[WSL2] File changes made by Windows apps on Windows filesystem don't trigger notifications for Linux apps

[SteveSandersonMS]

WSL2 is really close to being a perfect runtime environment for server apps being developed in Windows. Great job! One missing feature however is breaking a core part of the developer flow.

For sources stored on the Windows filesystem, any changes made by Windows applications such as Visual Studio do not trigger any file change notifications as far as Linux apps are concerned. This means that all "live rebuild"-type tools don't work (examples: webpack --watch, jekyll --interactive, and Tilt.dev) when running under WSL2. This unfortunately renders many modern dev workflows unviable.

Notes:

• I strongly expect this is already a known issue as hinted here. However I was unable to find any open GitHub issue that specifically tracks this. Unable to save file when inotify is in use (using Node) #1956 is about a different scenario, File contents differs on mounted Windows drive between Windows and WSL #4064 isn't specifically about change notifications, [WSL 2] File watchers like create-react-app, gulp or sass doesn't work #4224 is closed, WSL2 Increase the maximum amount of inotify user watches #4293 doesn't fix it.
• I'm aware the WSL team suggests that with WSL2 it's good to store your application sources inside the Linux filesystem instead of the Windows one. However I don't think that's a viable solution since the whole point of WSL (for me) is to be able to use Windows-based editors such as full VS with a Linux dev environment. If it was sufficient to use Linux-based editors, I'd just use Mac/Linux as my actual OS and would have no need for WSL.
• This did work great on WSL1
• Changing fs.inotify.max_user_watches doesn't affect this, since the issue is about changes originating on the Windows side.

Bug report template

• Your Windows build number: 10.0.19033.1

• What you're doing and what's happening:

  This applies to all tools that listen for file change notifications, but as an example take webpack. Repro steps:

  • In your Windows filesystem, create an empty directory (example: c:\repro), and then add these three files to it
  • In a WSL2 Ubuntu 18.04 environment, install Node and NPM: sudo apt-get install nodejs npm
  • Still in WSL2, go into the directory from earlier: cd /mnt/c/repro
  • Restore NPM dependencies: npm i
  • Run Webpack in watch mode: npm run build:watch. Wait a few seconds until it completes the first build. It will now be waiting for further changes to your source files.
  • In a Windows application (e.g., Notepad or Visual Studio), open c:\repro\index.js and save some change to it. For example, change 'Hello, world' to 'Hello, world 2'.

• What's wrong / what should be happening instead:

  Expected behavior: Webpack should see the change and rebuild. That is, you'll see it log information about another build, and the output in dist/bundle.js will be updated.

  Actual behavior: Webpack doesn't respond at all, because there's no file change notification.

Finally I understand that the fix for this is likely to be "add file watch capabilities to the Plan9 server", and you may feel this is already being tracked by #4064. However #4064 describes a more obscure symptom of this missing feature and makes it sound like an intermittent issue. What I'm reporting here is not intermittent at all, and is a pretty mainstream scenario (using tools like webpack --watch). Thanks!

[therealkenc]

Yes, #4064 is most unfortunately titled. Worse, the OP has no repro steps and an unecessary symlink confusing the direction they are talking about. Craig's notepad.exe repro with cat isn't an inotify(7) (file watcher) problem, even if implementing inotify is the fix to whatever loosly implied sync problems are going on over there.

Nevertheless #4701 got closed as a dupe with (quoth):

We need to add file watch capabilities to the Plan9 server that serves files to a WSL2 distro, and we're tracking that work item here

So, best I can tell, #4064 is being treated as the LZ for inotify triggers from Windows to WSL2. For lack. #4169 is pretty much exactly your use-case also landed dupe #4064.

This did work great on WSL1

Yes, known regress.

[nake89]

Is there a temporary fix to this? This is giving me a headache.

Using Windows 10, WSL 2. Running npm run serve on my Vue project, which normally hot reloads when I do changes (on my Linux and Mac, and WSL1 and I think maybe WSL2 before(?)). Now I have to shut down and restart the Vue server.

Will probably just install Linux on this machine. Developing on a Windows machine is a real pain.

[craigloewen-msft]

@nake89 are you able to move your project over to the Linux root file system? i.e: Store in your Linux home folder for example? Are there any factors that are blocking you from doing so?

And per @therealkenc 's comment this would be a much better landing zone for adding inotify to the 9P file server. I'll update my comment in #4701 to point here, and add some tags to this issue.

[nake89]

@craigloewen-msft Thanks for messaging me back! I actually solved my issue by moving my project to the linux filesystem in WSL and have had no problems so far. I suggest doing the same. In VS Code simply type ctrl-shift-p and then type "Remote-WSL: New Window" This lets users use the linux filesystem in vs code, for those that did not know this :)

[SteveSandersonMS]

@nake89 That's great if your scenario allows it. But just to clarify for anyone else reading, that's not a solution in general as it doesn't work for other Windows-based editors such as VS.

[craigloewen-msft]

@SteveSandersonMS agreed, we will still be tracking this issue here. :)

Hi, I am encountering this with docker-sync. My setup is:

• working folder under C:\users for various php projects
• Edit a file in phpstorm
• Changes reflected within my WSL2 Ubuntu instance
• Running docker containers within WSL2 with volumes synced using docker-sync and Unison

If I make a change to a file directly inside Ubuntu, changes are reflected in the container's mounted volume. However, if I edit a file in PhpStorm in Windows, the change is reflected in Ubuntu as expected but not in the container.

I can't easily move my files to the Linux filesystem because I need to use PhpStorm and other Windows tools in my dev environment, and I also have other stuff such as Google drive sync running to back up local changes. So the workaround doesn't work for me.

[Carl-Hugo]

@craigloewen-msft Thanks for messaging me back! I actually solved my issue by moving my project to the linux filesystem in WSL and have had no problems so far. I suggest doing the same. In VS Code simply type ctrl-shift-p and then type "Remote-WSL: New Window" This lets users use the linux filesystem in vs code, for those that did not know this :)

This is a great workaround that will save me lots of time until WSL2 supports this use-case. Thanks for sharing!

[Carl-Hugo]

@craigloewen-msft Thanks for messaging me back! I actually solved my issue by moving my project to the linux filesystem in WSL and have had no problems so far. I suggest doing the same. In VS Code simply type ctrl-shift-p and then type "Remote-WSL: New Window" This lets users use the linux filesystem in vs code, for those that did not know this :)

This is a great workaround that will save me lots of time until WSL2 supports this use-case. Thanks for sharing!

I wrote a small blog post explaining this workaround and talking about a few more things that I discovered/experienced, using Jekyll on WSL2: Speed up your builds to up to 375% and watch for changes for an even faster dev cycle using this workaround on WSL2/Ubuntu, if that can help someone.

Note: that applies to more than just Jekyll, Jekyll it was just the catalyst.