[Apple M1 Docker] (_rust_notify.WatchfilesRustInternalError: Error creating watcher: Function not implemented (os error 38))

[thmsrmbld]

Hey Adam,

Thanks for this lib - looks very useful - unfortunately I wanted to fold it into a platform I work on and I got an error that might raise its head for other users - but it's not an implementation issue on your side, more a general 'Apple M1 Docker Stuff' observation that I suspect will eventually be addressed somewhere far away from this library

In short, I think that watchfiles itself craps out on Dockerised environments that are running on Apple's M1 Silicon.

I installed the library and rebuilt my Docker containers, but got a 502 bringing the development server up. I ran docker logs for the container and it gave me the following traceback:

Traceback (most recent call last):
  File "/app/manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/lib/python3.10/dist-packages/django/core/management/__init__.py", line 446, in execute_from_command_line
    utility.execute()
  File "/usr/lib/python3.10/dist-packages/django/core/management/__init__.py", line 440, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/lib/python3.10/dist-packages/django/core/management/base.py", line 414, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/usr/lib/python3.10/dist-packages/django/core/management/commands/runserver.py", line 74, in execute
    super().execute(*args, **options)
  File "/usr/lib/python3.10/dist-packages/django/core/management/base.py", line 460, in execute
    output = self.handle(*args, **options)
  File "/usr/lib/python3.10/dist-packages/django/core/management/commands/runserver.py", line 111, in handle
    self.run(**options)
  File "/usr/lib/python3.10/dist-packages/django/core/management/commands/runserver.py", line 118, in run
    autoreload.run_with_reloader(self.inner_run, **options)
  File "/usr/lib/python3.10/dist-packages/django/utils/autoreload.py", line 680, in run_with_reloader
    start_django(reloader, main_func, *args, **kwargs)
  File "/usr/lib/python3.10/dist-packages/django/utils/autoreload.py", line 661, in start_django
    reloader.run(django_main_thread)
  File "/usr/lib/python3.10/dist-packages/django/utils/autoreload.py", line 344, in run
    self.run_loop()
  File "/usr/lib/python3.10/dist-packages/django/utils/autoreload.py", line 350, in run_loop
    next(ticker)
  File "/usr/lib/python3.10/dist-packages/django_watchfiles/__init__.py", line 21, in tick
    for file_changes in watcher:
  File "/usr/lib/python3.10/dist-packages/watchfiles/main.py", line 85, in watch
    watcher = RustNotify([str(p) for p in paths], debug)
_rust_notify.WatchfilesRustInternalError: Error creating watcher: Function not implemented (os error 38)

The pertinent part of this seems to be:

  File "/usr/lib/python3.10/dist-packages/watchfiles/main.py", line 85, in watch
    watcher = RustNotify([str(p) for p in paths], debug)
_rust_notify.WatchfilesRustInternalError: Error creating watcher: Function not implemented (os error 38)

Which basically notes that in watchfiles, we're failing here.

This os error, I think is basically not to do with your implementation at all - this error seems quite frequent in other libraries when running certain code in Dockerised environments on Apple's M1 Silicon:

• "Function not implemented" error on Mac M1, works on Ubuntu  Azure/azure-functions-core-tools#2901
• Heed error: Function not implemented (os error 38) meilisearch/meilisearch#1195

For what it's worth there are zero actions / fixes to take here - it's more for if people on the newer machines running Dockerised environments run into this, that there's a record that this can happen. There is discussion that rebuilding your Docker images to use multi-arch images can solve this, but this is not a problem for this library itself.

It is possible this could also be useful report in watchfiles itself, I just logged it here because this is the lib that I used to invoke it.

Give me a shout if anything's unclear on this - just hoping to help someone else if they wander through asking. :)

[adamchainz]

Report upstream

[adamchainz]

Also share your dockerfile... At a guess, are you using alpine linux? It has so many limitations, it may simply not have the file watching functions available. I know it makes other things worse and should generally be avoided.

[Chadys]

Fixed recently by watchfile: samuelcolvin/watchfiles#167

[adamchainz]

Thanks for the update @Chadys