Autoscale vmss instance in azure application gateway on the basis of increasing concurrent session.

irshad 

To configure autoscaling of VMSS instances based on increasing concurrent sessions behind Azure Application Gateway, you can follow these steps:

1. Create a VMSS with a minimum and maximum number of instances that you want to scale between. Ensure that the VMSS is configured with the appropriate size and image that you require.
2. Configure the autoscale settings for the VMSS. In the Azure portal, navigate to the VMSS and select "Autoscale" from the left-hand menu. Create a new autoscale setting with a scaling rule based on the number of concurrent sessions. For example, you can set a rule to increase the number of instances when the number of concurrent sessions exceeds a certain threshold, and to decrease the number of instances when the number of concurrent sessions falls below a certain threshold.
3. Configure the Azure Application Gateway to use the VMSS as its backend pool. In the Azure portal, navigate to the Application Gateway and select "Backend pools" from the left-hand menu. Add the VMSS as a backend pool and specify the appropriate health probe and port settings.
4. Configure the Azure Application Gateway to use the autoscale settings for the VMSS. In the Azure portal, navigate to the Application Gateway and select "Autoscaling" from the left-hand menu. Choose the VMSS autoscale setting that you created earlier.

Once you have completed these steps, the VMSS will automatically scale up and down based on the number of concurrent sessions being served by the Azure Application Gateway. This will help to ensure that your website remains responsive and available even during periods of high traffic.

Please mark this thread as closed if this helps 🙂

Reference only: https://learn.microsoft.com/en-us/azure/architecture/best-practices/auto-scaling