AspNetCore.Docs/aspnetcore/blazor/fundamentals/environments.md

title	author	description	monikerRange	ms.author	ms.custom	ms.date	no-loc	uid
ASP.NET Core Blazor environments	guardrex	Learn about environments in Blazor, including how to set the environment of a Blazor WebAssembly app.	>= aspnetcore-3.1	riande	mvc	06/10/2020	ASP.NET Core Identity cookie Cookie Blazor Blazor Server Blazor WebAssembly Identity Let's Encrypt Razor SignalR	blazor/fundamentals/environments

ASP.NET Core Blazor environments

[!NOTE] This topic applies to Blazor WebAssembly. For general guidance on ASP.NET Core app configuration, see xref:fundamentals/environments.

When running an app locally, the environment defaults to Development. When the app is published, the environment defaults to Production.

A hosted Blazor WebAssembly app picks up the environment from the server via a middleware that communicates the environment to the browser by adding the blazor-environment header. The value of the header is the environment. The hosted Blazor app and the server app share the same environment. For more information, including how to configure the environment, see xref:fundamentals/environments.

For a standalone app running locally, the development server adds the blazor-environment header to specify the Development environment. To specify the environment for other hosting environments, add the blazor-environment header.

In the following example for IIS, add the custom header to the published web.config file. The web.config file is located in the bin/Release/{TARGET FRAMEWORK}/publish folder:

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.webServer>

    ...

    <httpProtocol>
      <customHeaders>
        <add name="blazor-environment" value="Staging" />
      </customHeaders>
    </httpProtocol>
  </system.webServer>
</configuration>

[!NOTE] To use a custom web.config file for IIS that isn't overwritten when the app is published to the publish folder, see xref:blazor/host-and-deploy/webassembly#use-a-custom-webconfig.

Obtain the app's environment in a component by injecting xref:Microsoft.AspNetCore.Components.WebAssembly.Hosting.IWebAssemblyHostEnvironment and reading the xref:Microsoft.AspNetCore.Components.WebAssembly.Hosting.IWebAssemblyHostEnvironment.Environment property:

@page "/"
@using Microsoft.AspNetCore.Components.WebAssembly.Hosting
@inject IWebAssemblyHostEnvironment HostEnvironment

<h1>Environment example</h1>

<p>Environment: @HostEnvironment.Environment</p>

During startup, the xref:Microsoft.AspNetCore.Components.WebAssembly.Hosting.WebAssemblyHostBuilder exposes the xref:Microsoft.AspNetCore.Components.WebAssembly.Hosting.IWebAssemblyHostEnvironment through the xref:Microsoft.AspNetCore.Components.WebAssembly.Hosting.WebAssemblyHostBuilder.HostEnvironment property, which enables developers to have environment-specific logic in their code:

if (builder.HostEnvironment.Environment == "Custom")
{
    ...
};

The following convenience extension methods permit checking the current environment for Development, Production, Staging, and custom environment names:

• IsDevelopment()
• IsProduction()
• IsStaging()
• IsEnvironment("{ENVIRONMENT NAME}")

if (builder.HostEnvironment.IsStaging())
{
    ...
};

if (builder.HostEnvironment.IsEnvironment("Custom"))
{
    ...
};

The xref:Microsoft.AspNetCore.Components.WebAssembly.Hosting.IWebAssemblyHostEnvironment.BaseAddress?displayProperty=nameWithType property can be used during startup when the xref:Microsoft.AspNetCore.Components.NavigationManager service isn't available.

Additional resources

• xref:fundamentals/environments