Allow vcpkg export with manifest-based projects

[morphogencc]

---

Is your feature request related to a problem? Please describe.
I use manifests to track my dependencies and automatically build them in Visual Studio. I've recently started doing Continuous Integration with GitHub Actions, and right now I build all dependencies using vcpkg in the Docker container:

        name: Add MSBuild to PATH
        uses: microsoft/setup-msbuild@v1.0.2

      - name: Install packages and dependencies
        run: |
          bootstrap-vcpkg
          vcpkg install --triplet "x64-windows-static" --x-manifest-root .
          vcpkg integrate install
      - name: Build project
        working-directory: ${{env.GITHUB_WORKSPACE}}
        run: msbuild /m /p:Configuration=${{env.BUILD_CONFIGURATION}} /p:Platform=${{env.BUILD_PLATFORM}} ${{env.SOLUTION_FILE_PATH}}

However, even though my projects only directly use 3-5 dependencies, once those libraries' dependencies are built, vcpkg is responsible for building 50-70 packages. This takes upwards of 90 minutes to build in the docker containers, which is a lot longer than I'd prefer.

NuGet is pretty much built to solve this problem, so I looked into using it with vcpkg's export function to load the built binaries into an archive and load them to GitHub. Unfortunately when I try it:

PS D:\Projects\myProjecct> .\dependencies\vcpkg\vcpkg.exe export --nuget
vcpkg export does not support manifest mode, in order to allow for future design considerations. You may use export in classic mode by running vcpkg outside of a manifest-based project.
Note: Updating vcpkg by rerunning bootstrap-vcpkg may resolve this failure.

Proposed solution
I'd like for vcpkg export to support exporting the binaries for dependencies built with the vcpkg manifest system, just like it works in classic mode. This way I could build a NuGet package, load it to my repository as a package, and then use it for automated testing of my C++ projects.

[autoantwort]

Maybe have a look at https://github.com/microsoft/vcpkg/blob/master/docs/users/binarycaching.md#github-packages

[morphogencc]

that looks really promising -- though it looks like that's just for restoring the package via NuGet and Github Packages, right? I don't believe that example shows how the actually create the binary cache and push it to GitHub Packages.

[michaeltryby]

It would be great if I could specify a package store where my dependencies are cached in the manifest file. This seems obvious, so there must be a reason why it hasn’t been implemented.

[morphogencc]

Agreed; the binary caching mode above would be super helpful it there was also a way to automatically generate the dependencies and store them.

[matthewclendening]

Isn't binary caching on by default? (vcpkg will cache on the local system). If you specified your own cache location(either through the VCPKG_BINARY_SOURCES environment variable or the command line), would that be what you want?

[michaeltryby]

The use case I had in mind was an ephemeral system like a CI workflow. Although I do agree that the current binary cache mechanism works well when building locally.

[autoantwort]

You can also use the binary cache in a ci workflow. There are a lot of supported caching backends.

[michaeltryby]

I have configured binary cache on several CI systems. In my experience it leaves a lot to be desired. It is much easier and straight forward to fetch a package from a binary store.

[AugP]

Revisiting this to add that we have added vcpkg export support for manifest mode in the 2023.10.19 release. See our blog post for details: https://devblogs.microsoft.com/cppblog/vcpkg-2023-10-19-release-export-for-manifests-documentation-improvements-and-more/