Question: .NET 6 In-Process Function runs fine on Azure .NET 8 Isolated ?!

Chrissie commented 2 months ago

What version of .NET does your existing project use?

.NET 6

What version of .NET are you attempting to target?

.NET 8

Description

If I build an Azure Function with the In-Process model, on .NET 6, I am able to run it on .NET 8 Isolated in Azure. I don't understand why this works, I thought the Isolated-Worker would not accept existing In-Process Functions? Can someone explain why this works? I can't find any source or reference which states that this should work.

Steps:

Have an existing Azure Function on Azure
Create an empty Azure Function, In-Process, .NET 6.0, Http Trigger in Visual Studio
run dotnet publish -o Publish
Zip deploy using Azure CLI az functionapp deployment source config-zip
Make sure the Azure Function App Configuration has FUNCTIONS_WORKER_RUNTIME with value dotnet-isolated. If not, change it.

Project configuration and dependencies

Empty .NET 6 In-Process Azure Function Project with HttpTrigger

.csproj:

<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFramework>net6.0</TargetFramework>
<AzureFunctionsVersion>v4</AzureFunctionsVersion>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="Microsoft.NET.Sdk.Functions" Version="4.4.0" />
</ItemGroup>
<ItemGroup>
<None Update="host.json">
  <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
</None>
<None Update="local.settings.json">
  <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
  <CopyToPublishDirectory>Never</CopyToPublishDirectory>
</None>
</ItemGroup>
</Project>