private IFunctionsRequestHandler BuildFunctionsRequestHandler(IFunctionsHostBuilder builder)
{
IWebHostEnvironment webHostEnv;
using (var functionsServiceProvider = builder.Services.BuildServiceProvider())
{
var functionsHostingEnv = functionsServiceProvider.GetRequiredService <IHostEnvironment>();
webHostEnv = CreateWebHostEnvironment(functionsHostingEnv);
}
var config = CreateConfiguration(webHostEnv);
ServiceCollection applicationServices = CreateBasicApplicationServices(webHostEnv, config);
// build service collection used for creating an instance of TStartup.
var startupServices = new ServiceCollection();
startupServices.AddSingleton(config);
startupServices.AddSingleton(webHostEnv);
startupServices.AddSingleton <IHostEnvironment>(webHostEnv);
TStartup startupInstance;
using (var startupServiceProvider = startupServices.BuildServiceProvider())
{
startupInstance = ActivatorUtilities.CreateInstance <TStartup>(startupServiceProvider);
}
var startupMethods = typeof(TStartup).GetMethods().ToList();
// get ConfigureServices method of TStartup
var configureServicesMethod = startupMethods
.SingleOrDefault(mi => string.Equals(mi.Name, "ConfigureServices", StringComparison.InvariantCulture));
// invoke ConfigureService method from instance of TStartUp if exists.
var configureServicesResult = configureServicesMethod?.Invoke(startupInstance, new object[] { applicationServices });
// if the ConfigureService method returns a ServiceProvider we use this provider for the application. If not, we build it :)
var applicationServiceProvider = configureServicesResult as IServiceProvider ?? applicationServices.BuildServiceProvider();
var applicationBuilder = new ApplicationBuilder(applicationServiceProvider, new FeatureCollection());
var configureMethod = startupMethods
.SingleOrDefault(mi => string.Equals(mi.Name, "Configure", StringComparison.InvariantCulture));
if (configureMethod != null)
{
InvokeConfigure(configureMethod, startupInstance, applicationBuilder);
}
var requestDelegate = applicationBuilder.Build();
var functionRequestHandler = new FunctionsRequestHandler(applicationBuilder.ApplicationServices, requestDelegate);
return(functionRequestHandler);
}
public static IHostBuilder ConfigureWebAppFunctionHost <TStartup>(this IHostBuilder builder) where TStartup : class
{
try
{
var factory = new WebApplicationFactory <TStartup>();
var client = factory.CreateClient(new WebApplicationFactoryClientOptions
{
AllowAutoRedirect = false
});
var requestHandler = new FunctionsRequestHandler(client);
return(builder.ConfigureServices(services =>
{
services.AddSingleton <IFunctionsRequestHandler>(requestHandler);
}));
}
catch (Exception e)
{
Console.Error.WriteLine(e);
// log startup exceptions to application insights if instrumentation key is available.
var appInsightsInstrumentationKey = Environment.GetEnvironmentVariable("APPINSIGHTS_INSTRUMENTATIONKEY", EnvironmentVariableTarget.Process);
if (!string.IsNullOrWhiteSpace(appInsightsInstrumentationKey))
{
#pragma warning disable CS0618 // Type or member is obsolete
// TODO: Check if the telemetry client can be resolved somehow.
var telemetryClient = new TelemetryClient {
InstrumentationKey = appInsightsInstrumentationKey
};
#pragma warning restore CS0618 // Type or member is obsolete
telemetryClient.TrackException(e);
}
throw;
}
}