feat: multi-az flag (#130)

Author: levkk

Chart.yaml

@@ -1,4 +1,4 @@
 apiVersion: v1
 name: pgdog
-version: v0.74
-appVersion: "0.1.52"
+version: v0.75
+appVersion: "v0.1.52"

README.md

@@ -160,6 +160,20 @@ podAntiAffinity:
   type: soft # "soft" (preferred) or "hard" (required)
 ```
 
+#### Multi-AZ
+
+Spread replicas evenly across availability zones with a maximum skew of one:
+
+```yaml
+multiAz:
+  enabled: true
+  whenUnsatisfiable: ScheduleAnyway
+```
+
+This uses the `topology.kubernetes.io/zone` node label. Set
+`whenUnsatisfiable` to `DoNotSchedule` to make the constraint strict. Additional
+constraints can be set with `topologySpreadConstraints`.
+
 ### Config Change Restarts
 
 By default, ConfigMap changes are not automatically picked up by

scripts/schema-overrides.yaml

@@ -462,6 +462,12 @@ topologySpreadConstraints:
   description: Topology spread constraints
   items:
     type: object
+multiAz.enabled:
+  type: boolean
+  description: Enable spreading pods evenly across availability zones
+multiAz.whenUnsatisfiable:
+  enum: ["DoNotSchedule", "ScheduleAnyway"]
+  description: Action to take when the zone spread constraint cannot be satisfied
 
 # --- Pod anti-affinity ---
 podAntiAffinity.enabled:

templates/deployment.yaml

@@ -279,9 +279,19 @@ spec:
           {{- end }}
         {{- end }}
       {{- end }}
-      {{- with .Values.topologySpreadConstraints }}
+      {{- if or .Values.multiAz.enabled .Values.topologySpreadConstraints }}
       topologySpreadConstraints:
+        {{- if .Values.multiAz.enabled }}
+        - maxSkew: 1
+          topologyKey: topology.kubernetes.io/zone
+          whenUnsatisfiable: {{ .Values.multiAz.whenUnsatisfiable }}
+          labelSelector:
+            matchLabels:
+              {{- include "pgdog.selectorLabels" . | nindent 14 }}
+        {{- end }}
+        {{- with .Values.topologySpreadConstraints }}
         {{- toYaml . | nindent 8 }}
+        {{- end }}
       {{- end }}
   {{- if and .Values.statefulSet.enabled .Values.statefulSet.walPvc.enabled }}
   volumeClaimTemplates:

test/values-multi-az.yaml

@@ -0,0 +1,4 @@
+# Test multi-AZ topology spread rendering
+multiAz:
+  enabled: true
+  whenUnsatisfiable: DoNotSchedule

values.yaml

@@ -397,6 +397,12 @@ topologySpreadConstraints: []
   #     matchLabels:
   #       app: pgdog
 
+# multiAz spreads pods evenly across availability zones with a maximum skew of 1.
+multiAz:
+  enabled: true
+  # Valid values: DoNotSchedule, ScheduleAnyway
+  whenUnsatisfiable: ScheduleAnyway
+
 # podAntiAffinity enables default anti-affinity rules to spread pods
 # across nodes
 # Set to true for automatic pod anti-affinity configuration