[Feature] Impose constraints on the dependency graph via tags

[photomoose]

This functionality already exists but appears to be only implemented by linter plugins to ESLint or TSLint.

We have moved 50+ .NET projects over into a monorepo using nx-dotnet, but we now fear that it might become a monolith/ball of spaghetti if we cannot impose constraints on which apps can depend on which libraries.

Is there a solution for this?

[AgentEnder]

Wow! I'm so glad to hear that you all have adopted nx-dotnet and only had a few small issues so far. If you have a chance, I'd love to hear more about how its went. Here is a discussion thread that would be great for that: #83

There is definitely a path to move forward on supporting nx-enforce-module-boundaries, but the existing rule does only support ESLint / TSLint. Better linting support is something I'd like to implement, but C# code analyzers run at build time rather than being in a separate lint step, which makes it a bit less comparable to something like eslint.

Anyways, the way to handle this would be writing a custom roslyn analyzer and either parsing eslintrc to get module boundaries configuration, or having a section for that in the nx-dotnet config file. I can try to work on this at some point next week, but I do not have personal experience with writing them yet. Should be fun to learn 😄.

The analyzer should be pretty simple, we wouldn't have to iterate over all of the C# files. Should just look something like

1. Parse tags from nx.json
2. Read boundaries either from eslintrc or nx-dotnet config
3. Iterate over project files
   1. For each project reference, check if its an nx-dotnet project.
   2. Check tags, and if they are breaking a boundary
   3. If so, report error on that node in the csproj / vbproj / fsproj xml

If anyone on your team wants to try it out, they can feel free. I'll leave this as up-for-grabs until I take it, but if anyone wants it feel free to assign it to yourself.

[AgentEnder]

@photomoose A roslyn analyzer would give feedback during regular development in the ide, but would a prebuild msbuild task be acceptable for you?

An msbuild task would allow us to reuse existing utilities as we could write it in node.

[photomoose]

@AgentEnder Sure, an msbuild task will probably suffice - we're just looking for something to fail the build essentially - not too fussed about it being reported in the IDE at the moment (although that might be a nice to have).

I'll document our experiences so far in #83 shortly... but at the moment, things are looking promising. I've discovered a few minor issues which I'll either fix or raise issues accordingly.