Drop python 2.7 support and testing

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

trove-tempest-plugin 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://review.opendev.org/#/c/691178/

Change-Id: Id689113d1cca11f27cee7598b841e365225b50df

.zuul.yaml

@@ -19,6 +19,39 @@
     name: trove-tempest-plugin
     parent: devstack-tempest
     timeout: 7800
+    description: |
+      This job is for stable branch prior to Ussuri for testing
+      on py2.
+    required-projects:
+      - openstack/neutron
+      - openstack/trove
+      - openstack/trove-tempest-plugin
+      - openstack/tempest
+    vars:
+      tox_envlist: all
+      devstack_localrc:
+        TEMPEST_PLUGINS: /opt/stack/trove-tempest-plugin
+        USE_PYTHON3: False
+      devstack_plugins:
+        trove: https://opendev.org/openstack/trove
+      devstack_services:
+        tempest: true
+        tls-proxy: false
+      tempest_test_regex: ^trove_tempest_plugin\.tests
+    branches:
+      - stable/ocata
+      - stable/pike
+      - stable/queens
+      - stable/rocky
+      - stable/stein
+      - stable/train
+
+- job:
+    name: trove-tempest-plugin
+    parent: devstack-tempest
+    timeout: 7800
+    description: |
+      This job is for testing on py3 which is Ussuri onwards.
     required-projects: &base_required_projects
       - openstack/python-troveclient
       - openstack/trove

releasenotes/notes/drop-py-2-7-c3f42fa06d0485d9.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    Python 2.7 support has been dropped. Last release of trove-tempest-plugin
+    to support py2.7 is OpenStack Train. The minimum version of Python now
+    supported by trove-tempest-plugin is Python 3.6.

setup.cfg

@@ -13,11 +13,9 @@ classifier =
     License :: OSI Approved :: Apache Software License
     Operating System :: POSIX :: Linux
     Programming Language :: Python
-    Programming Language :: Python :: 2
-    Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.3
-    Programming Language :: Python :: 3.4
+    Programming Language :: Python :: 3.6
+    Programming Language :: Python :: 3.7
 
 [files]
 packages =

tox.ini

@@ -1,9 +1,11 @@
 [tox]
-minversion = 2.0
-envlist = py36,py35,py27,pypy,pep8
+minversion = 3.1.1
+envlist = py36,py35,pypy,pep8
 skipsdist = True
+ignore_basepython_conflict = True
 
 [testenv]
+basepython = python3
 usedevelop = True
 install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
 setenv =
@@ -16,15 +18,12 @@ deps = -r{toxinidir}/test-requirements.txt
 commands = stestr run {posargs}
 
 [testenv:pep8]
-basepython = python3
 commands = flake8 {posargs}
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 setenv =
     VIRTUAL_ENV={envdir}
     PYTHON=coverage run --source trove_tempest_plugin --parallel-mode
@@ -35,7 +34,6 @@ commands =
     coverage xml -o cover/coverage.xml
 
 [testenv:docs]
-basepython = python3
 deps =
     -r{toxinidir}/doc/requirements.txt
 commands =
@@ -43,7 +41,6 @@ commands =
     sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:releasenotes]
-basepython = python3
 deps =
     -r{toxinidir}/doc/requirements.txt
 commands =