feat(helm): add HPA extra metrics

helm/cosmo/charts/router/README.md

@@ -13,6 +13,7 @@ This is the official Helm Chart for the WunderGraph Cosmo Router.
 | affinity | object | `{}` |  |
 | autoscaling.behavior | object | `{}` |  |
 | autoscaling.enabled | bool | `false` |  |
+| autoscaling.extraMetrics | list | `[]` |  |
 | autoscaling.maxReplicas | int | `100` |  |
 | autoscaling.minReplicas | int | `1` |  |
 | autoscaling.targetCPUUtilizationPercentage | int | `80` |  |

helm/cosmo/charts/router/templates/hpa.yaml

@@ -29,6 +29,9 @@ spec:
           type: Utilization
           averageUtilization: {{ .Values.autoscaling.targetMemoryUtilizationPercentage }}
     {{- end }}
+    {{- with .Values.autoscaling.extraMetrics }}
+    {{- toYaml . | nindent 4 }}
+    {{- end }}
   {{- with .Values.autoscaling.behavior }}
   behavior:
     {{- toYaml . | nindent 4 }}

helm/cosmo/charts/router/values.yaml

@@ -143,6 +143,18 @@ autoscaling:
   maxReplicas: 100
   targetCPUUtilizationPercentage: 80
   # targetMemoryUtilizationPercentage: 80
+  extraMetrics: []
+    # Additional HPA metrics appended to the rendered HPA's `metrics:` list.
+    # Each entry must be a full `autoscaling/v2` metric object.
+    # Useful for scaling on metrics provided by an external metrics adapter on top of CPU/memory.
+    # Example of using an external metric:
+    # - type: External
+    #   external:
+    #     metric:
+    #       name: router.http.requests.in_flight
+    #     target:
+    #       type: AverageValue
+    #       averageValue: "50"
   behavior: {}
     # Configures the HPA scaling behavior. When unset, Kubernetes applies its defaults
     # (300s scale-down stabilization window, no scale-up window).