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

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

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: I3cf8525b430031303dd0ecfbb6719ec935f6dd91

.zuul.yaml

@@ -11,7 +11,6 @@
 
 - project:
     templates:
-      - openstack-python-jobs
       - openstack-python3-ussuri-jobs
       - check-requirements
       - publish-openstack-docs-pti

setup.cfg

@@ -6,6 +6,7 @@ description-file =
 author = OpenStack
 author-email = openstack-discuss@lists.openstack.org
 home-page = https://docs.openstack.org/os-api-ref/latest/
+python-requires = >=3.6
 classifier =
     Environment :: OpenStack
     Intended Audience :: Information Technology
@@ -13,25 +14,17 @@ 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
+    Programming Language :: Python :: 3 :: Only
+    Programming Language :: Python :: Implementation :: CPython
+
 
 [files]
 packages =
     os_api_ref
 
-[build_sphinx]
-source-dir = doc/source
-build-dir = doc/build
-all_files = 1
-warning-is-error = 1
-
-[upload_sphinx]
-upload-dir = doc/build/html
-
 [compile_catalog]
 directory = os_api_ref/locale
 domain = os_api_ref

tox.ini

@@ -1,12 +1,13 @@
 [tox]
-minversion = 2.0
-envlist = py27,py37,pep8,docs
+minversion = 3.1.1
+envlist = py37,pep8,docs
+ignore_basepython_conflict = True
 skipsdist = True
 
 [testenv]
+basepython = python3
 setenv =
     VIRTUAL_ENV={envdir}
-install_command = pip install -U {opts} {packages}
 deps =
      -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
      -r{toxinidir}/requirements.txt
@@ -14,18 +15,15 @@ deps =
 commands = stestr run {posargs}
 
 [testenv:pep8]
-basepython = python3
 commands = flake8 {posargs}
 
 [testenv:venv]
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 commands = python setup.py test --coverage --testr-args='{posargs}'
 
 [testenv:docs]
-basepython = python3
 deps =
     -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
     -r{toxinidir}/requirements.txt
@@ -33,7 +31,6 @@ deps =
 commands = sphinx-build -W -b html -d doc/build/doctrees doc/source doc/build/html
 
 [testenv:debug]
-basepython = python3
 commands = oslo_debug_helper {posargs}
 
 [flake8]