Query regarding potential introduction of lower versioned frameworks in dotnet runtime containers

[shantanoo-desai]

Query Description

• I have a bunch of already compiled .dll files and do not have the source files for a project that I wish to containerize.
• The ASP.NET runtime required for this application is v6.0.0

Caveat

There are certain .dll binaries where they require backwards compatible v5.0.0 framework to run things successfully.

Trial

My current Dockerfile is the following:

FROM mcr.microsoft.com/dotnet/aspnet:6.0-focal

RUN mkdir -p /usr/share/App/icon.NExT
COPY ./sku.key /usr/share/App/icon.NExT/

COPY ./appsettings.json /icon/DeployServer-Files/

WORKDIR /icon

COPY ./* /icon/DeployServer-Files/
CMD [ "dotnet", "DeployServer-Files/DeployServer.dll" ]

which brings up the server based on some Kestrel configuration I provide in the appsettings.json file. Upon triggering some specific workflow on a dedicated HTTP API I keep getting the following logs:

                         | The specified framework can be found at:
icon42test        | It was not possible to find any compatible framework version
icon42test        | The framework 'Microsoft.AspNetCore.App', version '5.0.0' (x64) was not found.
icon42test        |   - The following frameworks were found:
icon42test        |       6.0.6 at [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
icon42test        | 
icon42test        | You can resolve the problem by installing the specified framework and/or SDK.

I understand the distinction of having separation of different runtimes/frameworks/sdks but would there be some form of documentation as to provide lower versioned framework/sdk into the current runtime?

[richlander]

Here's an easy pattern to copy other runtimes into your container image.

https://github.com/octokit/octokit.net/blob/main/.devcontainer/Dockerfile#L8-L9

That example is copying the SDK. You don't want that. You'd want:

COPY --from=mcr.microsoft.com/dotnet/aspnet:5.0-focal /usr/share/dotnet/shared /usr/share/dotnet/shared

I switch to pulling Ubuntu 20.04. This way, you only pull the OS once.

.NET 5 is now out of support, however.

[shantanoo-desai]

Thank you. I just found the solution exactly as you mentioned a few minutes ago. I was able to pull two different SDKs into the runtime container and cross-checked it using dotnet --list-sdks and dotnet --list-runtimes. For posterity my Answer on StackOverflow query

[richlander]

Excellent. Glad that your problem is now solved.

I switch to pulling Ubuntu 20.04. This way, you only pull the OS once.

I just realized that while this was good thinking on my part, it doesn't actually apply here. We've stopped updating the .NET 5 images, so the OS layer won't actually match. You will be pulling Ubuntu twice. There isn't a way to avoid that using this technique.