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.
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 mycouchbaseor create it from the web console.
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.
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.
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.
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 couchYou will likely see the Couchbase operator pod in ContainerCreating status
if you look very soon after finishing the installation/subscription process.
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.
-
You can create a key/value secret with a
usernameandpasswordkey in the OpenShift web console by navigating to "Workloads" and then "Secrets". Make sure the Project selector is set tomycouchbase. Finally, you can click "Create" and choose "Key/Value Secret". -
You can make sure the Project selector is set to
mycouchbaseand 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
-
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).
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.
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: 5.5.3-3The 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".
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 mycouchbaseYou should now have a route:
oc get route -n mycouchbaseWhich 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.
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 mycouchbaseA 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.
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 mycouchbaseBut 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.
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.
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.