External runners are unreliable

The external runners (Migrate.exe, dotnet fm, msbuild) are unreliable due to several problems around different target frameworks (net461, netstandard1.3, netcoreapp2.0, etc.) and .NET implementations (Framework, Core, Mono).

The current implementation is very naive and just tries to load the assemblies and its dependencies into the current context.

Situations

The following situations can be found:

Executed from project directory

This would probably require us to use the same method, which requires the user to specify the startup project and the target project.

The following things are of interest for us:

• Microsoft.EntityFrameworkCore.Design (required by dotnet-ef)
• dotnet-ef

Executed from bin/ directory

This will only work when all dependencies are available, so I suggest that we don’t support this use case.

Executed on published output

Maybe we can use DotNetCorePlugins?

Tools

Every tool should support executing the migrations from the published output and only dotnet-fm and msbuild tasks should support executing migrations from source code.

[jzabroski]

@livarcocc has communicated in https://github.com/microsoft/msbuild/issues/4882 that https://github.com/microsoft/msbuild/issues/1309 will be closed and work will focus on https://github.com/microsoft/msbuild/issues/1754

Overall, this is great news. I requested in https://github.com/microsoft/msbuild/issues/1309 that they support more robust .NET Core CLI Tool scenarios.

[jzabroski]

Couple of thoughts here based on some fast reading today, that I’d like to share. This might not solve our problems, but is in general good to know as it is part of the overall “knobs we can turn”:

1. Forcing all PackageReferences in a .NET SDK project file to be included in the bin directory:
   • Example:

   <CopyLocalLockFileAssemblies>true</CopyLocalLockFileAssemblies>
   

   • Known issues: https://github.com/dotnet/sdk/issues/933 (fixed but not released yet I think)
2. Rick Strahl wrote .NET Core SDK Projects: Controlling Output Folders and Content