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

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

python-keystoneclient 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

Change-Id: Ib6b6f7ca394dfa78cd5c8aeac0941dd625efef3b

.zuul.yaml

@@ -19,11 +19,9 @@
     templates:
       - openstack-cover-jobs
       - openstack-lower-constraints-jobs
-      - openstack-python-jobs
+      - openstack-python3-ussuri-jobs
-      - openstack-python3-train-jobs
       - publish-openstack-docs-pti
       - check-requirements
-      - lib-forward-testing
       - lib-forward-testing-python3
       - release-notes-jobs-python3
     check:

doc/requirements.txt

@@ -4,8 +4,7 @@
 
 # These are needed for docs generation
 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,>=1.6.2 # BSD
-sphinx!=1.6.6,!=1.6.7,>=1.6.2;python_version>='3.4'  # BSD
 reno>=2.5.0 # Apache-2.0
 lxml!=3.7.0,>=3.4.1 # BSD
 fixtures>=3.0.0 # Apache-2.0/BSD

releasenotes/notes/drop-py-2-7-5ac18e82de83fcfa.yaml

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

@@ -1,7 +1,8 @@
 [tox]
-minversion = 2.5.0
+minversion = 3.1.1
 skipsdist = True
-envlist = py27,py37,pep8,releasenotes
+envlist = py37,pep8,releasenotes
+ignore_basepython_conflict = True
 
 [testenv]
 usedevelop = True
@@ -17,25 +18,22 @@ deps =
 commands = find . -type f -name "*.pyc" -delete
            stestr run --slowest {posargs}
 whitelist_externals = find
+basepython = python3
 
 [testenv:pep8]
-basepython = python3
 commands =
   flake8
   bandit -r keystoneclient -x tests -n5
 
 [testenv:bandit]
-basepython = python3
 # NOTE(browne): This is required for the integration test job of the bandit
 # project. Please do not remove.
 commands = bandit -r keystoneclient -x tests -n5
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 setenv =
     PYTHON=coverage run --source keystoneclient --parallel-mode
 commands =
@@ -46,11 +44,9 @@ commands =
     coverage report
 
 [testenv:debug]
-basepython = python3
 commands = oslo_debug_helper -t keystoneclient/tests {posargs}
 
 [testenv:functional]
-basepython = python3
 setenv = {[testenv]setenv}
          OS_TEST_PATH=./keystoneclient/tests/functional
 passenv = OS_*
@@ -67,12 +63,10 @@ show-source = True
 exclude = .venv,.tox,dist,doc,*egg,build
 
 [testenv:docs]
-basepython = python3
 commands = python setup.py build_sphinx
 deps = -r{toxinidir}/doc/requirements.txt
 
 [testenv:pdf-docs]
-basepython = python3
 envdir = {toxworkdir}/docs
 deps = {[testenv:docs]deps}
 whitelist_externals =
@@ -84,7 +78,6 @@ commands =
   make -C doc/build/pdf
 
 [testenv:releasenotes]
-basepython = python3
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 deps = -r{toxinidir}/doc/requirements.txt
 
@@ -93,7 +86,6 @@ import_exceptions =
     keystoneclient.i18n
 
 [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
@@ -102,7 +94,6 @@ deps = bindep
 commands = bindep test
 
 [testenv:lower-constraints]
-basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt