[ussuri][goal] Drop python 2.7 support and testing

OpenStack is dropping the py2.7 support in ussuri cycle.

monasca-notification is ready with python 3 and ok to drop the
python 2.7 support.

Complete discussion & schedule can be found in
- http://lists.openstack.org/pipermail/openstack-discuss/2019-October/010142.html
- https://etherpad.openstack.org/p/drop-python2-support

Ussuri Communtiy-wide goal:
https://governance.openstack.org/tc/goals/selected/ussuri/drop-py27.html

Depends-On: https://review.opendev.org/#/c/693631/
Change-Id: Ic69f559bc0bcd791fa33a978cd27cf1de10dba2d

.zuul.yaml

@@ -3,14 +3,11 @@
       - check-requirements
       - openstack-cover-jobs
       - openstack-lower-constraints-jobs
-      - openstack-python-jobs
       - openstack-python3-ussuri-jobs
       - release-notes-jobs-python3
     check:
       jobs:
         - build-monasca-docker-image
-        - monasca-tempest-python2-influxdb:
-            voting: false
         - monasca-tempest-python3-influxdb:
             voting: false
     post:

doc/requirements.txt

@@ -1,7 +1,6 @@
 # The order of packages is significant, because pip processes them in the order
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
-sphinx!=1.6.6,!=1.6.7,>=1.6.2,<2.0.0;python_version=='2.7'  # BSD
 sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.2;python_version>='3.4'  # BSD
 openstackdocstheme>=1.20.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0

releasenotes/notes/drop-py-2-7-285e126a13e4b5a7.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    Python 2.7 support has been dropped. Last release of monasca-notification
+    to support python 2.7 is OpenStack Train. The minimum version of Python now
+    supported by monasca-notification is Python 3.6.

setup.cfg

@@ -9,8 +9,6 @@ classifier=
     Topic :: System :: Monitoring
     Operating System :: POSIX :: Linux
     Programming Language :: Python
-    Programming Language :: Python :: 2
-    Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7

test-requirements.txt

@@ -8,7 +8,6 @@ Babel!=2.4.0,>=2.3.4 # BSD
 hacking>=1.1.0,<1.2.0 # Apache-2.0
 coverage!=4.4,>=4.0 # Apache-2.0
 mock>=2.0.0 # BSD
-funcsigs>=1.0.0;python_version=='2.7' or python_version=='2.6' # Apache-2.0
 stestr>=1.0.0 # Apache-2.0
 oslotest>=3.2.0 # Apache-2.0
 testrepository>=0.0.18 # Apache-2.0/BSD

tox.ini

@@ -1,9 +1,10 @@
 [tox]
-envlist = py27,py37,pep8,cover
+envlist = py37,pep8,cover
 minversion = 2.7
 skipsdist = True
 
 [testenv]
+basepython = python3
 setenv =
     VIRTUAL_ENV={envdir}
     OS_TEST_PATH=tests
@@ -25,7 +26,6 @@ commands =
  stestr run {posargs}
 
 [testenv:cover]
-basepython = python3
 commands =
   coverage erase
   python setup.py test --coverage --testr-args='{posargs}' \
@@ -33,33 +33,27 @@ commands =
   coverage report
 
 [testenv:debug]
-basepython = python3
 commands =
   oslo_debug_helper -t ./monasca_notification/tests {posargs}
 
 [testenv:pep8]
-basepython = python3
 commands =
   {[testenv:flake8]commands}
   {[testenv:bandit]commands}
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:flake8]
-basepython = python3
 commands =
   flake8 monasca_notification
   flake8 tests
 
 [testenv:bandit]
-basepython = python3
 commands =
   bandit -r monasca_notification -n5 -x monasca_notification/tests
 
 [testenv:genconfig]
-basepython = python3
 description = Generates an example of monasca-notification configuration file
 commands = oslo-config-generator \
   --config-file={toxinidir}/config-generator/notification.conf
@@ -78,7 +72,6 @@ import_exceptions =
   six.moves
 
 [testenv:lower-constraints]
-basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt
@@ -92,7 +85,6 @@ commands =
     releasenotes/source releasenotes/build/html
 
 [testenv:bindep]
-basepython = python3
 # Do not install any requirements. We want this to be fast and work even if
 # system dependencies are missing, since it's used to tell you what system
 # dependencies are missing! This also means that bindep must be installed