README updated to add certmanager installation step (#133)

* README updated to add certmanager installation step

Author: bharathi-tenneti

go/kubebuilder/memcached-operator/README.md

@@ -33,24 +33,44 @@ Run the following command
 ```
 $ go mod tidy
 ```
+***NOTE*** As this example showcases validation webhook creation, please follow [this][certmanager] guide to install cert-mamager into cluster prior to deployment.
 
 ### Building the operator
 
 Build the Memcached operator image and push it to a public registry, such as quay.io:
 
-```
-$ make install
+```shell
 $ export IMG=quay.io/example-inc/memcached-operator:v0.0.1
-$ make docker-build $IMG
-$ docker push $IMG
-$ make deploy $IMG
+$ make docker-build docker-push IMG=$IMG
 ```
 
 **NOTE** The `quay.io/example-inc/memcached-operator:v0.0.1` is an example. You should build and push the image for your repository.
 
+### Instaling Operator API
+
+Install the CRDs into the cluster:
+
+```shell
+$ make install
+```
+### Deploying your operator 
+
+Deploy the Memcached Operator to the cluster with image specified by IMG
+
+```shell
+$ make deploy IMG=$IMG
+```
+
+### Create memcached-sample instances.
+
+```shell
+$ kubectl create -f config/samples/cache_v1alpha1_memcached.yaml -n  memcached-operator-system
+```
+
 Please verify expected result.
 
 ```shell
+
 $ kubectl get all -n memcached-operator-system 
 NAME                                                         READY   STATUS    RESTARTS   AGE
 pod/memcached-operator-controller-manager-864f7c75d4-7cf47   2/2     Running   0          118s
@@ -69,6 +89,16 @@ NAME                                                               DESIRED   CUR
 replicaset.apps/memcached-operator-controller-manager-864f7c75d4   1         1         1       118s
 ```
 
+### Verifying the validating webhook
+
+The following command attempts to increase the CR's `spec.size` to an even number. It should throw an error like that shown below, as the validating webhook does not allow an even `spec.size`.
+
+```console
+$ kubectl patch memcached memcached-sample -p '{"spec":{"size": 4}}' --type=merge -n memcached-operator-system
+
+Error from server (Cluster size must be an odd number): admission webhook "vmemcached.kb.io" denied the request: Cluster size must be an odd number
+```
+
 ### Uninstalling
 
 To uninstall all that was performed in the above step run `make uninstall`.
@@ -89,3 +119,4 @@ $ kubectl logs deployment.apps/memcached-operator-controller-manager -n  memcach
 [operator_sdk]: https://github.com/operator-framework/operator-sdk
 [operator_install]: https://sdk.operatorframework.io/docs/install-operator-sdk/
 [quickstart]: https://github.com/operator-framework/operator-sdk/blob/master/website/content/en/docs/kubebuilder/quickstart.md#implement-the-controller
+[certmanager]: https://cert-manager.io/docs/installation/kubernetes/

go/kubebuilder/memcached-operator/config/manager/kustomization.yaml

@@ -5,3 +5,4 @@ kind: Kustomization
 images:
 - name: controller
   newName: quay.io/example-inc/memcached-operator
+  newTag: v0.0.1