Application with appsettings.json

Learn to manage environment-specific settings, integrate configuration with dependency injection, and apply best practices for secure and efficient application configuration in C#.

Introduction

Welcome to the world of configuration management in ASP.NET Core! In this developer-focused guide, we'll dive deep into the power of appsettings.json, the go-to file for customizing your application's behavior across different environments. Let's roll up our sleeves and explore the ins and outs of configuring your app for Development (DEV), Production (PROD), and beyond.

1. Setting the Stage with appsettings.json

Let's kick things off by creating our appsettings.json file, the central hub for all our configuration settings.

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "System": "Warning"
    }
  },
  "AllowedHosts": "*"
}

2. Tailoring for Development (DEV) Environment

In the DEV environment, we might want detailed logging and a local database connection. Let's tweak our appsettings.json to reflect these settings.

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=dev-server;Database=mydatabase;User=devuser;Password=devpassword;"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Debug",
      "Microsoft": "Information",
      "System": "Information"
    }
  }
}

3. Optimizing for Production (PROD) Environment

When it comes to PROD, we'll switch to a different database connection and adjust our logging levels for optimal performance.

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=prod-server;Database=mydatabase;User=produser;Password=prodpassword;"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "System": "Warning"
    }
  }
}

4. Harnessing the Power of Configuration Providers

Let's level up our configuration game by adding the ability to override settings using environment variables and securely store sensitive data with User Secrets.

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
    WebHost.CreateDefaultBuilder(args)
        .ConfigureAppConfiguration((hostingContext, config) =>
        {
            config.AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
                  .AddJsonFile($"appsettings.{hostingContext.HostingEnvironment.EnvironmentName}.json", optional: true)
                  .AddEnvironmentVariables();
        })
        .UseStartup<Startup>();

5. Seamlessly Switching Environments

Make environment switching a breeze by utilizing launch profiles in Visual Studio or passing command-line arguments when running your application.

"profiles": {
  "Development": {
    "commandName": "Project",
    "environmentVariables": {
      "ASPNETCORE_ENVIRONMENT": "Development"
    }
  },
  "Production": {
    "commandName": "Project",
    "environmentVariables": {
      "ASPNETCORE_ENVIRONMENT": "Production"
    }
  }
}

6. Crafting Clean and Maintainable Configurations

Adopt best practices for structuring your appsettings.json file, grouping related settings logically, and using clear naming conventions for easy maintenance.

7. Ensuring Configuration Consistency with Unit Tests

Validate the correctness of your configurations with unit tests, ensuring that settings are applied correctly across all environments.

public class ConfigurationTests
{
    [Fact]
    public void ShouldHaveDevelopmentLoggingLevelDebug()
    {
        var config = new ConfigurationBuilder()
            .AddJsonFile("appsettings.Development.json")
            .Build();

        var logLevel = config["Logging:LogLevel:Default"];
        Assert.Equal("Debug", logLevel);
    }
}

Ready to Tackle Configuration in ASP.NET Core?

With appsettings.json as our ally, we've unlocked the power to configure our ASP.NET Core applications with precision and agility. Let's navigate the world of environment-based settings, configuration providers, and best practices to create applications that are flexible, robust, and ready for any environment.