Why does dotnet restore on a .sln ignore `DownloadContentFiles` tasks in .csproj projects?

Question

I have an .sln referencing a single .csproj. Inside the .csproj I download static dependencies into ASP.NET's wwwroot:

  <Target Name="DownloadContentFiles" BeforeTargets="Restore">
    <DownloadFile SourceUrl="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" DestinationFolder="$(MSBuildProjectDirectory)/wwwroot/bootstrap/css/">
      <Output TaskParameter="DownloadedFile" ItemName="Content" />
    </DownloadFile>
  </Target>

My production dockerfile attempts to download all deps (including bootstrap) with dotnet restore on the solution file:

FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build

WORKDIR /app
COPY *.sln .
COPY FooProject/*.csproj ./FooProject/

RUN dotnet restore

Unfortunately, only the dotnet deps are downloaded, and my DownloadContentFiles target is ignored. However, if I add

RUN cd FooProject && dotnet restore

to my dockerfile, the file is downloaded as expected. Am I missing something obvious? Shouldn't a dotnet restore on a solution behave like individual restores on the solution's members?

I have checked dotnet restore's documentation, but no options appear to be helpful in this regard.

Answer 1

dotnet restore on a solution does not trigger project-level BeforeTargets="Restore" hooks.

It only triggers a package restore operation, ignoring other custom MSBuild logic.

To run your download logic, invoke restore on the individual project or invoke your custom target explicitly.