Reading settings from a Azure Function

You can use System.Environment.GetEnvironmentVariable like this:

var value = Environment.GetEnvironmentVariable("your_key_here")

This gets settings whenever you're working locally or on Azure.

Note that for Azure Functions v2 this is no longer true. The following is from Jon Gallant's blog:

For Azure Functions v2, the ConfigurationManager is not supported and you must use the ASP.NET Core Configuration system:

1. Include the following using statement:

   using Microsoft.Extensions.Configuration;
   

2. Include the ExecutionContext as a parameter

   public static void Run(InboundMessage inboundMessage, 
       TraceWriter log,
       out string outboundMessage, 
       ExecutionContext context)
   

3. Get the IConfiguration Root

   var config = new ConfigurationBuilder()
       .SetBasePath(context.FunctionAppDirectory)
       .AddJsonFile("local.settings.json", optional: true, reloadOnChange: true)
       .AddEnvironmentVariables()
       .Build();
   

4. And use it to reference AppSettings keys

   var password = config["password"]
   

When debugging locally, it gets the settings from local.settings.json under the "Values" keyword. When running in Azure, it gets the settings from the Application settings tab.