From ab9ba3e970138c39a8b2d2a9fb23f5519a9e2941 Mon Sep 17 00:00:00 2001
From: Adam Hamsik <adam.hamsik@lablabs.io>
Date: Wed, 4 Nov 2020 14:03:50 +0100
Subject: [PATCH] Add Default backend HPA autoscaling.

---
 charts/ingress-nginx/CHANGELOG.md             |  3 ++
 charts/ingress-nginx/Chart.yaml               |  8 ++---
 .../templates/default-backend-deployment.yaml |  2 ++
 .../templates/default-backend-hpa.yaml        | 29 +++++++++++++++++++
 .../default-backend-poddisruptionbudget.yaml  |  2 +-
 charts/ingress-nginx/values.yaml              |  7 +++++
 6 files changed, 44 insertions(+), 7 deletions(-)
 create mode 100644 charts/ingress-nginx/templates/default-backend-hpa.yaml

diff --git a/charts/ingress-nginx/CHANGELOG.md b/charts/ingress-nginx/CHANGELOG.md
index 04ebf157c2..8032f5b87c 100644
--- a/charts/ingress-nginx/CHANGELOG.md
+++ b/charts/ingress-nginx/CHANGELOG.md
@@ -4,6 +4,9 @@ This file documents all notable changes to [ingress-nginx](https://github.com/ku
 
 ### Unreleased
 
+### 3.9.0
+
+- [X] [#6423](https://github.com/kubernetes/ingress-nginx/pull/6423) Add Default backend HPA autoscaling
 
 ### 3.8.0
 
diff --git a/charts/ingress-nginx/Chart.yaml b/charts/ingress-nginx/Chart.yaml
index 1f2a2d58fa..9519bf26d2 100644
--- a/charts/ingress-nginx/Chart.yaml
+++ b/charts/ingress-nginx/Chart.yaml
@@ -1,6 +1,6 @@
 apiVersion: v1
 name: ingress-nginx
-version: 3.8.0
+version: 3.9.0
 appVersion: 0.41.0
 home: https://github.com/kubernetes/ingress-nginx
 description: Ingress controller for Kubernetes using NGINX as a reverse proxy and load balancer
@@ -16,8 +16,4 @@ engine: gotpl
 kubeVersion: ">=1.16.0-0"
 annotations:
   artifacthub.io/changes: |
-    - Update jettech/kube-webhook-certgen image
-    - Added loadBalancerSourceRanges for internal lbs
-    - Add securitycontext settings on defaultbackend
-    - Fix controller service annotations
-    - Initial helm chart changelog
+    - Add Default backend HPA autoscaling
diff --git a/charts/ingress-nginx/templates/default-backend-deployment.yaml b/charts/ingress-nginx/templates/default-backend-deployment.yaml
index 9599c23ac2..0baec8b46a 100644
--- a/charts/ingress-nginx/templates/default-backend-deployment.yaml
+++ b/charts/ingress-nginx/templates/default-backend-deployment.yaml
@@ -11,7 +11,9 @@ spec:
     matchLabels:
       {{- include "ingress-nginx.selectorLabels" . | nindent 6 }}
       app.kubernetes.io/component: default-backend
+{{- if not .Values.defaultBackend.autoscaling.enabled }}
   replicas: {{ .Values.defaultBackend.replicaCount }}
+{{- end }}
   revisionHistoryLimit: {{ .Values.revisionHistoryLimit }}
   template:
     metadata:
diff --git a/charts/ingress-nginx/templates/default-backend-hpa.yaml b/charts/ingress-nginx/templates/default-backend-hpa.yaml
new file mode 100644
index 0000000000..7f345ce9cd
--- /dev/null
+++ b/charts/ingress-nginx/templates/default-backend-hpa.yaml
@@ -0,0 +1,29 @@
+{{- if .Values.defaultBackend.autoscaling.enabled }}
+apiVersion: autoscaling/v2beta1
+kind: HorizontalPodAutoscaler
+metadata:
+  labels:
+    {{- include "ingress-nginx.labels" . | nindent 4 }}
+    app.kubernetes.io/component: default-backend
+  name: {{ template "nginx-ingress.defaultBackend.fullname" . }}
+spec:
+  scaleTargetRef:
+    apiVersion: {{ template "deployment.apiVersion" . }}
+    kind: Deployment
+    name: {{ template "nginx-ingress.defaultBackend.fullname" . }}
+  minReplicas: {{ .Values.defaultBackend.autoscaling.minReplicas }}
+  maxReplicas: {{ .Values.defaultBackend.autoscaling.maxReplicas }}
+  metrics:
+{{- with .Values.defaultBackend.autoscaling.targetCPUUtilizationPercentage }}
+    - type: Resource
+      resource:
+        name: cpu
+        targetAverageUtilization: {{ . }}
+{{- end }}
+{{- with .Values.defaultBackend.autoscaling.targetMemoryUtilizationPercentage }}
+    - type: Resource
+      resource:
+        name: memory
+        targetAverageUtilization: {{ . }}
+{{- end }}
+{{- end }}
diff --git a/charts/ingress-nginx/templates/default-backend-poddisruptionbudget.yaml b/charts/ingress-nginx/templates/default-backend-poddisruptionbudget.yaml
index b6c9c4499a..327d809b95 100644
--- a/charts/ingress-nginx/templates/default-backend-poddisruptionbudget.yaml
+++ b/charts/ingress-nginx/templates/default-backend-poddisruptionbudget.yaml
@@ -1,4 +1,4 @@
-{{- if gt (.Values.defaultBackend.replicaCount | int) 1 -}}
+{{- if or (gt (.Values.defaultBackend.replicaCount | int) 1) (gt (.Values.defaultBackend.autoscaling.minReplicas | int) 1) }}
 apiVersion: policy/v1beta1
 kind: PodDisruptionBudget
 metadata:
diff --git a/charts/ingress-nginx/values.yaml b/charts/ingress-nginx/values.yaml
index 1f3e5783f5..b1b5b4fd11 100644
--- a/charts/ingress-nginx/values.yaml
+++ b/charts/ingress-nginx/values.yaml
@@ -627,6 +627,13 @@ defaultBackend:
   #   cpu: 10m
   #   memory: 20Mi
 
+  autoscaling:
+    enabled: false
+    minReplicas: 1
+    maxReplicas: 2
+    targetCPUUtilizationPercentage: 50
+    targetMemoryUtilizationPercentage: 50
+
   service:
     annotations: {}