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Oracle WebLogic Operator Tutorial

Scaling WebLogic cluster

WebLogic Server supports two types of clustering configurations, configured and dynamic. Configured clusters are created by manually configuring each individual Managed Server instance. In dynamic clusters, the Managed Server configurations are generated from a single, shared template. With dynamic clusters, when additional server capacity is needed, new server instances can be added to the cluster without having to manually configure them individually. Also, unlike configured clusters, scaling up of dynamic clusters is not restricted to the set of servers defined in the cluster but can be increased based on runtime demands.

The operator provides several ways to initiate scaling of WebLogic clusters, including:

  • On-demand, updating the domain resource directly (using kubectl).
  • Calling the operator's REST scale API, for example, from curl.
  • Using a WLDF policy rule and script action to call the operator's REST scale API.
  • Using a Prometheus alert action to call the operator's REST scale API.

Scaling WebLogic cluster using kubectl

The easiest way to scale a WebLogic cluster in Kubernetes is to simply edit the replicas property within a domain resource. To retain changes edit the domain.yaml and apply changes using kubectl. Use your favourite editor to open domain.yaml.

Find the following part:

clusters:
- clusterName: cluster-1
  serverStartState: "RUNNING"
  replicas: 2

Modify replicas to 3 and save changes. Apply the changes using kubectl:

kubectl apply -f /u01/domain.yaml

Check the changes in the number of pods using kubectl:

kubectl get po -n sample-domain1-ns
NAME                             READY     STATUS        RESTARTS   AGE
sample-domain1-admin-server      1/1       Running       0          57m
sample-domain1-managed-server1   1/1       Running       0          56m
sample-domain1-managed-server2   1/1       Running       0          55m
sample-domain1-managed-server3   1/1       Running       0          1m

Soon the managed server 3 will appear and will be ready within a few minutes. You can also check the managed server scaling action using the WebLogic Administration console:

alt text

Note! You can edit directly the existing (running) domain resource file by using the kubectl edit command. In this case your domain.yaml available on your desktop will not reflect the changes of the running domain's resource.

kubectl edit domain DOMAIN_UID -n DOMAIN_NAMESPACE

In case if you use default settings the syntax is:

kubectl edit domain sample-domain1 -n sample-domain1-ns

It will use vi like editor.


Note! Do not use the console to scale the cluster. The operator controls this operation. Use the operator's options to scale your cluster deployed on Kubernetes.


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