use exec to run tailwind binary, so return codes pass through

[blerchin]

We are encountering issues where our CI pipeline can succeed without successfully building Tailwind. It appears this is possible because the TAILWIND_COMPILE_COMMAND is run with system and the return code is never checked. When problems occur, an error is printed to the console but the return code from running rails tailwindcss:build is still 0.

Build errors, such as those caused by a version mismatch between the tailwindcss-rails and the corresponding binary gem, could cause a CI build to fail silently and lead to an unstyled site in production. Therefore I believe it is essential that these rake tasks pass through the return code.

Using Kernel#exec replaces the current process by running the given external command, thereby passing through any return codes. If this is unacceptable, another solution would be to add the exception: true flag to the system call.

[flavorjones]

I just want to note that there's no test coverage on these rake tasks, and I have mild concerns that exec behaves differently on windows than it will on posix-y systems, see for example rubys/sprockets-esbuild#4

If someone can give this a whirl on a Windows machine and comment here I'd feel much more comfortable about it. Or, probably preferably, we should actually exercise these rake tests in the test suite, and I apologize that I don't have the bandwidth to do that work right now.

[blerchin]

I just want to note that there's no test coverage on these rake tasks, and I have mild concerns that exec behaves differently on windows than it will on posix-y systems, see for example rubys/sprockets-esbuild#4

If someone can give this a whirl on a Windows machine and comment here I'd feel much more comfortable about it. Or, probably preferably, we should actually exercise these rake tests in the test suite, and I apologize that I don't have the bandwidth to do that work right now.

That's a fair point, I think I have a windows box I could boot up to confirm this doesn't break anything. As far as testing goes, I'm not sure how valuable it would be unless we have a pipeline to run tests on multiple platforms... these are one-liner rake tasks so we'd basically be testing the Kernel implementation.

[blerchin]

Confirmed that there is no change in behavior when using exec in the rake task.
This is running via cmd with Windows 10.0.19041, Ruby 3.1.2(x64-mingw-ucrt)

[flavorjones]

👍 Thank you for checking!