Add .NET runtimes

[1davidmichael]

Description

Currently there are not provided docker images for the .NET runtime, and the sam build command does not support the --use-container flag. This makes typical build and deploy workflows with SAM not working consistently for .NET projects. It would be great if a Docker image could be provided and the sam cli updated to work with the container.

Benefits

Ensures consistent behavior for all AWS Lambda supported runtimes by the AWS SAM cli and build/deploy workflow.

Request

Add .NET Dockerfiles supporting AWS runtimes

• Dockerfile-dotnetcore31
• Dockerfile-dotnetcore21

[chrisoverzero]

It's especially confusing that such a container is listed on the ECR Public Gallery, but has no data/tags associated with it.

This makes typical build and deploy workflows with SAM not working consistently for .NET projects.

Even more than consistency, this lack prevents certain optimizations for .NET Lambda Functions. Deploying an application as ReadyToRun helps startup times significantly. To do it, the application has to be built on the deployment target (barring some limited cross-compilation). This is much easier with an official SAM build image.

[mr-davidc]

Will this issue also cover introducing an AWS SAM build image for net5.0 ?

[chrisoverzero]

I do not intend to, at least. net5.0 is not a supported Lambda runtime.

[mr-davidc]

Yea of course @chrisoverzero.

I was thinking perhaps an AW SAM build image for net5.0 would only be for building Lambdas targeting net5.0 with PackageType: Image. Kind of like you can do using the AWS SAM CLI on your local machine.

[ssenchenko]

Image for .NET Core 3.1 merged. Closing this issue.
There are no plans to add .NET Core 2.1 or .NET 5