Support installing multiple versions of .NET Core SxS

[natemcmaster]

I would like to use this action to setup .NET Core for some class libraries I support. I like to run tests on multiple versions of .NET Core, but it appears I cannot use this task to install multiple versions of .NET Core.

Repro

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/setup-dotnet@v1
      with:
        version: '2.1.801'        
    - run: dotnet --info
    - uses: actions/setup-dotnet@v1
      with:
        version: '3.0.100-preview8-013656'
    - run: dotnet --info

Expected

Both .NET Core 2.1 and 3.0 are installed and available when running dotnet commands.

Actual

Usages of actions/setup-dotnet are not additive; the last one wins, so only 3.0.100-preview8-013656 is available.

logs.zip

[damccorm]

This seems like reasonable behavior to me, but I may be missing something - in general, I think I would want the most recent version to win. Also note that after you've installed a version once, setting it back to that version is essentially free since its cached, you just need to run setup-dotnet again with that version.

Am I missing a use case here?

[natemcmaster]

Here is one use case (there are more, but this is the most common). Consider, for instance, a test project file like this:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
     <TargetFrameworks>netcoreapp3.0;netcoreapp2.2;netcoreapp2.1</TargetFrameworks>
  </PropertyGroup>
  <ItemGroup>
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.0.0" />
  </ItemGroup>
</Project>

When you run dotnet test for this project, the test runner will launch tests for the three versions of .NET Core listed, 2.1, 2.2, and 3.0. If only 3.0 is installed, the 2.1 and 2.2 test runs would fail.

The way to make this work is to install all versions of .NET Core into the same root folder.

[natemcmaster]

Elaborating more on on this:

The way to make this work is to install all versions of .NET Core into the same root folder.

.NET Core can have multiple versions installed side by side. Invoking the dotnet executable dispatches to the right version based on the app's configuration. So, with the repro above, I was expecting to see the installation of .NET Core look something like this on disk:

- /opt/tools/dotnet/x64/
    + dotnet                             <--- the main dotnet executable on PATH
    - shared/
        - Microsoft.NETCore.App/
            + 2.1.12/
            + 3.0.0-preview8-28405-07/
        - Microsoft.AspNetCore.App/
            + 2.1.12/
            + 3.0.0-preview8.19405.7/
    - sdk/
        + 2.1.801/
        + 3.0.100-preview8-013656/

The actual layout created by the setup-dotnet action was to install .NET Core into two different locations:

- /opt/hostedtoolcache/dncs/2.1.801/x64/
    + dotnet
    - shared/
        - Microsoft.NETCore.App/
            + 2.1.12/
        - Microsoft.AspNetCore.App/
            + 2.1.12/
    - sdk/
        + 2.1.801/
- /opt/hostedtoolcache/dncs/3.0.100-preview8-013656/x64/
    + dotnet
    - shared/
        - Microsoft.NETCore.App/
            + 3.0.0-preview8-28405-07/
        - Microsoft.AspNetCore.App/
            + 3.0.0-preview8.19405.7/
    - sdk/
        + 3.0.100-preview8-013656/

Both /opt/hostedtoolcache/dncs/3.0.100-preview8-013656/x64/dotnet and /opt/hostedtoolcache/dncs/2.1.801/x64/dotnet are in PATH, but the 3.0 version is listed first so it wins.

[NickCraver]

I just hit this as well. Context: we need to test libs against 2.x and 3.x (same as @natemcmaster) but the install for both doesn't work. Still getting the CI/CD working, but I'm currently jammed up on this issue. If it helps, my log is at: https://github.com/MiniProfiler/dotnet/pull/416/checks?check_run_id=210166603

[daveaglick]

Multiple SDK version support is also important for things like build tooling. For example, Cake requires one version of the SDK but the app being built may require a different version.

[blane-nelson]

I hit this as well. I was able to get around by using the --framework parameter for dotnet, but it makes the yml file more complex, because of having the extra steps to switch the framework back and forth. If this can be changed so that it adds each sdk side by side I think it would be helpful.

[alaatm]

This is also required when a referenced library is explicitly using a different runtime. Having the latest 3.0 and attempting to build the project will cause an error, for example: The specified framework 'Microsoft.NETCore.App', version '2.0.0' was not found. Just got stuck with this issue!

[msmolka]

I have other issue. I have app multitarget: net461, netstandard2, netcoreap3. To build it I need SDK 3. To test netstandard I need SDK 2 for netcoreapp. So for now I'm not able to test it properly for multitarget.

[alaatm]

The following can be used as a workaround until this gets implemented:

  - name: Setup .net core 2.2
    uses: actions/setup-dotnet@v1
    with:
      dotnet-version: 2.2.402

  - name: Setup .net core 3.0
    uses: actions/setup-dotnet@v1
    with:
      dotnet-version: 3.0.100

  - name: .net SxS
    run: |
      rsync -a ${DOTNET_ROOT/3.0.100/2.2.402}/* $DOTNET_ROOT/

[jetersen]

@alaatm thanks for the workaround 🙏