Add autoscaler for applications (#525)

- Transition to min/max instances instead of total instances

lib/aws/charts/q-application/templates/deployment.j2.yaml

@@ -13,10 +13,10 @@ metadata:
   annotations:
     releaseTime: {% raw %}{{ dateInZone "2006-01-02 15:04:05Z" (now) "UTC"| quote }}{% endraw %}
 spec:
-  replicas: {{ total_instances }}
+  replicas: {{ min_instances }}
   strategy:
     type: RollingUpdate
-    {% if total_instances == 1 %}
+    {% if max_instances == 1 %}
     rollingUpdate:
       maxSurge: 1
     {% endif %}

lib/aws/charts/q-application/templates/horizontal_autoscaler.j2.yaml

@@ -0,0 +1,19 @@
+{%- if not is_storage and min_instances != max_instances %}
+apiVersion: autoscaling/v1
+kind: HorizontalPodAutoscaler
+metadata:
+  name: {{ sanitized_name }}
+  namespace: {{ namespace }}
+  labels:
+    envId: {{ environment_id }}
+    appId: {{ id }}
+spec:
+  scaleTargetRef:
+    apiVersion: apps/v1
+    kind: Deployment
+    name: {{ sanitized_name }}
+  minReplicas: {{ min_instances }}
+  maxReplicas: {{ max_instances }}
+  targetCPUUtilizationPercentage: 60
+{%- endif %}
+

lib/aws/charts/q-application/templates/statefulset.j2.yaml

@@ -13,7 +13,7 @@ metadata:
   annotations:
     releaseTime: {% raw %}{{ dateInZone "2006-01-02 15:04:05Z" (now) "UTC"| quote }}{% endraw %}
 spec:
-  replicas: {{ total_instances }}
+  replicas: {{ min_instances }}
   serviceName: {{ sanitized_name }}
   selector:
     matchLabels: