/// <summary>
/// Builds the required services and an <see cref="IWebHost"/> which hosts a web application.
/// </summary>
public IWebHost Build()
{
if (_webHostBuilt)
{
throw new InvalidOperationException(Resources.WebHostBuilder_SingleInstance);
}
_webHostBuilt = true;
var hostingServices = BuildCommonServices(out var hostingStartupErrors);
var applicationServices = hostingServices.Clone();
var hostingServiceProvider = hostingServices.BuildServiceProvider();
if (!_options.SuppressStatusMessages)
{
// Warn about deprecated environment variables
if (Environment.GetEnvironmentVariable("Hosting:Environment") != null)
{
Console.WriteLine("The environment variable 'Hosting:Environment' is obsolete and has been replaced with 'ASPNETCORE_ENVIRONMENT'");
}
if (Environment.GetEnvironmentVariable("ASPNET_ENV") != null)
{
Console.WriteLine("The environment variable 'ASPNET_ENV' is obsolete and has been replaced with 'ASPNETCORE_ENVIRONMENT'");
}
if (Environment.GetEnvironmentVariable("ASPNETCORE_SERVER.URLS") != null)
{
Console.WriteLine("The environment variable 'ASPNETCORE_SERVER.URLS' is obsolete and has been replaced with 'ASPNETCORE_URLS'");
}
}
var logger = hostingServiceProvider.GetRequiredService <ILogger <WebHost> >();
// Warn about duplicate HostingStartupAssemblies
foreach (var assemblyName in _options.GetFinalHostingStartupAssemblies().GroupBy(a => a, StringComparer.OrdinalIgnoreCase).Where(g => g.Count() > 1))
{
logger.LogWarning($"The assembly {assemblyName} was specified multiple times. Hosting startup assemblies should only be specified once.");
}
AddApplicationServices(applicationServices, hostingServiceProvider);
var host = new WebHost(
applicationServices,
hostingServiceProvider,
_options,
_config,
hostingStartupErrors);
host.Initialize();
return(host);
}
public virtual async Task StartAsync(CancellationToken cancellationToken = default)
{
Debug.Assert(_applicationServices != null, "Initialize must be called first.");
HostingEventSource.Log.HostStart();
_logger = _applicationServices.GetRequiredService <ILoggerFactory>().CreateLogger("Microsoft.AspNetCore.Hosting.Diagnostics");
_logger.Starting();
var application = BuildApplication();
_applicationLifetime = _applicationServices.GetRequiredService <ApplicationLifetime>();
_hostedServiceExecutor = _applicationServices.GetRequiredService <HostedServiceExecutor>();
// Fire IHostedService.Start
await _hostedServiceExecutor.StartAsync(cancellationToken).ConfigureAwait(false);
var diagnosticSource = _applicationServices.GetRequiredService <DiagnosticListener>();
var activitySource = _applicationServices.GetRequiredService <ActivitySource>();
var httpContextFactory = _applicationServices.GetRequiredService <IHttpContextFactory>();
var hostingApp = new HostingApplication(application, _logger, diagnosticSource, activitySource, httpContextFactory);
await Server.StartAsync(hostingApp, cancellationToken).ConfigureAwait(false);
_startedServer = true;
// Fire IApplicationLifetime.Started
_applicationLifetime?.NotifyStarted();
_logger.Started();
// Log the fact that we did load hosting startup assemblies.
if (_logger.IsEnabled(LogLevel.Debug))
{
foreach (var assembly in _options.GetFinalHostingStartupAssemblies())
{
_logger.StartupAssemblyLoaded(assembly);
}
}
if (_hostingStartupErrors != null)
{
foreach (var exception in _hostingStartupErrors.InnerExceptions)
{
_logger.HostingStartupAssemblyError(exception);
}
}
}
private void ExecuteHostingStartups()
{
var webHostOptions = new WebHostOptions(_config, Assembly.GetEntryAssembly()?.GetName().Name ?? string.Empty);
if (webHostOptions.PreventHostingStartup)
{
return;
}
var exceptions = new List <Exception>();
var processed = new HashSet <Assembly>();
_hostingStartupWebHostBuilder = new HostingStartupWebHostBuilder(this);
// Execute the hosting startup assemblies
foreach (var assemblyName in webHostOptions.GetFinalHostingStartupAssemblies())
{
try
{
var assembly = Assembly.Load(new AssemblyName(assemblyName));
if (!processed.Add(assembly))
{
// Already processed, skip it
continue;
}
foreach (var attribute in assembly.GetCustomAttributes <HostingStartupAttribute>())
{
var hostingStartup = (IHostingStartup)Activator.CreateInstance(attribute.HostingStartupType) !;
hostingStartup.Configure(_hostingStartupWebHostBuilder);
}
}
catch (Exception ex)
{
// Capture any errors that happen during startup
exceptions.Add(new InvalidOperationException($"Startup assembly {assemblyName} failed to execute. See the inner exception for more details.", ex));
}
}
if (exceptions.Count > 0)
{
_hostingStartupErrors = new AggregateException(exceptions);
}
}
private IServiceCollection BuildCommonServices(out AggregateException hostingStartupErrors)
{
hostingStartupErrors = null;
_options = new WebHostOptions(_config, Assembly.GetEntryAssembly()?.GetName().Name);
if (!_options.PreventHostingStartup)
{
var exceptions = new List <Exception>();
// Execute the hosting startup assemblies
foreach (var assemblyName in _options.GetFinalHostingStartupAssemblies().Distinct(StringComparer.OrdinalIgnoreCase))
{
try
{
var assembly = Assembly.Load(new AssemblyName(assemblyName));
foreach (var attribute in assembly.GetCustomAttributes <HostingStartupAttribute>())
{
var hostingStartup = (IHostingStartup)Activator.CreateInstance(attribute.HostingStartupType);
hostingStartup.Configure(this);
}
}
catch (Exception ex)
{
// Capture any errors that happen during startup
exceptions.Add(new InvalidOperationException($"Startup assembly {assemblyName} failed to execute. See the inner exception for more details.", ex));
}
}
if (exceptions.Count > 0)
{
hostingStartupErrors = new AggregateException(exceptions);
}
}
var contentRootPath = ResolveContentRootPath(_options.ContentRootPath, AppContext.BaseDirectory);
// Initialize the hosting environment
_hostingEnvironment.Initialize(contentRootPath, _options);
_context.HostingEnvironment = _hostingEnvironment;
var services = new ServiceCollection();
services.AddSingleton(_options);
services.AddSingleton <IHostingEnvironment>(_hostingEnvironment);
services.AddSingleton <Extensions.Hosting.IHostingEnvironment>(_hostingEnvironment);
services.AddSingleton(_context);
var builder = new ConfigurationBuilder()
.SetBasePath(_hostingEnvironment.ContentRootPath)
.AddConfiguration(_config);
_configureAppConfigurationBuilder?.Invoke(_context, builder);
var configuration = builder.Build();
services.AddSingleton <IConfiguration>(configuration);
_context.Configuration = configuration;
var listener = new DiagnosticListener("Microsoft.AspNetCore");
services.AddSingleton <DiagnosticListener>(listener);
services.AddSingleton <DiagnosticSource>(listener);
services.AddTransient <IApplicationBuilderFactory, ApplicationBuilderFactory>();
services.AddTransient <IHttpContextFactory, HttpContextFactory>();
services.AddScoped <IMiddlewareFactory, MiddlewareFactory>();
services.AddOptions();
services.AddLogging();
// Conjure up a RequestServices
services.AddTransient <IStartupFilter, AutoRequestServicesStartupFilter>();
services.AddTransient <IServiceProviderFactory <IServiceCollection>, DefaultServiceProviderFactory>();
// Ensure object pooling is available everywhere.
services.AddSingleton <ObjectPoolProvider, DefaultObjectPoolProvider>();
if (!string.IsNullOrEmpty(_options.StartupAssembly))
{
try
{
var startupType = StartupLoader.FindStartupType(_options.StartupAssembly, _hostingEnvironment.EnvironmentName);
if (typeof(IStartup).GetTypeInfo().IsAssignableFrom(startupType.GetTypeInfo()))
{
services.AddSingleton(typeof(IStartup), startupType);
}
else
{
services.AddSingleton(typeof(IStartup), sp =>
{
var hostingEnvironment = sp.GetRequiredService <IHostingEnvironment>();
var methods = StartupLoader.LoadMethods(sp, startupType, hostingEnvironment.EnvironmentName);
return(new ConventionBasedStartup(methods));
});
}
}
catch (Exception ex)
{
var capture = ExceptionDispatchInfo.Capture(ex);
services.AddSingleton <IStartup>(_ =>
{
capture.Throw();
return(null);
});
}
}
_configureServices?.Invoke(_context, services);
return(services);
}
/// <summary>
/// Builds the required services and an <see cref="IWebHost"/> which hosts a web application.
/// </summary>
public IWebHost Build()
{
if (_webHostBuilt)
{
throw new InvalidOperationException(Resources.WebHostBuilder_SingleInstance);
}
_webHostBuilt = true;
var hostingServices = BuildCommonServices(out var hostingStartupErrors);
var applicationServices = hostingServices.Clone();
var hostingServiceProvider = GetProviderFromFactory(hostingServices);
if (!_options.SuppressStatusMessages)
{
// Warn about deprecated environment variables
if (Environment.GetEnvironmentVariable("Hosting:Environment") != null)
{
Console.WriteLine("The environment variable 'Hosting:Environment' is obsolete and has been replaced with 'ASPNETCORE_ENVIRONMENT'");
}
if (Environment.GetEnvironmentVariable("ASPNET_ENV") != null)
{
Console.WriteLine("The environment variable 'ASPNET_ENV' is obsolete and has been replaced with 'ASPNETCORE_ENVIRONMENT'");
}
if (Environment.GetEnvironmentVariable("ASPNETCORE_SERVER.URLS") != null)
{
Console.WriteLine("The environment variable 'ASPNETCORE_SERVER.URLS' is obsolete and has been replaced with 'ASPNETCORE_URLS'");
}
}
AddApplicationServices(applicationServices, hostingServiceProvider);
var host = new WebHost(
applicationServices,
hostingServiceProvider,
_options,
_config,
hostingStartupErrors);
try
{
host.Initialize();
var logger = host.Services.GetRequiredService <ILogger <WebHost> >();
// Warn about duplicate HostingStartupAssemblies
foreach (var assemblyName in _options.GetFinalHostingStartupAssemblies().GroupBy(a => a, StringComparer.OrdinalIgnoreCase).Where(g => g.Count() > 1))
{
logger.LogWarning($"The assembly {assemblyName} was specified multiple times. Hosting startup assemblies should only be specified once.");
}
return(host);
}
catch
{
// Dispose the host if there's a failure to initialize, this should clean up
// will dispose services that were constructed until the exception was thrown
host.Dispose();
throw;
}
IServiceProvider GetProviderFromFactory(IServiceCollection collection)
{
var provider = collection.BuildServiceProvider();
var factory = provider.GetService <IServiceProviderFactory <IServiceCollection> >();
if (factory != null && !(factory is DefaultServiceProviderFactory))
{
using (provider)
{
return(factory.CreateServiceProvider(factory.CreateBuilder(collection)));
}
}
return(provider);
}
}
