cluster using an account with Operator installation permissions
  • OpenShift CLI (oc) installed

Procedure

  1. Create a Subscription object YAML file that subscribes a namespace to an Operator with a specific version by setting the startingCSV field. Set the installPlanApproval field to Manual to prevent the Operator from automatically upgrading if a later version exists in the catalog.

    For example, the following sub.yaml file can be used to install the Red Hat Quay Operator specifically to version 3.4.0:

    Subscription with a specific starting Operator version

    apiVersion: operators.coreos.com/v1alpha1
    kind: Subscription
    metadata:
      name: quay-operator
      namespace: quay
    spec:
      channel: quay-v3.4
      installPlanApproval: Manual 1
      name: quay-operator
      source: redhat-operators
      sourceNamespace: openshift-marketplace
      startingCSV: quay-operator.v3.4.0 2

    1
    Set the approval strategy to Manual in case your specified version is superseded by a later version in the catalog. This plan prevents an automatic upgrade to a later version and requires manual approval before the starting CSV can complete the installation.
    2
    Set a specific version of an Operator CSV.
  2. Create the Subscription object:

    $ oc apply -f sub.yaml
  3. Manually approve the pending install plan to complete the Operator installation.