ASP.NET Core Razor Pages

Inject Configuration

Inject the configuration by adding the following two lines at the top of your page:

@using Microsoft.Extensions.Configuration
@inject IConfiguration Configuration

Then access the value like:

@Configuration["ApplicationInsights:InstrumentationKey"]

Options pattern

Inject IOptionsMonitor<MyOptions> with an @inject directive:

@using Microsoft.Extensions.Options
@inject IOptions<ApplicationInsightsOptions> ApplicationInsightsOptionsAccessor

Then access the value like:

var instrumentationKey = ApplicationInsightsOptionsAccessor.Value.InstrumentationKey;

Additional information at Options pattern in ASP.NET Core | Microsoft Docs