compose: App Service - containerless/runtime-specific support

[JeffreyCA]

Notes

• App Service has Language-specific settings
  • Also see: https://github.com/microsoft/Oryx/tree/main/doc/runtimes
  • Python has a special environment variable for Gunicorn multiple workers support: PYTHON_ENABLE_GUNICORN_MULTIWORKERS=true
• May need to expose a way to configure the startup command: https://azureossd.github.io/2022/02/22/Using-PM2-on-App-Service-Linux/
  • Also see: https://learn.microsoft.com/troubleshoot/azure/app-service/faqs-app-service-linux#what-are-the-expected-values-for-the-startup-file-section-when-i-configure-the-runtime-stack-

App settings/connection strings

From https://learn.microsoft.com/azure/app-service/configure-common?tabs=portal#configure-connection-strings:

For ASP.NET and ASP.NET Core developers, setting connection strings in App Service is like setting them in in Web.config. The values that you set in App Service override the ones in Web.config. You can keep development settings, such as a database file, in Web.config. You can keep production secrets, such as SQL database credentials, safely in App Service. The same code uses your development settings when you debug locally. It uses your production secrets when you deploy it to Azure.

For other language stacks, it's better to use app settings instead. Connection strings require special formatting in the variable keys to access the values.

There's one case where you might want to use connection strings instead of app settings for non-.NET languages. Certain Azure database types are backed up along with the app only if you configure a connection string for the database in your App Service app. For more information, see Create a custom backup. If you don't need this automated backup, use app settings.

May be relevant if configuring connection strings: dotnet/runtime#36123