Overview of Auto-Scale in App Service

Azure App Service provides a robust and flexible auto-scaling feature that adjusts the amount of computational resources that are allocated to your web app in response to incoming demand. This feature ensures that your application is always equipped with the right amount of resources to handle the current load, minimizing the waste of resources and potentially saving you money.

The primary function of auto-scaling is to automatically scale out based on predefined rules and triggers such as CPU usage, memory consumption. This way, the app service plan automatically adjusts the number of running instances to meet the needs of your application.

Viewing the Scale-Out History from Scale-Out Settings

Azure provides an easy way to view the history of your resources' scale events. From your App Service Plan, you can go to the 'Scale out (App Service Plan)' blade and click on the 'Run history' tab. Here, you'll find a list of scale actions that have been executed, showing when each action took place, and whether it was successful.

View the history of your resource's scale events

This allows you to review how your scaling settings have been performing and make any necessary adjustments to ensure your application continues to perform optimally. It is a valuable tool for understanding the behavior of your application under different load conditions and can help in identifying patterns and making future predictions.

Using Activity Logs to Monitor Auto-Scale Events

Azure Activity Logs provides a wealth of information about operations taken on resources in your Azure subscription. Among these operations, you can find entries for the auto-scaling actions that your App Service Plan has taken. You can filter these logs for specific Operation names such as "Autoscale scale down completed", "Autoscale scale down initiated", "Autoscale scale up completed", and "Autoscale scale up initiated" to see exactly when your App Service Plan has scaled out.

This allows you to clearly understand how much the instances have increased or decreased around the autoscale events in a timeline, providing greater context and aiding in the comprehension and troubleshooting of any issues.

Checking the Change History in details

When you select a specific auto-scale activity in the Activity Log, a panel appears on the right side of the screen showing more details about the event. Among these details, you can find the 'Change history' tab. This tab shows a list of changes that occurred 30 minutes before and after the operation time. This gives you a clear picture of what changes were happening around the time of the auto-scale event, providing more context and aiding in understanding and troubleshooting any issues.

In conclusion, Azure App Service provides the tools and information necessary to not only implement auto-scaling but to also monitor and understand how it's working for your application. By utilizing the 'Run history' and Activity Logs, you can ensure your application is scaling appropriately and troubleshoot any issues that may arise.