Hello @Mayank Jain ,
Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.
I understand that you would like to know if it is possible to use Traffic manager and Application gateway instead of Front door for disaster recovery in Azure App services.
Yes, it is possible to use Traffic manager and Application gateway for disaster recovery in Azure App services, which are deployed in multiple regions.
You can configure your Application gateway with app services following the below tutorial:
And then create Traffic Manager which uses DNS-based routing to load balance incoming traffic across the two regions. Traffic Manager resolves DNS queries for the application to the public IP addresses of the Application Gateway endpoints. The public endpoints of the Application gateways serve as the backend endpoints of Traffic Manager. Traffic Manager resolves DNS queries based on a choice of six routing methods.
Traffic manager provides automatic failover if there's a regional outage. It uses priority routing and regular health checks to determine where to route traffic.
In Priority traffic-routing method, by default, Traffic Manager sends all traffic to the primary (highest-priority) endpoint. If the primary endpoint isn't available, Traffic Manager routes the traffic to the second endpoint.
Refer: https://zcusa.951200.xyz/en-us/azure/traffic-manager/traffic-manager-routing-methods
For this setup, you need 2 Application gateways in 2 different regions and then add the backend App services for those regions. At the front, Traffic Manager will load balance incoming traffic across the two regions and send the traffic to the public IP addresses of the Application Gateway endpoints according to the routing method configured.
The Application Gateways receive HTTP(S) traffic from the browser and load balance requests across the backend pool of App services.
Kindly let us know if the above helps or you need further assistance on this issue.
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