buildbot.errors.PluginDBError when importing custom www plugin

[p12tic]

Got this error on buildbot.buildbot.net:

checking basedir
checking for running master
checking master.cfg
Errors loading configuration:
  error while parsing config file: 'buildbot_travis.ep' is not a package (traceback in logfile)
Unhandled error in Deferred:

Traceback (most recent call last):
  File "<string>", line 27, in <module>
    
  File "/home/bbuser/workdir/buildbot/master/buildbot/master.py", line 102, in __init__
    self._services_d = self.create_child_services()
  File "/home/bbuser/buildbot_venv/lib/python3.9/site-packages/twisted/internet/defer.py", line 2256, in unwindGenerator
    return _cancellableInlineCallbacks(gen)
  File "/home/bbuser/buildbot_venv/lib/python3.9/site-packages/twisted/internet/defer.py", line 2168, in _cancellableInlineCallbacks
    _inlineCallbacks(None, gen, status, _copy_context())
--- <exception caught here> ---
  File "/home/bbuser/buildbot_venv/lib/python3.9/site-packages/twisted/internet/defer.py", line 2000, in _inlineCallbacks
    result = context.run(gen.send, result)
  File "/home/bbuser/workdir/buildbot/master/buildbot/master.py", line 188, in create_child_services
    self.www = wwwservice.WWWService()
  File "/home/bbuser/workdir/buildbot/master/buildbot/www/service.py", line 198, in __init__
    self.apps = get_plugins('www', None, load_now=True)
  File "/home/bbuser/workdir/buildbot/master/buildbot/plugins/db.py", line 366, in get_plugins
    return _DB.add_namespace(namespace, interface, load_now)
  File "/home/bbuser/workdir/buildbot/master/buildbot/plugins/db.py", line 316, in add_namespace
    tempo.load()
  File "/home/bbuser/workdir/buildbot/master/buildbot/plugins/db.py", line 253, in load
    self._tree.load()
  File "/home/bbuser/workdir/buildbot/master/buildbot/plugins/db.py", line 130, in load
    child.load()
  File "/home/bbuser/workdir/buildbot/master/buildbot/plugins/db.py", line 59, in load
    self._value = self._loader(self._entry)
  File "/home/bbuser/workdir/buildbot/master/buildbot/plugins/db.py", line 231, in _load_entry
    raise PluginDBError(f'Unable to load {self._group}:{entry.name}: {str(e)}') from e
buildbot.errors.PluginDBError: Unable to load buildbot.www:buildbot_travis: 'buildbot_travis.ep' is not a package

[p12tic]

Root cause is that #7270 introduced usage of importlib.resources as a replacement for importlib_resources. The new APIs are more strict with the parameters. The fix is to use __package__ as the first argument to buildbot.www.plugin.Application.

[p12tic]

Fixed in #7305 for builtin buildbot www plugins.

[p12tic]

Fixed in buildbot/buildbot_travis#148 for buildbot_travis.

[yan12125]

Root cause is that #7270 introduced usage of importlib.resources as a replacement for importlib_resources. The new APIs are more strict with the parameters. The fix is to use __package__ as the first argument to buildbot.www.plugin.Application.

Sorry for the breakage. Just to clarify: importlib_resources is generally a "newer" API than importlib.resources. In this case, the restriction for the first argument is relaxed in importlib_resources 5.10.0 [1][2], or importlib.resources as of Python 3.12 [3]. If you want to keep backward compatibility for plugins, you can use:

if sys.version_info[:2] >= (3, 12):
    # TODO: document why 3.12 is needed
    import importlib.resources as importlib_resources
else:
    import importlib_resources

Also, the breakage caused by #7270 is not always fixed only by a simple replacement. In cases where __package__ and __name__ are different, importlib_resources may look into a different path for files after the replacement, and thus plugin developers may need to reorganize the filesystem layout for static assets. This is not an issue for buildbot_travis as buildbot_travis.ep is right below buildbot_travis.

[1] python/importlib_resources#258
[2] https://importlib-resources.readthedocs.io/en/latest/history.html#v5-10-0
[3] https://github.com/python/importlib_resources#compatibility