Sensei does not recompile on change on WSL2

[zigarn]

https://stackoverflow.com/questions/62780245/nodemon-and-webpack-dev-server-hot-reload-not-working-under-wsl-2-after-windows/62790703#62790703

A solution would be to support --watch-poll

[zigarn]

Ping @moreau-nicolas: still relevant? Maybe fixed by #132?

[hgwood]

No, as far as I can tell, because I experience this issue too and it's different.

In #131, webpack was recompiling but the browser did not refresh. Here, webpack does not recompile.

[hgwood]

I should add that this issue is relevant when:

• sensei is run inside a Docker container
• the Docker back-end is WSL2
• the training material folder is a Windows folder (as opposed to a Linux folder)

[zigarn]

So it would be that webpack or docker volume doesn't detect FS changes on Windows FS, not sure we could do anything on that, may be a solution would be simply document this use case and propose a workaround (using Unix FS)?

[hgwood]

The stackoverflow page you linked suggests that the training folder should be moved to the Linux FS or that sensei should support polling like you said. I need to test the polling possibility.

[hgwood]

Here's how Next does it: vercel/next.js#302

[hgwood]

I've found a fix and committed it to the watch_poll branch. It's stacked on top of #136 so waiting on #136 to merge before opening a PR.

[moreau-nicolas]

On sensei latest version I do not have the problem : Webpack recompiles, and the browser refreshes. I'm using VS Code with the WSL extension, running sensei from a WSL2 prompt, and launching Code from WSL2 too.

It seems it works better if Code is started after webpack (from another console tab).

[hgwood]

Interesting. Is the working directory part of the Windows FS or the WSL FS? Also, was sensei installed from Windows or from WSL?

[moreau-nicolas]

The working directory is within the Windows FS, accessed through WSL via Ubuntu bash (/mnt/c/Users/Nicolas/...).
Sensei is a bash alias within WSL2.
Hope this helps.
We can arrange a call if needed.

[zigarn]

I tested multiple combinations with WSL2 (not WSL1, may differ in term of FS handling from what I found):

Docker or native	Filesystem	Environment	Command	Result
Docker	Windows	Windows	docker container run --pull always --interactive --tty --rm --volume //c/Users/alex/training-template:/training-template --workdir //training-template --publish 8080:8080 --env SENSEI_PORT --cap-add=SYS_ADMIN zenika/sensei	No reload
Docker	Windows	WSL	docker container run --pull always --interactive --tty --rm --volume //mnt/c/Users/alex/training-template:/training-template --workdir //training-template --publish 8080:8080 --env SENSEI_PORT --cap-add=SYS_ADMIN zenika/sensei	No reload
Docker	WSL	WSL	docker container run --pull always --interactive --tty --rm --volume /home/alex/training-template:/training-template --workdir /training-template --publish 8080:8080 --env SENSEI_PORT --cap-add=SYS_ADMIN zenika/sensei	Reload
Native	Windows	Windows	sensei serve C:/Users/alex/training-template	Reload
Native	Windows	WSL	sensei serve /mnt/c/Users/alex/training-template	Watchpack Error (initial scan): Error: EACCESS: permission denied, lstat '/mnt/c/pagefile.sys'
Native	WSL	WSL	sensei serve /home/alex/training-template	Reload
Native	WSL (network device)	Windows	sensei serve //wsl.localhost/Ubuntu/home/alex/training-template	CMD.EXE was started with the above path as the current directory. UNC paths are not supported. Defaulting to Window directory. Then errors because not in right folder so no slides.json
Native	WSL (drive)	Windows	net use U: //wsl.localhost/Ubuntu; sensei serve U:/home/alex/training-template	fatal: detected dubious ownership in repository at '//wsl.localhost/Ubuntu/home/alex/training-template'
Native	WSL (drive, git safe)	Windows	net use U: //wsl.localhost/Ubuntu ; git config --global --add safe.directory '*' ; sensei serve U:/home/alex/training-template	Errors about handling "c:" URIs, and paths in "C:Usersalex" (without \ nor /)

Tested 344959c (need rebase) and it does solve the problem if we don't forgot to set SENSEI_WATCH_POLL=true.

But Docker WSL2 best practices state that best option is to have the code in WSL FS, mount it directly in docker container and access it through \\wsl$ on Windows side.
Maybe the best option for sensei is to simply update the README.md to advise this solution? WDYT @hgwood @moreau-nicolas?

[hgwood]

Yes I think it's a good idea. We can still add SENSEI_WATCH_POLL later and change the readme to reflect.