App Settings - Azure App Service (Multiple environments)

I am trying to set up connectivity from azure app service to azure sql db using managed identity (System assigned)

Here is the set up: Two azure app services one for app and one for api in one service plan. I have a SQL server in Azure with two azure sql db. The app services have their system assigned managed identity turned on. I have app settings for multiple environments in both the project (app and api).

appsettings.json
appsetings.Development.json
appsettings.Acceptance.json
appsettings.Production.json

When I explored Kudu after deploying my app to app service from yaml pipeline I see all the app settings files are available.

The configuration ->application setting in Azure app service just has the app insight instrumentation key which I add (IaC) in template while provisioning app service in Azure. In this situation:

If all the app settings file are pushed (as seen in Kudu), which app setting will be read? appsettings.json or any other environment specific? As I understand it should be appsettings.json. Will the best way to handle the app settings for different environments would be to only have appsettings.json and appsettings.development.json in solution/repo and while provisioning azure app service (IaC template), parameter files for different environments can have the required settings (stored as secrets in key vault and read)? Or any other way is better, easy, and secure? I am not sure how can I make use of secrets manager for multiple environment.

As I have mentioned, reading of App settings will be based on the Environment.

• If we want the Azure App to pick any particular configuration file, then we need to set the key ASPNETCORE_ENVIRONMENT with the specific value (Development/Production/Acceptance).

>When I explored Kudu after deploying my app to app service from yaml pipeline I see all the app settings files are available.

Yes, when we publish the Application, all the available configuration files are deployed to Azure App Service.

You can see the same for my application too.

KUDU Console:

• As you said you are deploying your app service from yaml pipeline, then the configurations which you have specified in the yaml file only will be used.

• Even though you see all the files in the KUDU Console, the configurations which are only specified in the yaml file be used in the App.

• AFAIK, the application setting which are only transformed in the yaml file are only read.

• You can find the option in Azure App Service deploy Task in the Pipeline.

• You can see the configurations of yaml in the Azure App Service => Configuration => Application settings.

Refer MSDoc for more information on XML Transformations.

>csharp
>Will the best way to handle the app settings for different environments would be to only have appsettings.json and appsettings.development.json in solution/repo and while provisioning azure app service (IaC template), parameter files for different environments can have the required settings (stored as secrets in key vault and read)?
>

To Use Azure Key Vault for storing secrets we have an option in Aure Pipeline Task.

Thanks @rahulpnath for the clear explanation on how configuration file works in different environment.