In-Process .NET 8.0 upgrade errors: This service descriptor is keyed. Your service provider may not support keyed services.

[gallivantor]

.NET 8 In-Process function does not work if it references any packages that add Keyed Services to the collection (eg. Polly).

Microsoft.Azure.WebJobs.Script: Error configuring services in an external startup class.
Microsoft.Extensions.DependencyInjection.Abstractions: This service descriptor is keyed. Your service provider may not support keyed services.

Investigative information

Happens locally running in the Visual Studio emulator, as well as if deployed to Azure.

Seems to be due to the code in ConfigureAndLogUserConfiguredServices method of WebJobsBuilderExtensions checking the ImplementationType of all registered services, this throws an exception if a keyed service is registered.

Repro steps

1. Create an Azure Function using .NET 8.0 In-Process model.
2. Add a reference to Polly 8.4.1 from Nuget
3. Add the following code to Startup class's Configure method:

builder.Services.AddResiliencePipeline("my-key", builder =>
{
    builder.AddTimeout(TimeSpan.FromSeconds(10));
});

Expected behavior

Function app starts up as expected.

Actual behavior

Function App fails to start up:

Microsoft.Azure.WebJobs.Script: Error configuring services in an external startup class.
Microsoft.Extensions.DependencyInjection.Abstractions: This service descriptor is keyed. Your service provider may not support keyed services.

This is particularly dangerous because some Nuget packages change their behaviour when .net 8 is targeted and will perform a keyed registration - if ANY referenced package does this, the function app will not start up.

[gallivantor]

Related issue with dotnet runtime: dotnet/runtime#95789

[brettsam]

It doesn't seem that you are actually running the .NET 8 in-proc Function's host if you're seeing this. Can you see the host build version in either of the situations you see? I just tried this on latest versions of VS and it all worked as expected.

The docs for this migration are here -- https://learn.microsoft.com/en-us/azure/azure-functions/functions-dotnet-class-library?tabs=v4%2Ccmd#updating-to-target-net-8

[brettsam]

Going to close this as "not repro" but please let us know if you continue to see this issue.