Which runtime versions are supported without self-contained?

[mpetito]

I have a docker image which uses the latest SDK and lambda/dotnet image and looks something like the following:

FROM public.ecr.aws/lambda/dotnet:6 AS base

FROM mcr.microsoft.com/dotnet/sdk:6.0 as build
WORKDIR /src
# copy csproj and restore...

WORKDIR "/src"
# copy sources

FROM build AS publish
ARG BUILD_CONFIG=Release
RUN dotnet publish "MyProject.csproj" \
    --configuration $BUILD_CONFIG \
    --no-restore \
    --runtime linux-x64 \
    --self-contained false \
    --output /app/publish

FROM base AS final
WORKDIR /var/task
COPY --from=publish /app/publish .

CMD ["MyProject::MyProject.LambdaEntryPoint::FunctionHandlerAsync"]

When the container starts and assuming I publish with --self-contained false, I get the following error because the expected runtime is missing from the lambda image.

A fatal error occurred. The required library libhostfxr.so could not be found.
If this is a self-contained application, that library should exist in [/var/task/].
If this is a framework-dependent application, install the runtime in the global location [/usr/share/dotnet] or use the DOTNET_ROOT environment variable to specify the runtime location or register the runtime location in [/etc/dotnet].

If I inspect the lambda/dotnet image, I see that it has runtime 6.0.1 and when I inspect the dotnet/sdk image I see that it has runtime 6.0.3.

I realize that I could just enable self-contained and it resolves the problem by copying the runtime. I think this effectively the solution proposed by #573. However, this increases the resulting image size by ~100MB and raises a couple questions for me (and perhaps I'm just missing something).

Is there a benefit of using lambda/dotnet:6 as a base image if I have to copy the latest runtime using self-contained? The resulting image now has both 6.0.1 and 6.0.3 runtimes and I'm only using the latter.

Will there be (future) runtime updates for lambda/dotnet:6 or is the intent that it will always be fixed to 6.0.1?

[ganeshnj]

@mpetito thanks for point this out. We had some issue with the docker images publishing internally to https://gallery.ecr.aws/lambda/dotnet which resulted in older version of .NET runtime in the image.

This has been fixed now and I have verified the image now contains the 6.0.4 runtime which is latest available as of now.

└ $ docker run -it --entrypoint bash public.ecr.aws/lambda/dotnet:6
bash-4.2# dotnet --list-runtimes
Microsoft.AspNetCore.App 6.0.4 [/var/lang/bin/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 6.0.4 [/var/lang/bin/shared/Microsoft.NETCore.App]
bash-4.2#

It is recommended to use https://gallery.ecr.aws/lambda/dotnet base image as we regularly patch the images as new .NET runtime updates are available. That said, if you have a use case that requires custom base image, you are free to bring your own.

FYI, .NET 6 images are located at https://github.com/aws/aws-lambda-dotnet/tree/master/LambdaRuntimeDockerfiles/Images/net6

[ganeshnj]

Spoke too soon, 6.0.5 is out. We are working on image update :)

[mpetito]

This is very useful to know, thank you.

I suppose the only issue now is whether I pin the images in my dockerfile to a specific sdk version.

I'd prefer to always use the latest SDK, but the corresponding lambda/dotnet image may not yet be updated, and I can't see an easy way to determine the correct sdk tag once I've pulled the latest lambda/dotnet image.