Autofac.Extensions.DependencyInjection.AzureFunctions

Autofac is an IoC container for Microsoft .NET. It manages the dependencies between classes so that applications stay easy to change as they grow in size and complexity. This is achieved by treating regular .NET classes as components.

This library has been created to allow Azure Functions v3 users to use AutoFac library in a common way like it is done with regular web projects. Note that Azure Functions moving forward has now a NET 5 dotnet-isolated mode which allows the use of Autofac directly without this library.

Please file issues and pull requests for this package in this repository rather than in the Autofac core repo.

• NuGet
• Contributing - You can report problems and feature requests creating issues and pull requests on this project.

Get Started in Azure Functions

This quick start shows how to use the UseAutofacServiceProviderFactory integration to help automatically build the root service provider for you.

• Reference the Autofac.Extensions.DependencyInjection.AzureFunctions package from NuGet.
• Create your Startup class, following the documentation on how to Use dependency injection in .NET Azure Functions
• In your Configure method, where you configure the IFunctionsHostBuilder, call UseAutofacServiceProviderFactory(ConfigureContainer) to hook Autofac into the startup pipeline.
• In the ConfigureContainer method of your Startup class register things directly into an Autofac ContainerBuilder.
• If you want to use functions declared in referenced projects, add <FunctionsInDependencies>true</FunctionsInDependencies> to the <PropertyGroup> of your main Azure Functions project.

The IServiceProvider will automatically be created for you, so there's nothing you have to do but register things.

using Microsoft.Azure.Functions.Extensions.DependencyInjection;

[assembly: FunctionsStartup(typeof(Startup))]

public class Startup : FunctionsStartup
{
    public override void Configure(IFunctionsHostBuilder builder)
    {
        builder
            // This is the required call in order to use autofac in your azure functions app
            .UseAutofacServiceProviderFactory(ConfigureContainer);
    }

    public override void ConfigureAppConfiguration(IFunctionsConfigurationBuilder builder)
    {
        // this is optional and will bind IConfiguration with appsettings.json in
        // the container, like it is usually done in regular dotnet console and
        // web applications.
        builder.UseAppSettings();
    }

    private IContainer ConfigureContainer(ContainerBuilder builder)
    {
        builder
            .Register(activator =>
            {
                // Example on how to bind settings from appsettings.json
                // to a class instance
                var section = activator.Resolve<IConfiguration>().GetSection(nameof(MySettings));

                var instance = section.Get<MySettings>();

                // If you expect IConfiguration to change (with reloadOnChange=true), use
                // token to rebind.
                ChangeToken.OnChange(
                    () => section.GetReloadToken(),
                    (state) => section.Bind(state),
                    instance);

                return instance;
            })
            .AsSelf()
            .SingleInstance();



        // Register all functions that resides in a given namespace
        // The function class itself will be created using autofac
        builder
            .RegisterAssemblyTypes(typeof(Startup).Assembly)
            .InNamespace("MyNamespace.Functions")
            .AsSelf() // Azure Functions core code resolves a function class by itself.
            .InstancePerTriggerRequest(); // This will scope nested dependencies to each function execution

        builder
            .RegisterAssemblyTypes(typeof(Startup).Assembly)
            .InNamespace("MyNamespace.Services")
            .AsImplementedInterfaces()
            .InstancePerTriggerRequest();


        
        var appContainer = builder.Build();

        // If you need a Multi-Tenant Container, use this code instead of plain appContainer;

        // var multiTenant = new MultitenantContainer(tenantIdentificationStrategy, appContainer);
        // return multiTenant

        return appContainer;

    }
}

This is a basic function example, observe that classes and functions are not declared as static:

    public class Function1 : Disposable
    {
        public Function1(IService1 service1, ILogger logger)
        {
            // ...
        }

        [FunctionName(nameof(Function1))]
        public async Task Run([QueueTrigger("myqueue-items", Connection = "AzureWebJobsStorage")]string myQueueItem)
        {
            await Task.Delay(2000);
            _logger.LogInformation($"C# Queue trigger function processed: {myQueueItem}");
        }

        // ...
    }

Get Help from Autofac Official Library

Need help with Autofac? They have a documentation site as well as API documentation. They're ready to answer your questions on Stack Overflow or check out the discussion forum.

• Documentation - .NET Core Integration
• Documentation - ASP.NET Core Integration

Before heading to their support channels, make sure your issue is related to the main official library by creating an isolated test project without this package.