Failed to load application: 'module' object has no attribute 'ThreadLocalEngineStrategy'

[ryandesign (Ryan Carsten Schmidt)]

After upgrading ports on the buildmaster for the first time in awhile, buildmaster doesn't start anymore:

/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/OpenSSL/crypto.py:14: CryptographyDeprecationWarning: Python 2 is no longer supported by the Python core team. Support for it is now deprecated in cryptography, and will be removed in the next release.
  from cryptography import utils, x509
:0: UserWarning: You do not have a working installation of the service_identity module: 'No module named service_identity'.  Please install it from <https://pypi.python.org/pypi/service_identity> and make sure all of its dependencies are satisfied.  Without the service_identity module, Twisted can perform only rudimentary TLS client hostname verification.  Many valid certificate/hostname mappings may be rejected.
Unhandled Error
Traceback (most recent call last):
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/twisted/application/app.py", line 674, in run
    runApp(config)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/twisted/scripts/twistd.py", line 25, in runApp
    runner.run()
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/twisted/application/app.py", line 381, in run
    self.application = self.createOrGetApplication()
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/twisted/application/app.py", line 453, in createOrGetApplication
    application = getApplication(self.config, passphrase)
--- <exception caught here> ---
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/twisted/application/app.py", line 464, in getApplication
    application = service.loadApplication(filename, style, passphrase)
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/twisted/application/service.py", line 416, in loadApplication
    application = sob.loadValueFromFile(filename, 'application')
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/twisted/persisted/sob.py", line 177, in loadValueFromFile
    eval(codeObj, d, d)
  File "buildbot.tac", line 4, in <module>
    from buildbot.master import BuildMaster
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/buildbot/master.py", line 38, in <module>
    from buildbot.db import connector
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/buildbot/db/connector.py", line 24, in <module>
    from buildbot.db import enginestrategy
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/buildbot/db/enginestrategy.py", line 62, in <module>
    class BuildbotEngineStrategy(strategies.ThreadLocalEngineStrategy):
exceptions.AttributeError: 'module' object has no attribute 'ThreadLocalEngineStrategy'


Failed to load application: 'module' object has no attribute 'ThreadLocalEngineStrategy'

[ryandesign (Ryan Carsten Schmidt)]

Downgrading py27-sqlalchemy from 1.4.46_0 back to 1.3.23_0 fixed it.

[jmroot (Joshua Root)]

Yeah, I also found that sqlalchemy < 1.4 was needed. See the comments in ​https://github.com/macports/macports-infrastructure/blob/master/buildbot/requirements.txt.

[ryandesign (Ryan Carsten Schmidt)]

py27-sqlalchemy was removed in [1a22cb368938957217a16f9343d6398e91b5ba22/macports-ports] and then re-added in [e7b3b91458780ef07ce9447cf0df41db34464de5/macports-ports] for the benefit of buildbot-0.8 but if that's the only reason it's being kept around it would be more helpful if it were the last version before 1.4.0.

Worked around for the moment by defining my own py27-sqlalchemy port at 1.3.24:

​https://github.com/ryandesign/macports-infrastructure/commit/73c3be5631f232f25e4e371959422b1ffe97ec0f

Or if someone can patch buildbot-0.8 to work with SQLAlchemy 1.4.x that's great too.