Proper way to access ILogger and IConfiguration inside Startup

[APIWT]

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Question

What is the proper way to get access to IConfiguration and ILogger inside a custom startup class?

[PureKrome]

@APIWT Have you tried experimenting with Azure Functions + Dependency Injection. Those docs show some examples.

Update :

ouch at all the downvotes. Feels like I'm on stack overflow now 😢

[espray]

This looks like a duplicate of #4464

[mhoeger]

@jeffhollan - looks like a good candidate for doc enhancements? I know @brettsam has answered similar questions for ILogger (here)

[APIWT]

The big issue with the ILogger suggestion is that it is not available in Startup. Plus, due to the bugs that currently exist with scoped services we are forced to do our own DI which is the bigger issue with functions as a whole currently.

[idg10]

The problem with the current design is that there doesn't seem to be a reliable way to get hold of the IConfiguration in your Startup.Configure method.

Apparently the only mechanism by which you can obtain IConfiguration is to have it injected as a dependency, which means it's only available after you've finished configuring all your services, and the service collection has been built. So what are you supposed to do if you need access to configuration settings as part of your service configuration code?

If you look at a typical ASP.NET Core startup class, it takes an IConfiguration as a constructor argument, for precisely this reason. It makes it possible to make configuration-driven decisions about how you configure services at startup.

So what I'd really like is for functions to support the same pattern. The host code that looks for an WebJobsStartupAttribute-annotated class would inspect the constructors of the startup class, and if there's a constructor that accepts an IConfiguration it should use that, passing the configuration, just like we get in ASP.NET Core apps.

[idg10]

Having looked into this a little more, it would appear that the ability to use startup classes at all in functions comes from the WebJobs SDK. So I created a draft PR Azure/azure-webjobs-sdk#2405 to show how this might be fixed. It's not terribly complex, and doesn't appear to require any changes to the Functions SDK itself. But before I go any further with this, can anyone from Microsoft let me know whether there's any interest in pursuing this change?

[carlosscastro]

Functions team, any update on this? The need to use IConfiguration during startup seems like a reasonable one and would align better with the pattern in asp.net core web apps.