Last time I talked about how my development team progressed from having all of our .net code in a single repository with a single solution to using a more modular architecture complete with encapsulated domains.
When we started using this appraoch, we were still limited in a few ways:
- Everyone needs to integrate with the newest code
- Difficult to patch an old version of a dependency
- Cascading failures on the build server
Even though we broke the ProjectReference rats nest, we still had an implicit dependency on various shared code. It all had to be checked out and built in the right order.
Binary Package Management
The next logical step was to further decouple our shared code by packaging it up and publishing those packages. If we could do that, we could decide when to upgrade dependencies on a product by product basis.
There are two package managers in the .net ecosystem: OpenWrap and NuGet.
When we started shopping around, OpenWrap had been around longer and seemed to be a better choice. There’s a comparison of the products on stackoverflow.
We worked with OpenWrap for over 6 months and during that time started to find some problems around integration with Visual Studio and ReSharper. OpenWrap wants to manage dependencies per solution, and we have many cases where we want to control dependencies at a per project level. We also started to notice that NuGet was getting new versions released on a fairly regular schedule, while OpenWrap 2.0 was in unstable beta limbo for over a year.
Around the same time we started playing with Octopus Deploy for deploying our code. Since Octopus uses NuGet packages for deployment, we figured it would make sense to standardize on one package management system for both deployments and dependency management. It’s true that those are separate problem spaces, but having less build scripts is always a good thing.
Thoughts on NuGet
NuGet has several conventions that make it easy to create simple packages that others can reference. You can share assemblies and content easily, and when you want to customize anything there are some powershell extension points you can hook into.
One problem we run into is that when building packages, sometimes there’s a NuGet convention we want to customize or suppress, and often we can’t.
For example, if you create a
nuspec and place it adjacent to a
file, NuGet will look at the project and automatically inject metadata
and content into the package. For some things, you can override this
behavior with explicit specifications in the nuspec, but the behavior
can be surprising and confusing.
NuGet supports the concept of transitive dependencies… sort of. If you install package A, and A depends on package B, NuGet will go find a version of B and install it while installing A. However, NuGet doesn’t do any record keeping to remember that B is a transitive dependency. To your project, A and B appear simply as direct dependencies.
There may be cases where A depends on B at runtime, but consumers of A shouldn’t need to code against B at design time.
There may be other cases where B is an optional dependency for A, and A can be used without it.
Since NuGet doesn’t have a concept of scope, it only has one simplistic approach to dealing with transitive dependencies: treat them just like direct dependencies.
When you ask NuGet to update a specific package, it will first look for
updates to transitive dependencies that the package depends on. This may
seem obvious or desirable to some, but personally I find it confusing.
You can control this behavior with the
-IgnoreDependencies flag in
the Package Management Console, but oddly you don’t get that option
in the command line
nuget.exe or from the Visual Studio GUI Package
Package Feed Performance
We use continuous integration, and every successful build produces “release candidate” versions of packages. We generate 50 to 100 packages a day.
Using the simple NuGet UNC share quickly failed to scale, so next we tried NuGet.Server and found that it doesn’t perform well either.
NuGet Gallery seemed like overkill with its SQL Server requirement, so I started optimizing NuGet.Server. This project ended up taking quite a while, but the good news is that the fruits of the labor are now open source on GitHub at https://github.com/themotleyfool/NuGet.
For more information about that project, see my previous post.
Refactoring Applications and Shared Code
We try to use Semantic Versioning to communicate breaking changes in the packages we publish, so sometimes when we want to use a refactoring tool like Change Method Signature or Use Base Class it would be nice to have application and shared code loaded into a single instance of Visual Studio.
We created a tool called SlimJim that generates these Solution files on the fly.
If you create a Solution with application code and shared library code, ReSharper will be smart enough to apply refactoring tools across the projects even though ProjectReference style references are not being used.
However, Visual Studio won’t know the correct order to build projects in, and won’t automatically copy outputs from shared libraries over to applications.
We extended SlimJim to convert assembly references to project references and back to address this limitation.
In terms of capability and maturity, we’re in a much better place than we were a few years ago. However, we still have a ways to go in terms of productivity and workflow.
NuGet has helped us move in the right direction and we hope to see further enhancements and even contribute some more of our own as we develop them.