feat(cnpg): Adding topologySpreadConstraints support to the deployment

This adds support for specifying
[`topologySpreadConstraints`](https://kubernetes.io/docs/concepts/scheduling-eviction/topology-spread-constraints/)
for the cloudnative-pg operator deployment.

Resolves cloudnative-pg#371

charts/cloudnative-pg/README.md

@@ -73,5 +73,6 @@ CloudNativePG Operator Helm Chart
 | serviceAccount.create | bool | `true` | Specifies whether the service account should be created. |
 | serviceAccount.name | string | `""` | The name of the service account to use. If not set and create is true, a name is generated using the fullname template. |
 | tolerations | list | `[]` | Tolerations for the operator to be installed. |
+| topologySpreadConstraints | list | `[]` | [Topology Spread Constraints](https://kubernetes.io/docs/concepts/scheduling-eviction/topology-spread-constraints/) for the operator to be installed. |
 | webhook | object | `{"livenessProbe":{"initialDelaySeconds":3},"mutating":{"create":true,"failurePolicy":"Fail"},"port":9443,"readinessProbe":{"initialDelaySeconds":3},"validating":{"create":true,"failurePolicy":"Fail"}}` | The webhook configuration. |
 

charts/cloudnative-pg/templates/deployment.yaml

@@ -127,6 +127,10 @@ spec:
       nodeSelector:
         {{- toYaml . | nindent 8 }}
       {{- end }}
+      {{- with .Values.topologySpreadConstraints }}
+      topologySpreadConstraints:
+        {{- toYaml . | nindent 8 }}
+      {{- end }}
       {{- with .Values.affinity }}
       affinity:
         {{- toYaml . | nindent 8 }}

charts/cloudnative-pg/values.schema.json

@@ -11,6 +11,9 @@
         "affinity": {
             "type": "object"
         },
+        "topologySpreadConstraints": {
+            "type": "array"
+        },
         "commonAnnotations": {
             "type": "object"
         },

charts/cloudnative-pg/values.yaml

@@ -141,6 +141,9 @@ resources: {}
 # -- Nodeselector for the operator to be installed.
 nodeSelector: {}
 
+# -- Topology Spread Constraints for the operator to be installed.
+topologySpreadConstraints: []
+
 # -- Tolerations for the operator to be installed.
 tolerations: []