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

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

monasca-agent 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: I6cd8c92e4c7c9228ae14596e1535f40184a5ae22

.zuul.yaml

@@ -1,12 +1,9 @@
 - project:
     templates:
-      - openstack-python-jobs
       - openstack-python3-ussuri-jobs
     check:
       jobs:
         - build-monasca-docker-image
-        - monasca-tempest-python2-influxdb:
-            voting: false
         - monasca-tempest-python3-influxdb:
             voting: false
     post:

releasenotes/notes/drop-py-2-7-9a5a1c167be90f99.yaml

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

requirements.txt

@@ -21,7 +21,6 @@ redis>=2.10.0 # MIT
 six>=1.10.0 # MIT
 stevedore>=1.20.0 # Apache-2.0
 tornado>=4.5.3 # Apache-2.0
-futures>=3.0.0;python_version=='2.7' or python_version=='2.6' # BSD
 # NOTE(sdague): before allowing in >= 0.21 please be sure
 # https://github.com/eventlet/eventlet/issues/401 is resolved
 eventlet!=0.18.3,!=0.20.1,>=0.18.2 # MIT

setup.cfg

@@ -16,8 +16,6 @@ classifier=
     License :: OSI Approved :: Apache Software License
     Topic :: System :: Monitoring
     Operating System :: POSIX :: Linux
-    Programming Language :: Python :: 2
-    Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7

tox.ini

@@ -1,9 +1,10 @@
 [tox]
-envlist = py27,py37,pep8,cover
+envlist = py37,pep8,cover
 minversion = 2.5
 skipsdist = True
 
 [testenv]
+basepython = python3
 usedevelop = True
 setenv =
     VIRTUAL_ENV={envdir}
@@ -22,12 +23,6 @@ commands =
   find . -type f -name "*.pyc" -delete
   rm -Rf .testrepository/times.dbm
 
-[testenv:py27]
-basepython = python2.7
-commands =
-  {[testenv]commands}
-  stestr run {posargs}
-
 [testenv:py36]
 basepython = python3.6
 commands =
@@ -35,7 +30,6 @@ commands =
   stestr run {posargs}
 
 [testenv:cover]
-basepython = python3
 commands =
   {[testenv]commands}
   coverage erase
@@ -43,7 +37,6 @@ commands =
   coverage report
 
 [testenv:bandit]
-basepython = python3
 commands =
   # B101 - asserts used on purpose
   # Following rules should be fixed in future
@@ -67,20 +60,17 @@ commands =
   bandit -r monasca_agent -n5 -s B101,B602,B603,B301,B303,B311,B403,B404,B405,B310,B320,B410,B411,B501,B504,B605,B607,B608 -x {toxinidir}/tests
 
 [testenv:flake8]
-basepython = python3
 commands =
   flake8 monasca_agent
   flake8 monasca_setup
   flake8 tests
 
 [testenv:pep8]
-basepython = python3
 commands =
   {[testenv:flake8]commands}
   {[testenv:bandit]commands}
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:bindep]
@@ -88,7 +78,6 @@ commands = {posargs}
 # system dependencies are missing, since it's used to tell you what system
 # dependencies are missing! This also means that bindep must be installed
 # separately, outside of the requirements files.
-basepython = python3
 deps = bindep
 commands = bindep test