Add warning messages to logs if StackStorm running with python 2

Author: amanda11

st2common/st2common/constants/error_messages.py

@@ -15,7 +15,8 @@
 
 __all__ = [
     'PACK_VIRTUALENV_DOESNT_EXIST',
-    'PACK_VIRTUALENV_USES_PYTHON3'
+    'PACK_VIRTUALENV_USES_PYTHON3',
+    'PYTHON2_DEPREATION'
 ]
 
 PACK_VIRTUALENV_DOESNT_EXIST = '''
@@ -32,3 +33,7 @@
 virtual environment with python2 binary:
 "st2 run packs.setup_virtualenv packs=%(pack)s python3=false"
 '''
+
+PYTHON2_DEPRECATION = 'DEPRECATION WARNING. Support for python 2 will be removed in future StackStorm ' \
+'release(s). Please ensure that all packs used are python 3 compatible. Python 3 will already be used ' \
+'if you upgrade to a newer OS release.'

st2common/st2common/service_setup.py

@@ -42,6 +42,7 @@
 from st2common.util import system_info
 from st2common.services import coordination
 from st2common.logging.misc import add_global_filters_for_all_loggers
+from st2common.constants.error_messages import PYTHON2_DEPRECATION
 
 # Note: This is here for backward compatibility.
 # Function has been moved in a standalone module to avoid expensive in-direct
@@ -186,6 +187,10 @@ def setup(service, config, setup_db=True, register_mq_exchanges=True,
         register_service_in_service_registry(service=service, capabilities=capabilities,
                                              start_heart=True)
 
+    if sys.version_info[0] == 2:
+        LOG.warning(PYTHON2_DEPRECATION)
+
+
 
 def teardown():
     """