Papercut - add support for `--arch` in dotnet ef migrations bundle

[moozzyk]

TL;DR;
Add support for the --arch argument to dotnet ef migrations bundle for parity with dotnet restore and dotnet publish

I am trying to dockerize my ASP.Net Core application. I plan to build Docker images for different operating systems (mostly linux-64 and linux-arm) from a single Dockerfile. The application uses EF to work with a database. To be able to update my database I create a migrations bundle when building the image.

To prepare the application I can just pass the --arch to dotnet restore or dotnet publish commands like this:

FROM --platform=$BUILDPLATFORM mcr.microsoft.com/dotnet/sdk:8.0 AS build
ARG TARGETARCH
WORKDIR /source
COPY *.csproj .
RUN dotnet restore -a $TARGETARCH
COPY . .
RUN dotnet publish -a $TARGETARCH -o /demo --self-contained

This doesn't work for dotnet ef migrations bundle as it doesn't support the --arch argument. I found that it is possible to achieve the same result by using the --target-runtime parameter that takes a RID. The RID can be created just by stitching OS and ARCH similarly to how dotnet tooling does it:

ARG TARGETOS
dotnet ef migrations bundle --target-runtime $TARGETOS-$TARGETARCH -c ApplicationDbContext -o /demo/app-migrations --self-contained

This works but is cumbersome as it introduces one more concept (RID) to the Dockerfile. It would be nice if dotnet ef migrations bundle also supported the --arch parameter.

One interesting nuance is that the dotnet publish and restore commands support -a as a shortcut for --arch but in dotnet ef migrations bundle -a is already reserved for --assembly

[ajcvickers]

@moozzyk Great to hear from you!