ASP.NET Core: Use Keys Stored in appsettings.json in .NET 6 and Later

This article requires .NET 6 as a minimum.

In .NET 6, it was made easy to use the custom keys in appsettings.json. The WebApplicationBuilder has a configuration object as a property that can be used.

Modify the appsettings.json as in this example.

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*",
  "MyCustomKey": "Some string value...",
  "SecretAuthenticationKey": "396B5DD9-CC75-411C-9311-5B6E1F391B89"
}

Modify the Program.cs as in this example snippet.

var builder = WebApplication.CreateBuilder(args);
 
// ...

string myCustomKey = builder.Configuration["MyCustomKey"]; // NOTE: do something with myCustomKey
string jwtSecretKey = builder.Configuration["SecretAuthenticationKey"]; // NOTE: use jwtSecretKey for the Secret Key in the JWT Bearer Authentication examples of this site

Alternate/Custom JSON Configuration Files

Also, import custom JSON configuration files to use. Create custom.json as follows.

{
  "Custom": {
    "Level": {
      "Default": "1"
    }
  },
  "SecretAuthenticationKey": "396B5DD9-CC75-411C-9311-5B6E1F391B89"
}

To use the above JSON settings file:

IConfiguration config = new ConfigurationBuilder().AddJsonFile("custom.json").Build(); // NOTE: custom.json could include its full path using Path.Combine() and the ContentRootPath property of the IWebHostEnvironment interface

string myCustomLevelDefault = config["Custom:Level:Default"]; // NOTE: do something with myCustomLevelDefault, which equals "1"
string jwtSecretKey = config["SecretAuthenticationKey"]; // NOTE: use jwtSecretKey for the Secret Key in the JWT Bearer Authentication examples of this site

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