allow specification of update strategy on slaves (#9157)

* allow specification of update strategy on slaves

allow specification of update strategy on slaves, you should be able to specify stuff like maxUnavailable on slave updates. Otherwise, all your slaves may restart while the master is terminating/initializing. If this happens your slaves will be down just as long as the master

Signed-off-by: Alec Troemel <alec@mirusresearch.com>

* version bump

Signed-off-by: Alec Troemel <alec@mirusresearch.com>

* update docs

Signed-off-by: Alec Troemel <alec@mirusresearch.com>

* remove trailing spaces

Signed-off-by: Alec Troemel <alec@mirusresearch.com>

* remove extra paren

Signed-off-by: Alec Troemel <alec@mirusresearch.com>

stable/redis/Chart.yaml

@@ -1,5 +1,5 @@
 name: redis
-version: 4.2.8
+version: 4.2.9
 appVersion: 4.0.11
 description: Open source, advanced key-value store. It is often referred to as a data structure server since keys can contain strings, hashes, lists, sets and sorted sets.
 keywords:

stable/redis/templates/redis-slave-deployment.yaml

@@ -9,6 +9,10 @@ metadata:
     release: "{{ .Release.Name }}"
     heritage: "{{ .Release.Service }}"
 spec:
+{{- if .Values.slave.updateStrategy }}
+  strategy:
+{{ toYaml .Values.slave.updateStrategy | indent 4 }}
+{{- end }}
 {{- if .Values.cluster.slaveCount }}
   replicas: {{ .Values.cluster.slaveCount }}
 {{- end }}

stable/redis/values.yaml

@@ -245,6 +245,10 @@ slave:
   # extraFlags: []
   ## Comma-separated list of Redis commands to disable
   # disableCommands: ""
+  ## deployment update stategy
+  # updateStrategy:
+  #   rollingUpdate:
+  #     maxUnavailable: 0
 
   ## Redis Slave pod/node affinity/anti-affinity
   ##