I’ll start with be summary BenPhegan posted to a thread I started on NuGet CodePlex site.

1. Developers are historically used to having a local common library location for all their binary dependencies (ie all hintpaths reference “d:\common” or something similar).
2. Often this library is controlled centrally and xcopy/robocopied to all developers machines to provide commonality of build capability, generally the central copy come from a CI build system.
3. There are a lot of different projects that a developer works on with a lot of dependencies, and it is seen as efficient to have a single copy of these dependencies on disk.
4. Project files are included from multiple solutions at arbitrary locations on disk, resulting in mismatched relative hintpaths when using NuGet.

The problem (not the only one) with shared packages directory is that every project that ever loaded a NuGet package creates a record in repositories.config file. You end up with this file containing lots of these. Also some packages directories might get deleted when a package is removed.

First step: Solution-level repositories.config file

My first approach to an “enterprise” NuGet was to get rid of the repositories.config file that is located under packages directory. All the packages.config files can be discovered by iterating through all projects in the solution:

const string fileName = "packages.config";
foreach (var project in solutionManager.GetProjects())
{
  var projectItem = project.FindProjectItem(fileName);
  if(projectItem == null)
  { 
    continue;
  }

  // we have the packages.config file here
}

But then I thought about it and got the idea that I can make repositories.config file local to a solution, i.e. put it in solution scope. And the best place to put NuGet specific file is the .nuget directory. The entries in config file are added with path relative to solution folder.

Solution
  .nuget
     nuget.config
     nuget.exe
     nuget.targets
     repositories.config
  ProjectA
  ProjectB
  packages.config

Now there’s one repositories.config file for every solution containing the records for every available packages.config. Package files in shared directory can be still deleted when the package in repository is no longer needed (this feature can be turned off and shared repository must be cleared manually).

Vote for it on NuGet!

I tried to avoid big changes in NuGet codebase and I was slowly getting to understand how NuGet internals works. Next step was to force NuGet to use the shared packages repository. I changed some classes (get the settings from registry) to find out the only thing I have to do was to add a node to C:\Users\(your name)\AppData\Roaming\NuGet\NuGet.config configuration file. Don’t forget to remove any repositoryPath from a Nuget.config file under your solution directory if you have one.

<config>
  <add key="repositoryPath" value="path to your repository"/>
</config>

The branch and changset details can be viewed on CodePlex here.

The description of how to build (locally and CI) a solution with project(s) referencing assemblies in a shared local directory will follow.

Related posts:

1. Fix an error in PowerShell script in NuGet package without redeployment
2. NuGet pack error “Assembly outside lib folder”
3. Sharing NuGet repository across multiple solutions II