Allow topologySpreadConstraints configuration (#14684)

The default replica value is 16 (right now) which can lead to massive
resource consumption on one node in smaller clusters. The idea for this
addition is to allow users to specify how the pods (replicas) are being
spread across the cluster. It gives more control over this Helm Release
in smaller clusters where most worker nodes have taints.

As this Kubernetes feature exists since Kubernetes 1.19 and is only
useful for a replica count > 1, this was taken into account.

helm/minio/templates/statefulset.yaml

@@ -1,6 +1,7 @@
 {{- if eq .Values.mode "distributed" }}
 {{ $poolCount := .Values.pools | int }}
 {{ $nodeCount := .Values.replicas | int }}
+{{ $replicas := mul $poolCount $nodeCount }}
 {{ $drivesPerNode := .Values.drivesPerNode | int }}
 {{ $scheme := "http" }}
 {{- if .Values.tls.enabled }}
@@ -57,7 +58,7 @@ spec:
     type: {{ .Values.StatefulSetUpdate.updateStrategy }}
   podManagementPolicy: "Parallel"
   serviceName: {{ template "minio.fullname" . }}-svc
-  replicas: {{ mul $poolCount $nodeCount }}
+  replicas: {{ $replicas }}
   selector:
     matchLabels:
       app: {{ template "minio.name" . }}
@@ -168,6 +169,12 @@ spec:
     {{- with .Values.tolerations }}
       tolerations:
 {{ toYaml . | indent 8 }}
+    {{- end }}
+    {{- if and (gt $replicas 1) (ge .Capabilities.KubeVersion.Major "1") (ge .Capabilities.KubeVersion.Minor "19") }}
+    {{- with .Values.topologySpreadConstraints }}
+      topologySpreadConstraints:
+{{ toYaml . | indent 8 }}
+    {{- end }}
     {{- end }}
       volumes:
         - name: minio-user

helm/minio/values.yaml

@@ -226,6 +226,7 @@ consoleIngress:
 nodeSelector: {}
 tolerations: []
 affinity: {}
+topologySpreadConstraints: []
 
 ## Add stateful containers to have security context, if enabled MinIO will run as this
 ## user and group NOTE: securityContext is only enabled if persistence.enabled=true