Python os.environ throws key error?

Question

I'm accessing an environment variable in a script with os.environ.get and it's throwing a KeyError. It doesn't throw the error from the Python prompt. This is running on OS X 10.11.6, and is Python 2.7.10.

What is going on?

$ python score.py Traceback (most recent call last):   File "score.py", line 4, in <module>     setup_logging()   File "/score/log.py", line 29, in setup_logging     config = get_config()   File "/score/log.py", line 11, in get_config     environment = os.environ.get('NODE_ENV')   File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/UserDict.py", line 23, in __getitem__     raise KeyError(key) KeyError: 'NODE_ENV' $ python -c "import os; os.environ.get('NODE_ENV')" $ 

As requested, here's the source code for score.py

from __future__ import print_function  from log import get_logger, setup_logging setup_logging() log = get_logger('score') 

And here's log.py

import json import os import sys  from iron_worker import IronWorker from logbook import Logger, Processor, NestedSetup, StderrHandler, SyslogHandler  IRON_IO_TASK_ID = IronWorker.task_id()  def get_config():   environment = os.environ.get('NODE_ENV')   if environment == 'production':     filename = '../config/config-production.json'   elif environment == 'integration':     filename = '../config/config-integration.json'   else:     filename = '../config/config-dev.json'    with open(filename) as f:     return json.load(f)  def setup_logging():   # This defines a remote Syslog handler   # This will include the TASK ID, if defined   app_name = 'scoreworker'   if IRON_IO_TASK_ID:     app_name += '-' + IRON_IO_TASK_ID    config = get_config()    default_log_handler = NestedSetup([     StderrHandler(),     SyslogHandler(       app_name,       address = (config['host'], config['port']),       level = 'ERROR',       bubble = True     )   ])   default_log_handler.push_application()  def get_logger(name):   return Logger(name) 

Answer 1

Try running:

find . -name \*.pyc -delete 

To delete your .pyc files.

Researching your problem I came across this question, where a user was experiencing the same thing: .get() seemingly raising a KeyError. In that case, it was caused, according to this accepted answer, by a .pyc file which contained code where a dict value was being accessed by key (i.e., mydict['potentially_nonexistent_key']), while the traceback was showing the code from the updated .py file where .get() was used. I have never heard of this happening, where the traceback references current code from a .py file, but shows an error raised by an outdated .pyc file, but it seems to have happened at least once in the history of Python...

It is a long shot, but worth a try I thought.