APPS-7813 Add autoscaling section to apps (#849)

Co-authored-by: Andrew Starr-Bochicchio <andrewsomething@users.noreply.github.com>

specification/resources/apps/models/app_component_instance_base.yml

@@ -5,7 +5,7 @@ properties:
     type: integer
     format: int64
     minimum: 1
-    description: 'The amount of instances that this component should be scaled to. Default: 1'
+    description: 'The amount of instances that this component should be scaled to. Default: 1. Must not be set if autoscaling is used.'
     default: 1
     example: 2
 
@@ -25,3 +25,36 @@ properties:
     - professional-xl
     default: basic-xxs
     example: basic-xxs
+
+  autoscaling:
+    description: Configuration for automatically scaling this component based on metrics.
+    type: object
+    properties:
+      min_instance_count:
+        description: The minimum amount of instances for this component. Must be less than max_instance_count.
+        type: integer
+        format: uint32
+        minimum: 1
+        example: 2
+      max_instance_count:
+        description: The maximum amount of instances for this component. Must be more than min_instance_count.
+        type: integer
+        format: uint32
+        minimum: 1
+        example: 3
+      metrics:
+        description: The metrics that the component is scaled on.
+        type: object
+        properties:
+          cpu:
+            description: Settings for scaling the component based on CPU utilization.
+            type: object
+            properties:
+              percent:
+                description: The average target CPU utilization for the component.
+                type: integer
+                format: uint32
+                minimum: 1
+                maximum: 100
+                default: 80
+                example: 75