Function worker's service provider resolves scoped service from the root as singleton

[aventus13]

System version

Framework version: .Net 8.0
Package causing the problem: Microsoft.Azure.Functions.Worker, v1.20.1

Description

In ASP Core web application runtime, trying to resolve a scoped service from a non-scoped (root) service provider throws an error with the following message:

Cannot resolve scoped service from root provider

However, using an instance of IHost built by HostBuilder from Microsoft.Extensions.Hosting doesn't seem to respect service lifetime registration. This can be easily reproduced with the below code. It seems like a bug because the service resolution behavior isn't consistent and can lead to tricky bugs with dependencies relying on scoped context.

Expected behavior

An exception is thrown when resolving a scoped service from a root provider.

Actual behavior

The service is resolved as a singleton.

Code to reproduce

csproj file

<Project Sdk="Microsoft.NET.Sdk">

    <PropertyGroup>
        <OutputType>Exe</OutputType>
        <TargetFramework>net8.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
        <Nullable>enable</Nullable>
    </PropertyGroup>

    <ItemGroup>
        <PackageReference Include="Microsoft.Azure.Functions.Worker" Version="1.20.1"/>
        <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="8.0.0"/>
    </ItemGroup>

</Project>

code

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

var builder = new HostBuilder()
    .ConfigureFunctionsWorkerDefaults();

builder.ConfigureServices((_, services) => services.AddScoped<IDependency, DependencyImplementation>());

var host = builder.Build();
var depOne = host.Services.GetRequiredService<IDependency>();// Expected to get exception here but it resolved the service
var depTwo = host.Services.GetRequiredService<IDependency>();
var areEqual = depOne == depTwo;// true, received same instance

var scopedDepOne = host.Services.CreateScope().ServiceProvider.GetRequiredService<IDependency>();
var scopedDepTwo = host.Services.CreateScope().ServiceProvider.GetRequiredService<IDependency>();
areEqual = scopedDepOne == scopedDepTwo;// false, received scoped instances as expected

Console.ReadKey();

interface IDependency
{ }

class DependencyImplementation : IDependency
{ }

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Issue Details

---

System version

Framework version: .Net 8.0
Package causing the problem: Microsoft.Azure.Functions.Worker, v1.20.1

Description

In ASP Core web application runtime, trying to resolve a scoped service from a non-scoped (root) service provider throws an error with the following message:

Cannot resolve scoped service from root provider

However, using an instance of IHost built by HostBuilder from Microsoft.Extensions.Hosting doesn't seem to respect service lifetime registration. This can be easily reproduced with the below code. It seems like a bug because the service resolution behavior isn't consistent and can lead to tricky bugs with dependencies relying on scoped context.

Expected behavior

An exception is thrown when resolving a scoped service from a root provider.

Actual behavior

The service is resolved as a singleton.

Code to reproduce

csproj file

<Project Sdk="Microsoft.NET.Sdk">

    <PropertyGroup>
        <OutputType>Exe</OutputType>
        <TargetFramework>net8.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
        <Nullable>enable</Nullable>
    </PropertyGroup>

    <ItemGroup>
        <PackageReference Include="Microsoft.Azure.Functions.Worker" Version="1.20.1"/>
        <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="8.0.0"/>
    </ItemGroup>

</Project>

code

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

var builder = new HostBuilder()
    .ConfigureFunctionsWorkerDefaults();

builder.ConfigureServices((_, services) => services.AddScoped<IDependency, DependencyImplementation>());

var host = builder.Build();
var depOne = host.Services.GetRequiredService<IDependency>();// Expected to get exception here but it resolved the service
var depTwo = host.Services.GetRequiredService<IDependency>();
var areEqual = depOne == depTwo;// true, received same instance

var scopedDepOne = host.Services.CreateScope().ServiceProvider.GetRequiredService<IDependency>();
var scopedDepTwo = host.Services.CreateScope().ServiceProvider.GetRequiredService<IDependency>();
areEqual = scopedDepOne == scopedDepTwo;// false, received scoped instances as expected

Console.ReadKey();

interface IDependency
{ }

class DependencyImplementation : IDependency
{ }

Author:	aventus13
Assignees:	-
Labels:	area-Extensions-DependencyInjection
Milestone:	-

[wcsanders1]

@aventus13 It looks like this failure to validate the scope is a result of calling the HostBuilder constructor rather than the CreateDefaultBuilder method, which enables scope validation when the environment is Development: https://github.com/dotnet/runtime/blob/main/src/libraries/Microsoft.Extensions.Hosting/src/HostingHostBuilderExtensions.cs#L327

[aventus13]

Thanks for your response, @wcsanders1. However- apologies if it's slightly off topic- isn't this a symptom of a rather wider problem stemming from the design of the DI's default behaviour? Given that scope validation is not enabled by default, it's possible to run into a tricky and potentially dangerous scenario, i.e. resolving a singleton service that takes in a scoped dependency.

var services = new ServiceCollection();
services.AddSingleton<ISingletonDependency, SingletonDependencyImplementation>()
  .AddScoped<IScopedDependency, ScopedDependencyImplementation>();

var provider = services.BuildServiceProvider()
  .CreateScope()
  .ServiceProvider;

var singleton = provider.GetRequiredService<ISingletonDependency>(); // Resolves successfully with an injected scoped dependency

class SingletonDependencyImplementation : ISingletonDependency
{
  // This should never happen
  public SingletonDependencyImplementation(IScopedDependency scoped)
  {
    // ...
  }
}

[wcsanders1]

I agree @aventus13 that it seems like such behavior would never be wanted. I plan to submit a PR to fix it within this week.

[wcsanders1]

I think #99199 should resolve this.

[steveharter]

It seems like a bug because the service resolution behavior isn't consistent and can lead to tricky bugs with dependencies relying on scoped context.

Yes thanks. This is a common issue; work done here to prevent scoped services from being used with a singleton constructor is good as long as it doesn't significantly affect perf in non-development runtime scenarios. As mentioned above, we do try to do error checking but only in development mode: https://github.com/dotnet/runtime/blob/main/src/libraries/Microsoft.Extensions.Hosting/src/HostingHostBuilderExtensions.cs#L330-L331

[buyaa-n]

I think #99199 should resolve this.

Closing