What is the recommended backup plan to be followed when an Azure App Service is down..?

Sai Charan Uppari 1 Reputation point
2021-06-30T02:28:34.87+00:00

Assumption:
I have an Azure App Service with a standard/premium App Service Plan for my production deployments and it is working fine without any issues. Consider it to be a normal web app or a web app with a container or both.

Situation:
Unfortunately, one day, if the app service is down for some reason (the team will start investigating the issue) what should be the backup plan to minimize the downtime till the root cause is identified and a fix is applied to make the app service up and running...?

Known Approach:
We can have a deployment slot created (already created as backup) for the above app service and if something goes wrong with the main app then we can immediately start the deployment slot and divert the traffic to the slot from the main till the main slot is given a fix.

Question:
Is there any other approach to follow (or being followed across) when an Azure App Service is down for any reason to minimize the downtime, till it is given a fix, made up and running...?

Thanks in Advance.. 😊

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  1. Andriy Bilous 10,896 Reputation points MVP
    2021-07-01T19:21:29.987+00:00

    Hello @Sai Charan Uppari

    First you need to create a Disaster Recovery Plan for your WebApp
    The plan is considered complete after it has been fully tested. Include the people, processes, and applications needed to restore functionality within the service-level agreement (SLA) you've defined for your customers.

    At a high level of backup strategy, the approaches can be divided into the following categories:

    • Redeploy on disaster: In this approach, the application is redeployed from scratch at the time of disaster. This is appropriate for non-critical applications that don’t require a guaranteed recovery time.
    • Warm Spare (Active/Passive): A secondary hosted service is created in an alternate region, and roles are deployed to guarantee minimal capacity; however, the roles don’t receive production traffic. This approach is useful for applications that have not been designed to distribute traffic across regions.
    • Hot Spare (Active/Active): The application is designed to receive production load in multiple regions. The cloud services in each region might be configured for higher capacity than required for disaster recovery purposes. Alternatively, the cloud services might scale-out as necessary at the time of a disaster and failover. This approach requires substantial investment in application design, but it has significant benefits. These include low and guaranteed recovery time, continuous testing of all recovery locations, and efficient usage of capacity.
      https://learn.microsoft.com/en-us/azure/architecture/framework/resiliency/backup-and-recovery

    Redeploy on disaster helps to bring App Service resources back online in a different Azure region during a disaster that impacts an entire Azure region.
    https://learn.microsoft.com/en-us/azure/app-service/manage-disaster-recovery

    Hot Spare or Warm Spare (Highly available) multi-region web application can implement Azure App Service application in multiple regions to achieve high availability.
    https://learn.microsoft.com/en-us/azure/architecture/reference-architectures/app-service-web-app/multi-region

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