Load Connection String from Config File in Azure Functions

// C# Environment Variables example for Azure Functions v1 or v2 runtime
// This works all the way up to but not including .NET Core 2.0
var clientId = Environment.GetEnvironmentVariable("ClientId");
var clientSecret = Environment.GetEnvironmentVariable("ClientSecret");
var aadDomain = Environment.GetEnvironmentVariable("AADDomain");

Please do remember the settings you do in local.settings.json will not be reflected in azure. Please add your values in app setting from Azure portal follow the link- https://docs.microsoft.com/en-us/azure/azure-functions/functions-how-to-use-azure-function-app-settings

I had this same issue and am using .net standard (as opposed to core). I added my settings to the Application Settings section of my Azure function (in Azure Portal):-

I then downloaded a zip of the function:-

Included in this download is a copy of local.settings.json that includes my app settings in the correct json format. I then access them via ConfigurationManager.Appsettings["mysetting"]

Add file local.setting.json

  {
    {
      "IsEncrypted": false,
       "Values": {
      "AzureWebJobsStorage": "UseDevelopmentStorage=true",
      "AzureWebJobsDashboard": "UseDevelopmentStorage=true",

      "tenantId": "You tenantId",
      "resource": "https://management.azure.com/",
      "ClientSecret": "You ClientSecret, Key from App Registry",
      "ClientId": "You ClientId, Application ID from App registry",

      "subscriptionId": "You subscriptionId",
      "resourceGroupName": "Your resourceGroupName",
      "serverName": " Your SQL Server",
      "databaseNameDW": "Your Database",
      "apiversion": "2017-10-01-preview"      
    }
}

In C# Code use:

private readonly static string tenantId = ConfigurationManager.AppSettings["tenantId"];