DI in Azure Functions

Question

I have some class libraries that I use in my ASP.NET Web API app that handle all my backend stuff e.g. CRUD operations to multiple databases like Azure SQL Database, Cosmos DB, etc.

I don't want to re-invent the wheel and able to use them in a new Azure Functions that I'm creating in Visual Studio 2017. All my repository methods use an interface. So, how will I implement dependency injection in my new Azure function?

I'm not seeing any support for DI but I'm a bit confused. It appears Azure Functions are based on the same SDK as WebJobs and I think last year Microsoft had started supporting DI in WebJobs - I know for sure because I implemented it using Ninject.

Is there way around this so that I can use my existing libraries in my new Azure Functions project?

Answer 1

I see these two techniques in addition to the service locator (anti)pattern. I asked the Azure Functions team for their comments as well.

https://blog.wille-zone.de/post/azure-functions-dependency-injection/

https://blog.wille-zone.de/post/azure-functions-proper-dependency-injection/

Answer 2

There is an open feature request on the GitHub pages for Azure Functions concerning this matter.

However, the way I'm approaching this is using some kind of 'wrapper' entry point, resolve this using the service locator and and start the function from there.

This looks a bit like this (simplified)

var builder = new ContainerBuilder(); //register my types  var container = builder.Build();  using(var scope = container.BeginLifetimeScope()) {   var functionLogic = scope.Resolve<IMyFunctionLogic>();    functionLogic.Execute(); } 

This is a bit hacky of course, but it's the best there is until there is at the moment (to my knowledge).