[stable] [nignx-ingress] Add HPA to defaultBackend. Update doc, bump …

…version. (helm#23275)

Signed-off-by: Adam Hamsik <adam.hamsik@lablabs.io>

stable/nginx-ingress/Chart.yaml

@@ -1,6 +1,6 @@
 apiVersion: v1
 name: nginx-ingress
-version: 1.41.1
+version: 1.41.2
 appVersion: v0.34.1
 home: https://github.com/kubernetes/ingress-nginx
 description: An nginx Ingress controller that uses ConfigMap to store the nginx configuration.

stable/nginx-ingress/README.md

@@ -198,6 +198,11 @@ Parameter | Description | Default
 `defaultBackend.extraArgs` | Additional default backend container arguments | `{}`
 `defaultBackend.extraEnvs` | any additional environment variables to set in the defaultBackend pods | `[]`
 `defaultBackend.port` | Http port number | `8080`
+`defaultBackend.autoscaling.enabled` | If true, creates Horizontal Pod Autoscaler | false
+`defaultBackend.autoscaling.minReplicas` | If autoscaling enabled, this field sets minimum replica count | `1`
+`defaultBackend.autoscaling.maxReplicas` | If autoscaling enabled, this field sets maximum replica count | `2`
+`defaultBackend.autoscaling.targetCPUUtilizationPercentage` | Target CPU utilization percentage to scale | "50"
+`defaultBackend.autoscaling.targetMemoryUtilizationPercentage` | Target memory utilization percentage to scale | "50"
 `defaultBackend.livenessProbe.initialDelaySeconds` | Delay before liveness probe is initiated | 30
 `defaultBackend.livenessProbe.periodSeconds` | How often to perform the probe | 10
 `defaultBackend.livenessProbe.timeoutSeconds` | When the probe times out | 5
@@ -411,3 +416,46 @@ Error: UPGRADE FAILED: Service "?????-controller" is invalid: spec.clusterIP: In
 Detail of how and why are in [this issue](https://github.com/helm/charts/pull/13646) but to resolve this you can set `xxxx.service.omitClusterIP` to `true` where `xxxx` is the service referenced in the error.
 
 As of version `1.26.0` of this chart, by simply not providing any clusterIP value, `invalid: spec.clusterIP: Invalid value: "": field is immutable` will no longer occur since `clusterIP: ""` will not be rendered.
+
+## Using custom default backend
+
+Default can be used to server custom error pages when service endpoints are not available. This is requires custom webserver image build with simmilar configuration as below.
+
+```
+server {
+  listen 80 default_server;
+
+  location /nginx_status {
+    stub_status on;
+    access_log  off;
+    allow 127.0.0.1;
+    allow all;
+    deny all;
+  }
+
+  location /healthz {
+    stub_status on;
+    access_log  off;
+    allow 127.0.0.1;
+    allow all;
+    deny all;
+  }
+
+}
+
+###
+# DefaultBackend application handler block
+server {
+  listen 80;
+  server_name *.example-app.com example-app.com;
+
+  access_log  /var/log/nginx/access.log main;
+  root /usr/share/nginx/html;
+
+  location / {
+    add_header Content-Type application/json;
+    add_header Cache-Control "no-cache, no-store" always;
+    try_files /maintenance.json  =502;
+  }
+}
+```

stable/nginx-ingress/templates/default-backend-deployment.yaml

@@ -20,7 +20,9 @@ spec:
     {{- if .Values.defaultBackend.useComponentLabel }}
       {{ .Values.defaultBackend.componentLabelKeyOverride | default "app.kubernetes.io/component" }}: default-backend
     {{- end }}
+{{- if not .Values.defaultBackend.autoscaling.enabled }}
   replicas: {{ .Values.defaultBackend.replicaCount }}
+{{- end }}
   revisionHistoryLimit: {{ .Values.revisionHistoryLimit }}
   template:
     metadata:

stable/nginx-ingress/templates/default-backend-hpa.yaml

@@ -0,0 +1,32 @@
+{{- if .Values.defaultBackend.autoscaling.enabled }}
+apiVersion: autoscaling/v2beta1
+kind: HorizontalPodAutoscaler
+metadata:
+  labels:
+    app: {{ template "nginx-ingress.name" . }}
+    chart: {{ template "nginx-ingress.chart" . }}
+    component: "{{ .Values.defaultBackend.name }}"
+    heritage: {{ .Release.Service }}
+    release: {{ .Release.Name }}
+  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 }}

stable/nginx-ingress/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:

stable/nginx-ingress/values.yaml

@@ -545,6 +545,13 @@ defaultBackend:
   #   cpu: 10m
   #   memory: 20Mi
 
+  autoscaling:
+    enabled: false
+    minReplicas: 1
+    maxReplicas: 2
+    targetCPUUtilizationPercentage: 50
+    targetMemoryUtilizationPercentage: 50
+
   service:
     annotations: {}
     ## Deprecated, instead simply do not provide a clusterIP value