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07-extensions.md

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Extensions to OpenShift using OperatorHub

The documentation provides a lot of information on what operators are as well as details on the OperatorHub and how to add operators to the cluster.

The documentation provides an example of how to both install the etcd Operator as well as how to create an application from an installed operator.

The example below describes how to do the same with Couchbase. Couchbase is a powerful NoSQL database.

Create a Project

Before you get started, create a project for what you're about to do with Couchbase. You can either do it from the command line:

oc new-project mycouchbase

or create it from the web console.

Installing an Extension

Open the OpenShift web console, click to "Catalog", then "OperatorHub". At the top of the page, in the Project selector, choose mycouchbase.

Search or browse to the Couchbase Operator and click it. The description lays out the notable features of the Operator. Go ahead and click "Install" to deploy the Operator on to the cluster. It may take several moments after clicking "Install" before the Subscription page shows up.

Installation Mode

Operators can be enabled for all Projects across the cluster or only within specific namespaces. Not all Operators support each of these installation methods. The Couchbase operator only supports installation for a specific namespace. Make sure mycouchbase is selected to match the project you created earlier.

Update Channel

Each Operator publisher can create channels for their software, to give administrators more control over the versions that are installed. In this case, Couchbase only has a "preview" channel.

Update Approval Strategy

If Operator creators enable their operators to update the deployed solutions, Operator Lifecycle Manager is able to automatically apply those updates. Cluster administrators can decide whether or not OLM should or should not automatically apply updates. In the future, when Couchbase releases an updated operator to the "preview" channel, you can decide whether you want to approve each update, or have it happen automatically. Choose "Automatic" for now.

After clicking "Subscribe", the Couchbase entry will now show that it is "Installed".

Note: While the Operator Hub page indicates that the operator is "installed", really it is indicating that the Operator is configured to be installed. It may take several minutes for OpenShift to pull in the Operator to the cluster. You can check on the status of this operator with the following command:

oc get pod -all-namespaces | grep couch

You will likely see the Couchbase operator pod in ContainerCreating status if you look very soon after finishing the installation/subscription process.

Using Secrets

The Couchbase operator is capable of installing and managing a Couchbase cluster for you. But, before it can do that, it has a prerequisite for a Kubernetes secret that it can use to configure the username and password for the cluster. You have a few ways to create this secret.

  1. You can create a key/value secret with a username and password key in the OpenShift web console by navigating to "Workloads" and then "Secrets". Make sure the Project selector is set to mycouchbase. Finally, you can click "Create" and choose "Key/Value Secret".

  2. You can make sure the Project selector is set to mycouchbase and then click "+ Add" at the upper right-hand area of the web console, and then choose "Import YAML". Paste the following YAML into the form (the username is "couchbase" and the password is "securepassword"):

    apiVersion: v1
data:
  password: c2VjdXJlcGFzc3dvcmQ=
  username: Y291Y2hiYXNl
kind: Secret
metadata:
  name: cb-example-auth
  namespace: mycouchbase
type: Opaque

  3. You can create the secret directly using the following command:

    oc create -f https://raw.githubusercontent.com/openshift/training/master/assets/cb-example-auth.yaml

Ultimately, you want a secret with the username couchbase and the password securepassword (both example #2/#3 above use that).

Using an Installed Operator

Regular users will use the "Developer Catalog" menu to add shared apps, services, or source-to-image builders to projects. Navigate to the "Developer Catalog" and, at the top of the page, again make sure you select mycouchbase from the Project dropdown. You should see that the Couchbase operator is available. If you choose a different Project, you should also notice that the Couchbase operator is not available in other Projects.

Click on the Couchbase Cluster tile, which is a capability that the Operator has extended our OpenShift cluster to support. Operators can expose more than one capability. For example, the MongoDB Operator exposes three common configurations of its database (and you would see three different MongoDB tiles).

Deploy an instance of Couchbase by clicking the "Create" button in the top left. The YAML editor has been pre-filled with a set of defaults for the resulting Couchbase cluster. One of those defaults is a reference to the Secret you created earlier.

Changing Couchbase Parameters

The Couchbase Operator sets up a highly available cluster for us. Your YAML should look like the following:

apiVersion: couchbase.com/v1
kind: CouchbaseCluster
metadata:
  name: cb-example
  namespace: mycouchbase
spec:
  authSecret: cb-example-auth
  baseImage: registry.connect.redhat.com/couchbase/server
  buckets:
    - conflictResolution: seqno
      enableFlush: true
      evictionPolicy: fullEviction
      ioPriority: high
      memoryQuota: 128
      name: default
      replicas: 1
      type: couchbase
  cluster:
    analyticsServiceMemoryQuota: 1024
    autoFailoverMaxCount: 3
    autoFailoverOnDataDiskIssues: true
    autoFailoverOnDataDiskIssuesTimePeriod: 120
    autoFailoverServerGroup: false
    autoFailoverTimeout: 120
    clusterName: cb-example
    dataServiceMemoryQuota: 256
    eventingServiceMemoryQuota: 256
    indexServiceMemoryQuota: 256
    indexStorageSetting: memory_optimized
    searchServiceMemoryQuota: 256
  servers:
    - name: all_services
      services:
        - data
        - index
        - query
        - search
        - eventing
        - analytics
      size: 3
  version: 5.5.3-3

The operator provides many sensible defaults. Take note of the servers stanza and its size element. This represents the number of distinct Couchbase Pods that will be created and managed by the operator. We'll explore changing that in a moment.

Click "Create". Afterwards, you will be taken to a list of all Couchbase instances running with this Project and should see the one you just created has a status of "Creating".

View the Deployed Resources

Navigate to the Couchbase Cluster that was deployed by clicking cb-example, and then click on the "Resources" tab. This collects all of the objects deployed and managed by the Operator. From here you can ultimately view Pod logs to check on the Couchbase Cluster instances.

If for some reason you had navigated away from the page after creating your Couchbase cluster, you can get back here by clicking "Catalog" -> "Installed Operators" -> "Couchbase Cluster" -> cb-example.

We are going to use the Service cb-example to access the Couchbase dashboard via a Route:

oc expose service cb-example -n mycouchbase

You should now have a route:

oc get route -n mycouchbase

Which will show something like:

NAME         HOST/PORT                                                                  PATH   SERVICES     PORT        TERMINATION   WILDCARD
cb-example   cb-example-mycouchbase.apps.beta-190304-2.ocp4testing.openshiftdemos.com          cb-example   couchbase                 None

Your Couchbase installation is now exposed directly to the internet and is not using HTTPS. Go ahead and copy/paste the URL into your browser. Login with the user couchbase and the password securepassword (these were in your secret). If you used different credentials, make sure you put in the right ones.

Re-Configure the Cluster with the Operator

Keep the Couchbase dashboard up as we re-configure the cluster. As the Operator scales up more Pods, they will automatically join and appear in the dashboard.

Edit your cb-example Couchbase instance to have a server size of 4 instead of 3. You can navigate back to the installed instances of Couchbase via the web console, or you can use:

oc edit couchbaseclusters.couchbase.com/cb-example -n mycouchbase

A few things will happen:

  • The Operator will detect the difference between the desired state and the current state
  • A new Pod will be created and show up under "Resources"
  • The Couchbase dashboard will show 4 instances once the Pod is created
  • The Couchbase dashboard will show that the cluster is being rebalanced

After the cluster is scaled up to 4, try scaling back down to 3. If you watch the dashboard closely, you will see that Couchbase as automatically triggered a re-balance of the data within the cluster to reflect the new topology of the cluster. This is one of many advanced feautres embedded within applications in OperatorHub to save you time when administering your workloads.

Delete the Couchbase Instance

After you are done, delete the cb-example Couchbase instance and the Opeator will clean up all of the resources that were deployed. Remember to delete the Route that we manually created as well. Remember to delete the Operator instance and not to delete the Pods or other resources directly -- the operator will immediately try to fix that thinking that there's a problem!

After you delete the cb-example instance, if you look at the Project quickly you'll see the Pods terminating:

oc get pod -n mycouchbase

But you'll also see that the Operator Pod remains. That's because there's still a Subscription for the Couchbase operator in this Project. You can delete the Subscription (and, thus, the Pod) by going to "Operator Management" -> "Operator Subscriptions". There you can click the 3 dots and remove the Subscription for the Couchbase Operator in the mycouchbase Project. Now there should be no Pods, and you can also delete the Project if you want.

Try Out More Operators

Operators are a powerful way for cluster administrators to extend the cluster, so that developers can build their apps and services in a self-service way. With the expertise baked into an Operator, running high quality, production instructure has never been easier.

OperatorHub will be continually updated with more great Operators from Red Hat, certified partners and the Kubernetes community.

End of Materials

Congratulations. You have reached the end of the materials. Feel free to explore your cluster further.

If you are done, you can proceed to cleanup your cluster You can also take a look at the tips and tricks section.