Staging vs Production slot - Azure Web app deployment

Question

My Application has two app service plan. Non Prod and Prod. We are using NonProd for development and testing. And, Prod for Production. However, its found that, the Prod has only one slot(that is, no staging slot present)

I refereed this : https://docs.microsoft.com/en-us/azure/app-service/deploy-staging-slots and recommended the infra to create a staging slot in the Prod app service plan. However, got the answer that are multiple things has to be changed if they are making a staging slot. For example, during swap the stage URL will replace the Production URL and they need to change DNS to map those. - Are DNS change required?

As per my knowledge this should not be the case.

My question is, Is it that, during swap ( due to some different configurations) the production URL will be replaced by the stage URL?? Also, are there any step by step guide, which will clarify and confirm , what all things will change and what all will not? What all team's involvement required considering real customer application going to Prod?

As per my knowledge, the best recommended way is to create a stage and swap, this is not that difficult and should be completed in 5 mins (if proper access is there).

Hope I have explained this correctly. If someone has faced similar situation and has some better past expertise, please clarify. Thanks.

Answer 1

For example, during swap the stage URL will replace the Production URL and they need to change DNS to map those. - Are DNS change required?

No DNS changes are required. The production URL will point to the new version after the swap.

Configuration is one thing you have to check, by default configuration settings will move with the slot. So any settings that you want to keep in a slot, you need to mark as "sticky"/slot-specific.

If you go to the App Service -> Configuration, you can click Edit for a setting:

Then you can check Deployment slot setting if you want the setting to be specific to that slot and not move during swap:

You can see what happens during a swap here: https://docs.microsoft.com/en-us/azure/app-service/deploy-staging-slots#what-happens-during-a-swap.

What settings are swapped: https://docs.microsoft.com/en-us/azure/app-service/deploy-staging-slots#which-settings-are-swapped

Settings that are swapped:

General settings, such as framework version, 32/64-bit, web sockets
App settings (can be configured to stick to a slot)
Connection strings (can be configured to stick to a slot)
Handler mappings
Public certificates
WebJobs content
Hybrid connections *
Virtual network integration *
Service endpoints *
Azure Content Delivery Network *

Features marked with an asterisk (*) are planned to be unswapped.

Settings that aren't swapped:

Publishing endpoints
Custom domain names
Non-public certificates and TLS/SSL settings
Scale settings
WebJobs schedulers
IP restrictions
Always On
Diagnostic settings
Cross-origin resource sharing (CORS)