add toggle to disable creation of CRD validation and document it

docs/administrator.md

@@ -3,6 +3,30 @@
 Learn how to configure and manage the Postgres Operator in your Kubernetes (K8s)
 environment.
 
+## CRD Validation
+
+[CustomResourceDefinitions](https://kubernetes.io/docs/concepts/extend-kubernetes/api-extension/custom-resources/#customresourcedefinitions)
+will be registered with schema validation by default when the operator is
+deployed. The `OperatorConfiguration` CRD will only get created if the
+`POSTGRES_OPERATOR_CONFIGURATION_OBJECT` [environment variable](../manifests/postgres-operator.yaml#L36)
+in the deployment yaml is set and not empty.
+
+When submitting manifests of [`postgresql`](../manifests/postgresql.crd.yaml) or
+[`OperatorConfiguration`](../manifests/operatorconfiguration.crd.yaml) custom
+resources with kubectl, validation can be bypassed with `--validate=false`. The
+operator can also be configured to not register CRDs with validation on `ADD` or
+`UPDATE` events. Running instances are not affected when enabling the validation
+afterwards unless the manifests is not changed then. Note, that the provided CRD
+manifests contain the validation for users to understand what schema is
+enforced.
+
+Once the validation is enabled it can only be disabled manually by editing or
+patching the CRD manifest:
+
+```bash
+zk8 patch crd postgresqls.acid.zalan.do -p '{"spec":{"validation": null}}'
+```
+
 ## Namespaces
 
 ### Select the namespace to deploy to

docs/quickstart.md

@@ -119,15 +119,15 @@ kubectl get pod -l app.kubernetes.io/name=postgres-operator
 kubectl create -f manifests/minimal-postgres-manifest.yaml
 ```
 
-After the cluster manifest is submitted the operator will create Service and
-Endpoint resources and a StatefulSet which spins up new Pod(s) given the number
-of instances specified in the manifest. All resources are named like the
-cluster. The database pods can be identified by their number suffix, starting
-from `-0`. They run the [Spilo](https://github.com/zalando/spilo) container
-image by Zalando. As for the services and endpoints, there will be one for the
-master pod and another one for all the replicas (`-repl` suffix). Check if all
-components are coming up. Use the label `application=spilo` to filter and list
-the label `spilo-role` to see who is currently the master.
+After the cluster manifest is submitted and passed the validation the operator
+will create Service and Endpoint resources and a StatefulSet which spins up new
+Pod(s) given the number of instances specified in the manifest. All resources
+are named like the cluster. The database pods can be identified by their number
+suffix, starting from `-0`. They run the [Spilo](https://github.com/zalando/spilo)
+container image by Zalando. As for the services and endpoints, there will be one
+for the master pod and another one for all the replicas (`-repl` suffix). Check
+if all components are coming up. Use the label `application=spilo` to filter and
+list the label `spilo-role` to see who is currently the master.
 
 ```bash
 # check the deployed cluster

docs/reference/operator_parameters.md

@@ -69,6 +69,11 @@ Variable names are underscore-separated words.
 
 Those are top-level keys, containing both leaf keys and groups.
 
+* **enable_crd_validation**
+  toggles if the operator will create or update CRDs with
+  [OpenAPI v3 schema validation](https://kubernetes.io/docs/tasks/access-kubernetes-api/custom-resources/custom-resource-definitions/#validation)
+  The default is `true`.
+
 * **etcd_host**
   Etcd connection string for Patroni defined as `host:port`. Not required when
   Patroni native Kubernetes support is used. The default is empty (use