feat: adding HPA capabilities check (#364)

* Adding HPA capabilities check

Signed-off-by: Ryan Bueter <magnus010@bueters.com>

* Bumping version and adding change

Signed-off-by: Ryan Bueter <magnus010@bueters.com>

---------

Signed-off-by: Ryan Bueter <magnus010@bueters.com>

Author: Magnus010

helm/oauth2-proxy/Chart.yaml

@@ -1,5 +1,5 @@
 name: oauth2-proxy
-version: 8.3.1
+version: 8.3.2
 apiVersion: v2
 appVersion: 7.12.0
 home: https://oauth2-proxy.github.io/oauth2-proxy/
@@ -32,7 +32,7 @@ kubeVersion: ">=1.16.0-0"
 annotations:
   artifacthub.io/changes: |
     - kind: added
-      description: Bump Redis Chart Version
+      description: Adds backwards compatibility with Kubernetes 1.20 by selecting the HPA apiVersion of autoscaling/v2beta2
       links:
         - name: Github PR
-          url: https://github.com/oauth2-proxy/manifests/pull/361
+          url: https://github.com/oauth2-proxy/manifests/pull/364

helm/oauth2-proxy/templates/_capabilities.tpl

@@ -21,3 +21,14 @@ Return the appropriate apiVersion for ingress object.
 {{- print "networking.k8s.io/v1" -}}
 {{- end -}}
 {{- end -}}
+
+{{/*
+Return the appropriate apiVersion for HorizontalPodAutoscaler object.
+*/}}
+{{- define "capabilities.horizontalPodAutoscaler.apiVersion" -}}
+{{- if semverCompare "<1.23-0" ( .Values.kubeVersion | default .Capabilities.KubeVersion.Version ) -}}
+{{- print "autoscaling/v2beta2" -}}
+{{- else -}}
+{{- print "autoscaling/v2" -}}
+{{- end -}}
+{{- end -}}

helm/oauth2-proxy/templates/hpa.yaml

@@ -1,5 +1,5 @@
 {{- if .Values.autoscaling.enabled }}
-apiVersion: autoscaling/v2
+apiVersion: {{ include "capabilities.horizontalPodAutoscaler.apiVersion" . }}
 kind: HorizontalPodAutoscaler
 metadata:
   labels: