/// <summary>
/// Startup hooks are pieces of code that will run before a users program main executes
/// See: https://github.com/dotnet/core-setup/blob/master/Documentation/design-docs/host-startup-hook.md
/// </summary>
public static void Initialize()
{
if (!NativeMethods.IsAspNetCoreModuleLoaded())
{
// This means someone set the startup hook for Microsoft.AspNetCore.Server.IIS
// but are not running inprocess. Return at this point.
return;
}
var detailedErrors = Environment.GetEnvironmentVariable("ASPNETCORE_DETAILEDERRORS");
var enableStartupErrorPage = detailedErrors?.Equals("1", StringComparison.OrdinalIgnoreCase) ?? false;
enableStartupErrorPage |= detailedErrors?.Equals("true", StringComparison.OrdinalIgnoreCase) ?? false;
var aspnetCoreEnvironment = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT");
enableStartupErrorPage |= aspnetCoreEnvironment?.Equals("Development", StringComparison.OrdinalIgnoreCase) ?? false;
var dotnetEnvironment = Environment.GetEnvironmentVariable("DOTNET_ENVIRONMENT");
enableStartupErrorPage |= dotnetEnvironment?.Equals("Development", StringComparison.OrdinalIgnoreCase) ?? false;
if (!enableStartupErrorPage)
{
// Not running in development or detailed errors aren't enabled
return;
}
AppDomain.CurrentDomain.UnhandledException += (sender, eventArgs) =>
{
var exception = (Exception)eventArgs.ExceptionObject;
// Get the content root from IIS.
var iisConfigData = NativeMethods.HttpGetApplicationProperties();
var contentRoot = iisConfigData.pwzFullApplicationPath.TrimEnd(Path.DirectorySeparatorChar);
var model = ErrorPageModelBuilder.CreateErrorPageModel(
new PhysicalFileProvider(contentRoot),
logger: null,
showDetailedErrors: true,
exception);
var errorPage = new ErrorPage(model);
var stream = new MemoryStream();
// Never will go async because we are writing to a memory stream.
errorPage.ExecuteAsync(stream).GetAwaiter().GetResult();
// Get the raw content and set the error page.
stream.Position = 0;
var content = stream.ToArray();
NativeMethods.HttpSetStartupErrorPageContent(content);
};
}
public static RequestDelegate BuildErrorPageApplication(
IFileProvider contentRootFileProvider,
ILogger logger,
bool showDetailedErrors,
Exception exception)
{
if (exception is TargetInvocationException tae)
{
exception = tae.InnerException !;
}
var model = ErrorPageModelBuilder.CreateErrorPageModel(contentRootFileProvider, logger, showDetailedErrors, exception);
var errorPage = new ErrorPage(model);
return(context =>
{
context.Response.StatusCode = 500;
context.Response.Headers.CacheControl = "no-cache,no-store";
context.Response.Headers.Pragma = "no-cache";
context.Response.ContentType = "text/html; charset=utf-8";
return errorPage.ExecuteAsync(context);
});
}
