feat: add option in chart to add hpa to gateway

re envoyproxy#703

Signed-off-by: Gazal Gafoor <gazal.gafoor@rea-group.com>

charts/gateway-helm/templates/envoy-gateway-deployment.yaml

@@ -15,7 +15,9 @@ metadata:
     control-plane: envoy-gateway
   {{- include "eg.labels" . | nindent 4 }}
 spec:
+  {{- if not .Values.autoscaling.enabled }}
   replicas: {{ .Values.deployment.replicas }}
+  {{- end }}
   selector:
     matchLabels:
       control-plane: envoy-gateway

charts/gateway-helm/templates/envoy-gateway-hpa.yaml

@@ -0,0 +1,44 @@
+{{- if .Values.autoscaling.enabled -}}
+apiVersion: {{ ternary "autoscaling/v2" "autoscaling/v2beta2" (.Capabilities.APIVersions.Has "autoscaling/v2") }}
+kind: HorizontalPodAutoscaler
+metadata:
+  {{- with .Values.autoscaling.annotations }}
+  annotations: {{ toYaml . | nindent 4 }}
+  {{- end }}
+  labels:
+    control-plane: envoy-gateway
+  {{- include "eg.labels" . | nindent 4 }}
+  name: envoy-gateway
+  namespace: '{{ .Release.Namespace }}'
+spec:
+  scaleTargetRef:
+    apiVersion: apps/v1
+    kind: Deployment
+    name: envoy-gateway
+  minReplicas: {{ .Values.autoscaling.minReplicas }}
+  maxReplicas: {{ .Values.autoscaling.maxReplicas }}
+  metrics:
+  {{- with .Values.autoscaling.targetMemoryUtilizationPercentage }}
+  - type: Resource
+    resource:
+      name: memory
+      target:
+        type: Utilization
+        averageUtilization: {{ . }}
+  {{- end }}
+  {{- with .Values.autoscaling.targetCPUUtilizationPercentage }}
+  - type: Resource
+    resource:
+      name: cpu
+      target:
+        type: Utilization
+        averageUtilization: {{ . }}
+  {{- end }}
+  {{- with .Values.autoscalingTemplate }}
+  {{- toYaml . | nindent 2 }}
+  {{- end }}
+  {{- with .Values.autoscaling.behavior }}
+  behavior:
+    {{- toYaml . | nindent 4 }}
+  {{- end }}
+{{- end }}

charts/gateway-helm/values.tmpl.yaml

@@ -23,6 +23,14 @@ deployment:
     annotations: {}
     labels: {}
 
+autoscaling:
+  enabled: false
+  annotations: {}
+  minReplicas: 1
+  maxReplicas: 10
+  targetCPUUtilizationPercentage: 60
+  targetMemoryUtilizationPercentage: 60
+
 config:
   envoyGateway:
     gateway: