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

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

keystonemiddleware 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: Ia6f0e14efd19b0b98227258e7264b4850a197f4f

.zuul.yaml

@@ -2,10 +2,8 @@
     templates:
       - openstack-cover-jobs
       - openstack-lower-constraints-jobs
-      - openstack-python-jobs
       - openstack-python3-ussuri-jobs
       - publish-openstack-docs-pti
       - check-requirements
-      - lib-forward-testing
       - lib-forward-testing-python3
       - release-notes-jobs-python3

doc/requirements.txt

@@ -6,7 +6,6 @@
 doc8>=0.6.0 # Apache-2.0
 openstackdocstheme>=1.20.0 # Apache-2.0
 reno>=2.5.0 # 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
 sphinxcontrib-apidoc>=0.2.0  # BSD
 

releasenotes/notes/drop-py-2-7-6655f421a9cac0a2.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    Python 2.7 support has been dropped. Last release of keystonemiddleware
+    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
@@ -13,25 +14,22 @@ deps =
     -r{toxinidir}/requirements.txt
     -r{toxinidir}/test-requirements.txt
 commands = stestr run {posargs}
+basepython = python3
 
 [testenv:pep8]
-basepython = python3
 commands =
   flake8
   bandit -r keystonemiddleware -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 keystonemiddleware -x tests -n5
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 setenv =
     {[testenv]setenv}
     PYTHON=coverage run --source keystonemiddleware --parallel-mode
@@ -42,7 +40,6 @@ commands =
     coverage xml -o cover/coverage.xml
 
 [testenv:debug]
-basepython = python3
 
 commands = oslo_debug_helper -t keystonemiddleware/tests {posargs}
 
@@ -58,14 +55,12 @@ show-source = True
 exclude = .venv,.tox,dist,doc,*egg,build
 
 [testenv:docs]
-basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands=
     doc8 doc/source
     sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:pdf-docs]
-basepython = python3
 envdir = {toxworkdir}/docs
 deps = {[testenv:docs]deps}
 whitelist_externals =
@@ -77,7 +72,6 @@ commands =
   make -C doc/build/pdf
 
 [testenv:releasenotes]
-basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
@@ -91,7 +85,6 @@ extensions = .rst, .yaml
 max-line-length = 79
 
 [testenv:lower-constraints]
-basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt