App Service Deployment with Zero Downtime

Question

I have a application deployed in Azure App Service. The problem that I am facing now is, how to perform deployment with zero downtime?

I am going to enable the zone redundancy feature onto my App Service, is this feature support the zero downtime by nature? since my application will have at least 3 instances running. Will azure automatically bring down the 1 instance and deploy the latest app, while ensure the other 2 instances are running?

If this zone redundancy doesn't support the zero downtime deployment, then please guide me to the correct direction.

Thanks.

Answer 1

John Wong Yek Hon, To perform a deployment with zero downtime, you may leverage the deployment slots feature in Azure App Service. Deployment slots allow you to deploy a new version of your application to a separate slot, test it, and then swap it with the production slot without any downtime.

Regarding your question about zone redundancy, while zone redundancy can help improve the resiliency and reliability of your application, it does not guarantee zero downtime during deployments.

You may configure auto swap for your deployment slots. This feature automatically swaps the staging slot with the production slot after a successful deployment, ensuring minimal manual intervention and reducing the risk of downtime.

You may apply the approach on accomplishing zero downtime deployments facilitated by a combination of Health checks and deployment slots. Ref: You may checkout this article authored by one of my colleague: Azure App Service, Health checks and zero downtime deployments

Just to highlight:

• Deployment slots are available in Standard, Premium, or Isolated App Service Plan (ASP) tier - Each ASP tier supports a different number of deployment slots. There's no extra charge for using deployment slots.
• Basic tier or higher can scale out to two or more instances and get the full benefit of Health check (feature).

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