PaaS – Scaling out and in

Scaling out and in services hosted in app services is also quite simple. The Azure app services menu items to scale out, which opens a new blade with scaling configuration options.

By default, auto scaling is disabled for both premium and standard plans. It can be enabled using the Scale Out menu item and by clicking on the Enable autoscale button, as shown:

Manual scaling does not require configuration but auto scaling helps in configuring with the aid of the following properties:

• Mode of scaling: Based on some metric, such as CPU or memory usage or just scale to specify the number of instances.
• When to scale: Multiple rules can be added that determine when to scale out and in. Each rule can determine the criteria such as CPU or memory consumption, whether to increase or decrease instances, and how many instances to increase or decrease at a time. At least one rule for scale out and one rule for scale in should be configured. Threshold definitions help in defining the upper and lower limits that should trigger the auto scale—either increase or decrease the number of instances.

• How to scale: Specifies how many instances to create or remove in each scale out or in operation:

This is a quite to good feature to enable in any deployment. However readers should enable both scaling out and in together to ensure that the environment is back to normal capacity after scaling out.