Drop python 2.7 support and testing

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

python-zunclient 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: I5f5eead1282cea042152d3f78b19667ffe6c6929

.zuul.yaml

@@ -17,7 +17,6 @@
     templates:
       - openstack-cover-jobs
       - openstack-lower-constraints-jobs
-      - openstack-python-jobs
       - openstack-python3-ussuri-jobs
       - check-requirements
       - publish-openstack-docs-pti

doc/requirements.txt

@@ -2,6 +2,5 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 openstackdocstheme>=1.20.0 # Apache-2.0
-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
 reno>=2.5.0 # Apache-2.0

playbooks/zunclient-devstack-docker-sql/run.yaml

@@ -30,6 +30,7 @@
           cat << 'EOF' >>"/tmp/dg-local.conf"
           [[local|localrc]]
           enable_plugin zun https://opendev.org/openstack/zun
+          USE_PYTHON3=True
 
           EOF
         executable: /bin/bash

releasenotes/notes/drop-py-2-7-c18f48ee28088c4a.yaml

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

setup.cfg

@@ -13,8 +13,6 @@ 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 :: 3.6
     Programming Language :: Python :: 3.7

tox.ini

@@ -1,9 +1,11 @@
 [tox]
-minversion = 2.0
+minversion = 3.1.1
-envlist = py27,py37,pep8
+envlist = py37,pep8
 skipsdist = True
+ignore_basepython_conflict = True
 
 [testenv]
+basepython = python3
 usedevelop = True
 install_command = pip install -U {opts} {packages}
 whitelist_externals = bash
@@ -22,22 +24,15 @@ commands =
 
 
 [testenv:bandit]
-basepython = python3
 deps = -r{toxinidir}/test-requirements.txt
 commands = bandit -r zunclient -x tests -n5 -ll
 
 [testenv:pypy]
-basepython = python3
 deps = setuptools<3.2
        -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 
 [testenv:debug]
-basepython = python3
-commands = oslo_debug_helper -t zunclient/tests {posargs}
-
-[testenv:debug-py27]
-basepython = python2.7
 commands = oslo_debug_helper -t zunclient/tests {posargs}
 
 [testenv:debug-py34]
@@ -45,7 +40,6 @@ basepython = python3.4
 commands = oslo_debug_helper -t zunclient/tests {posargs}
 
 [testenv:docs]
-basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/requirements.txt
@@ -54,14 +48,12 @@ commands =
   sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:pep8]
-basepython = python3
 commands =
   flake8
   # Run security linter
   bandit -r zunclient -x tests -n5 -ll
 
 [testenv:releasenotes]
-basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/requirements.txt
@@ -70,11 +62,9 @@ commands =
   sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 setenv =
     {[testenv]setenv}
     PYTHON=coverage run --source zunclient --parallel-mode
@@ -109,7 +99,6 @@ setenv =
 passenv = OS_*
 
 [testenv:lower-constraints]
-basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt