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This article mainly introduces the relevant knowledge of how to configure the environment in ASP.NET Core, the content is detailed and easy to understand, the operation is simple and fast, and it has a certain reference value. I believe you will gain something after reading this article on how to configure the environment in ASP.NET Core. Let's take a look.

1. Environment variable configuration

ASP.NET Core reads the environment variable (Properties\ launchSettings.json) ASPNETCORE_ENVIRONMENT when the application starts and stores that value in IHostingEnvironment.EnvironmentName. ASPNETCORE_ENVIRONMENT can be set to any value, but the framework supports only three values: Development (development), Staging (phased), and Production (production). If ASPNETCORE_ENVIRONMENT is not set, it defaults to Production.

Public void Configure (IApplicationBuilder app, IHostingEnvironment env) {if (env.IsDevelopment ()) {app.UseDeveloperExceptionPage ();} if (env.IsProduction () | | env.IsStaging () | | env.IsEnvironment ("Staging_2")) {app.UseExceptionHandler ("/ Error");}}

The configuration in Properties/launchSettings.json is as follows:

When ASPNETCORE_ENVIRONMENT is set to Development, UseDeveloperExceptionPage is called.

When ASPNETCORE_ENVIRONMENT is set to Staging, Production, UseExceptionHandler is called.

two。 Development environment configuration

The development environment can enable features that should not be exposed in production. For example, the developer exception page is enabled only in the development environment. The local computer development environment can be set in the Properties\ launchSettings.json file of the project. The environment value set in launchSettings.json overrides the value set in the system environment. The three profiles shown in the following launchSettings.json files:

{"iisSettings": {"windowsAuthentication": false, "anonymousAuthentication": true, "iisExpress": {"applicationUrl": "http://localhost:54339/"," sslPort ": 0}}," profiles ": {" IISExpress ": {" commandName ":" IISExpress "," launchBrowser ": true," environmentVariables ": {" ASPNETCORE_My_Environment ":" 1 " "ASPNETCORE_DETAILEDERRORS": "1", "ASPNETCORE_ENVIRONMENT": "Development"}, "EnvironmentsSample": {"commandName": "Project", "launchBrowser": true, "environmentVariables": {"ASPNETCORE_ENVIRONMENT": "Production"}, "applicationUrl": "http://localhost:54340;" Http://localhost:54341"}, "Kestrel Staging": {"commandName": "Project", "launchBrowser": true, "environmentVariables": {"ASPNETCORE_My_Environment": "1", "ASPNETCORE_DETAILEDERRORS": "1", "ASPNETCORE_ENVIRONMENT": "Staging"}, "applicationUrl": "http://localhost:51997/"}

When you start an application using dotnet run, the first configuration file with "commandName": "IISExpress" is used. The value of commandName is to specify the Web server to start. The applicationUrl attribute in launchSettings.json also specifies the list of server URL. Use semicolons between URL in the list, such as the applicationUrl attribute value configuration in EnvironmentsSample in the environment configuration above. GUI is also available in the debug tab of the Visual Studio project properties to edit the launchSettings.json file:

Changes to the project configuration file may not take effect until the Web server is restarted. Kestrel must be restarted to detect changes to the environment configuration.

Now to verify that the developer exception page example is enabled in the development environment, first debug and start the first configuration file (IISExpress):

3. Production environment configuration

The Production environment should be configured to maximize security, performance, and application reliability. Some common settings that are different from development include:

Cache.

Client resources are bundled and shrunk and may be provided from CDN (Network Distribution).

The diagnostic error page has been disabled.

The friendly error page is enabled.

Production logging and monitoring are enabled. For example, Application Insights.

Now let's verify that the friendly error page example is enabled in the production environment, first debug and start the second configuration file (EnvironmentsSample):

4. Startup classes and methods based on environment configuration

When an ASP.NET Core application starts, the application can define separate Startup classes (for example, StartupDevelopment) for different environments, and the corresponding Startup class will choose the environment configuration at run time. Priority is given to Startup classes whose name suffixes match the current environment. If no matching Startup {EnvironmentName} is found, the original Startup class is used. To implement an environment-based Startup class, create a Startup {EnvironmentName} class for each environment in use:

Public class StartupDevelopment {public void ConfigureServices (IServiceCollection services) {} public void Configure (IApplicationBuilder app, IHostingEnvironment env) {} public class StartupProduction {public void ConfigureServices (IServiceCollection services) {} public void Configure (IApplicationBuilder app, IHostingEnvironment env) {}}

Overload using UseStartup (IWebHostBuilder, String) that accepts the assembly name:

Public class Program {public static void Main (string [] args) {CreateWebHostBuilder (args). Build (). Run ();} public static IWebHostBuilder CreateWebHostBuilder (string [] args) {var assemblyName = typeof (Startup). GetTypeInfo (). Assembly.FullName; return WebHost.CreateDefaultBuilder (args) .UseStartup (assemblyName);}}

Start the second configuration file (EnvironmentsSample) by debugging to see the effect:

Because debugging starts the production (Production) environment of the second configuration file (EnvironmentsSample), the Startup class will find the corresponding Startup class and load it for the current environment configuration when running the selection.

This is the end of the article on "how to configure the environment in ASP.NET Core". Thank you for reading! I believe you all have a certain understanding of the knowledge of "how to configure the environment in ASP.NET Core". If you want to learn more, you are welcome to follow the industry information channel.

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