Basic dependency injection for Azure functions V2
This is basic dependency injection library we are using in our projects for Azure Functions V2. Available as nuget
First of all you have to declare Startup class for your azure function
[assembly: WebJobsStartup(typeof(Startup))]
namespace Watts.Utilities.Readings.Integration
{
public class Startup : IWebJobsStartup
{
public void Configure(IWebJobsBuilder builder)
{
builder.UseServiceProvider<AutofacScopedServiceProvider>();
}
}
}
and then use builder.UseServiceProvider<>() extension to register custom IScopedServiceProvider
For Autofac implementation can be the following
public class AutofacScopedServiceProvider : IScopedServiceProvider
{
public IServiceProvider CurrentFor(IConfiguration configuration)
{
var builder = new ContainerBuilder();
builder.RegisterModule(new PersistenceModule(configuration));
return new AutofacServiceProvider(builder.Build());
}
}
IScopedServiceProvider has only one method you have to implement IServiceProvider CurrentFor(IConfiguration configuration), as you can see you get instence of IConfiguration, so you can easily access your configurations from local.settings.json
public class PersistenceModule
{
private readonly IConfiguration _configuration;
public PersistenceModule(IConfiguration configuration)
{
_configuration = configuration;
}
protected override void Load(ContainerBuilder builder)
{
builder.Register(c => new DatabaseContext(_configuration["DatabaseConnection"]));
builder.RegisterAssemblyTypes(typeof(StorageRepository<,>).Assembly)
.Where(t => t.Name.EndsWith("Repository") && !t.IsAbstract)
.AsImplementedInterfaces();
}
}
After all configuration is done, simply use [Import] attribute with you function method
public static async Task Integrate(
[ServiceBusTrigger(
"%topic%",
"%subscription%",
Connection = "ServiceBusConnection")]
Message meterContractImportedMessage,
[Import] ILogger log,
[Import] IService service)
{...}
When you are deploying your function into Azure environment you will encountered issue that extensions.json is not created properly. The issue is discussed here. To solve that we are using custom build targets, which will be included into your project with the nuget.