[tahoe-lafs-trac-stream] [Tahoe-LAFS] #3259: The switch to use pkg_resources breaks frozen builds

[Tahoe-LAFS]

#3259: The switch to use pkg_resources breaks frozen builds
------------------------+------------------------
 Reporter:  cypher      |          Owner:  daira
     Type:  defect      |         Status:  new
 Priority:  normal      |      Milestone:  1.14.0
Component:  packaging   |        Version:  n/a
 Keywords:  regression  |  Launchpad Bug:
------------------------+------------------------
 [https://github.com/tahoe-lafs/tahoe-lafs/pull/646 PR #646] introduced a
 change that broke "frozen" builds of Tahoe-LAFS (i.e., standalone
 executables generated by PyInstaller, cx_Freeze, and the like).
 Specifically, because "frozen" python interpreters run outside of and
 without a traditional setuptools-based packaging environment, the
 [https://github.com/tahoe-lafs/tahoe-
 lafs/blob/eb751baeef935f02bbdc1b1ed7ce8774d5e47be1/src/allmydata/version_checks.py#L29
 pkg_resources.get_distribution(__appname__)] call will fail as follows
 when running under a "frozen" interpreter:

 {{{
 Traceback (most recent call last):
   File "tahoe.py", line 23, in <module>
     from twisted.python.procutils import which
   File "/tmp/pip-install-
 Om4he9/pyinstaller/PyInstaller/loader/pyimod03_importers.py", line 395, in
 load_module
   File "site-packages/allmydata/scripts/runner.py", line 9, in <module>
   File "/tmp/pip-install-
 Om4he9/pyinstaller/PyInstaller/loader/pyimod03_importers.py", line 395, in
 load_module
   File "site-packages/allmydata/version_checks.py", line 29, in <module>
   File "site-packages/pkg_resources/__init__.py", line 481, in
 get_distribution
   File "site-packages/pkg_resources/__init__.py", line 357, in
 get_provider
   File "site-packages/pkg_resources/__init__.py", line 900, in require
   File "site-packages/pkg_resources/__init__.py", line 786, in resolve
 pkg_resources.DistributionNotFound: The 'tahoe-lafs' distribution was not
 found and is required by the application
 [23457] Failed to execute script tahoe
 }}}

 Conditionally skipping this call when running under a frozen interpreter
 will allow the execution of the application to continue as intended (as is
 already being done elsewhere in the `version_checks` module -- e.g.,
 [https://github.com/tahoe-lafs/tahoe-
 lafs/blob/eb751baeef935f02bbdc1b1ed7ce8774d5e47be1/src/allmydata/version_checks.py#L324
 here]).

--
Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3259>
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