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EnvironmentName

As explained in ASP.NET Core in Action, 3e

EnvironmentName is the hosting-environment property that identifies the current application environment, such as Development, Staging, or Production.

EnvironmentName identifies the environment in which an ASP.NET Core application is running. Set through ASPNETCORE_ENVIRONMENT, it commonly uses Development, Staging, or Production. section 10.4.1

Use the hosting environment to vary application behavior:

  • Check environments with IsDevelopment(), IsStaging(), IsProduction(), or IsEnvironment(string); these methods compare names case-insensitively. section 10.4.1
  • Load an optional appsettings.{EnvironmentName}.json file after appsettings.json so environment-specific values override shared settings. section 10.4.2
  • Include providers such as User Secrets only in Development, or select different middleware for development and deployed environments. section 10.4.2

Environment-specific configuration

Read the current environment from builder.Environment, then add appsettings.json followed by an optional file whose name includes env.EnvironmentName. A Development run can therefore load appsettings.Development.json after the shared settings.

Listing 10.13 Adding environment-specific appsettings.json files
WebApplicationBuilder builder = WebApplication.CreateBuilder(args);
 
IHostEnvironment env = builder.Environment;           #1
 
builder.Configuration.Sources.Clear();
builder.Configuration
    .AddJsonFile(
        "appsettings.json",
        optional: false)                              #2
    .AddJsonFile(                                     #3
        $”appsettings.{env.EnvironmentName}.json”,    #3
        Optional: true);                              #3
 
WebApplication app = builder.Build();
 
app.MapGet("/", () =>"Hello world!");
 
app.Run();
#1 The current IHostEnvironment is available on WebApplicationBuilder.
#2 It’s common to make the base appsettings.json compulsory.
#3 Adds an optional environment-specific JSON file where the filename varies with the environment

Inspect a runnable Program.cs example that builds environment-specific configuration with WebApplicationBuilder. section 10.4.2

How ASP.NET Core in Action, 3e covers it

How deep it goes
Explains the environment variable, standard names, helper methods, configuration loading, and middleware customization without detailing bootstrap internals.
Examples
Demonstrates environment-specific JSON files, conditional User Secrets, and production exception-handling middleware.
What you can do after
Operate/configure an ASP.NET Core application with environment-specific settings, providers, and middleware.
How it connects
Connects EnvironmentName with IHostEnvironment, ASPNETCORE_ENVIRONMENT, configuration providers, appsettings files, and middleware.
Cover of ASP.NET Core in Action, 3e
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Related concepts

This explainer was generated by Manning's knowledge graph from the text of ASP.NET Core in Action, 3e. The section links point to the parts of the book it draws on.