ignore_permission_denied

[earshinov]

There is no reason to stop Django process and exit with error when watch encounters an incident such as an unreadable file, "permission denied" etc. So it seems reasonable to me to always pass ignore_permission_denied=True to watchfiles.

See also samuelcolvin/watchfiles#224, where this flag was introduced.

[earshinov]

Unfortunately, simply passing ignore_permission_denied was not enough to ignore errors in our use case, so I

• enhanced this PR with a try..except to catch exceptions, log and ignore those
• filed an issue to watchfiles so that errors are ignored on their side

You can find a full description of the problem we are facing in the watchfiles issue.

With this try..except, I see exceptions finally being ignored (instead of crashing our Dajngo app):

[WARNING] [2024-03-28 09:49:58] [/usr/local/lib/python3.10/site-packages/django_watchfiles/__init__.py::watch_safely (line 43)]: error in underlying watcher: IO error for operation on /opt/project/.mypy_cache/3.10/grt_helpers/django/validators/__init__.data.json.185fc872ae08f752: No such file or directory (os error 2) about ["/opt/project/.mypy_cache/3.10/grt_helpers/django/validators/__init__.data.json.185fc872ae08f752"]
  Traceback (most recent call last):
    File "/usr/local/lib/python3.10/site-packages/django_watchfiles/__init__.py", line 37, in watch_safely
      yield from f()
    File "/usr/local/lib/python3.10/site-packages/watchfiles/main.py", line 122, in watch
      raw_changes = watcher.watch(debounce, step, rust_timeout, stop_event)
  _rust_notify.WatchfilesRustInternalError: error in underlying watcher: IO error for operation on /opt/project/.mypy_cache/3.10/grt_helpers/django/validators/__init__.data.json.185fc872ae08f752: No such file or directory (os error 2) about ["/opt/project/.mypy_cache/3.10/grt_helpers/django/validators/__init__.data.json.185fc872ae08f752"]
[WARNING] [2024-03-28 09:50:25] [/usr/local/lib/python3.10/site-packages/django_watchfiles/__init__.py::watch_safely (line 43)]: error in underlying watcher: IO error for operation on /opt/project/.mypy_cache/3.10/sentry_sdk/session.data.json.9ab62077a5ffd0bb: No such file or directory (os error 2) about ["/opt/project/.mypy_cache/3.10/sentry_sdk/session.data.json.9ab62077a5ffd0bb"]
  Traceback (most recent call last):
    File "/usr/local/lib/python3.10/site-packages/django_watchfiles/__init__.py", line 37, in watch_safely
      yield from f()
    File "/usr/local/lib/python3.10/site-packages/watchfiles/main.py", line 122, in watch
      raw_changes = watcher.watch(debounce, step, rust_timeout, stop_event)
  _rust_notify.WatchfilesRustInternalError: error in underlying watcher: IO error for operation on /opt/project/.mypy_cache/3.10/sentry_sdk/session.data.json.9ab62077a5ffd0bb: No such file or directory (os error 2) about ["/opt/project/.mypy_cache/3.10/sentry_sdk/session.data.json.9ab62077a5ffd0bb"]

[earshinov]

All references at a glance:

• ignore_permission_denied by earshinov · Pull Request #80 · adamchainz/django-watchfiles
• Ignore error_handler errors under ignore_permission_denied = True? · Issue #266 · samuelcolvin/watchfiles
• PollWatcher: Ignore IO "file not found" exceptions when accessing entry metadata?🥺 · Issue #581 · notify-rs/notify

[adamchainz]

You wrote on the watchfiles issue:

For the moment, I am not ready to tinker with Rust, so I made a PR into django-watchfiles to circumvent this on the outside. But really, I think that this code should be unnecessary and the errors should be ignored right in watchfiles.

Let’s wait and see what Samuel replies.

[earshinov]

@adamchainz , Hey Adam! There's been no reply in my PR to watchfiles for a month. Do you think you could now consider merging this PR into django-watchfiles? If my PR is merged into watchfiles, I can volunteer to update django-watchfiles again to remove the workarounds which we add here in this PR.

[adamchainz]

Samuel has been busy launching Pydantic Logfire: https://pydantic.dev/ . I would still wait for a reply there.

Until then you can install your fork, if you're not already: https://adamj.eu/tech/2019/03/11/pip-install-from-a-git-repository/

I would rather not merge any workarounds here. django-watchfiles is still alpha and I'd rather only add things we're sure we need, to iterate towards a 1.0.0 release.