How and where to define an environment variable on Azure

Question

I have an ASP.NET MVC web application deployed to Azure. I\'m reading my setting using the GetEnvironmentVariable(...) method.

The problem is that I can

Answer 1

I know OP specified in the portal, but command line is more repeatable. To do it using Azure CLI:

az webapp config appsettings set -n $webappname -g $resourceGroupName --settings ConnectionStrings__Default=$connectionString

To set an environment variable ConnectionStrings__Default to the variable $connectionString