Cleanup py27 support

Make a few cleanups:
- Remove python 2.7 stanza from setup.py
- Add requires on python >= 3.6 to setup.cfg so that pypi and pip
  know about the requirement
- Remove obsolete sections from setup.cfg:
  * Wheel is not needed for python 3 only repo
  * Some other sections are obsolete
- Update classifiers
- Update requirements, no need for python_version anymore

Change-Id: I1db16203ad150c6286c0ca833c01a456981d0a73

setup.cfg

@@ -5,7 +5,8 @@ description-file =
     README.rst
 author = OpenStack
 author-email = openstack-discuss@lists.openstack.org
-home-page = http://docs.openstack.org/developer/ceilometermiddleware
+home-page = https://docs.openstack.org/ceilometermiddleware/latest/
+python-requires = >=3.6
 classifier =
     Environment :: OpenStack
     Intended Audience :: Information Technology
@@ -13,6 +14,8 @@ classifier =
     License :: OSI Approved :: Apache Software License
     Operating System :: POSIX :: Linux
     Programming Language :: Python
+    Programming Language :: Python :: Implementation :: CPython
+    Programming Language :: Python :: 3 :: Only
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
@@ -25,14 +28,6 @@ packages =
 paste.filter_factory =
     swift = ceilometermiddleware.swift:filter_factory
 
-[build_sphinx]
-source-dir = doc/source
-build-dir = doc/build
-all_files = 1
-
-[upload_sphinx]
-upload-dir = doc/build/html
-
 [compile_catalog]
 directory = ceilometermiddleware/locale
 domain = ceilometermiddleware

setup.py

@@ -13,17 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# THIS FILE IS MANAGED BY THE GLOBAL REQUIREMENTS REPO - DO NOT EDIT
 import setuptools
 
-# In python < 2.7.4, a lazy loading of package `pbr` will break
-# setuptools if some other modules registered functions in `atexit`.
-# solution from: http://bugs.python.org/issue15881#msg170215
-try:
-    import multiprocessing  # noqa
-except ImportError:
-    pass
-
 setuptools.setup(
     setup_requires=['pbr>=1.8'],
     pbr=True)

test-requirements.txt

@@ -4,8 +4,7 @@
 
 coverage>=3.6 # Apache-2.0
 python-subunit>=0.0.18 # Apache-2.0/BSD
-sphinx!=1.6.6,!=1.6.7,<2.0.0;python_version=='2.7'  # BSD
-sphinx!=1.6.6,!=1.6.7,!=2.1.0;python_version>='3.4'  # BSD
+sphinx!=1.6.6,!=1.6.7,!=2.1.0 # BSD
 openstackdocstheme>=1.17.0  # Apache-2.0
 oslotest>=1.10.0 # Apache-2.0
 stestr>=2.0.0 # Apache-2.0

tox.ini

@@ -2,28 +2,27 @@
 minversion = 1.8
 envlist = py37,pypy,pep8,releasenotes
 skipsdist = True
+ignore_basepython_conflict = True
 
 [testenv]
+basepython = python3
 usedevelop = True
-# NOTE(tonyb): This project has chosen to *NOT* consume upper-constraints.txt
-install_command = pip install -U {opts} {packages}
+install_command = pip install {opts} {packages}
 setenv =
    VIRTUAL_ENV={envdir}
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
+       -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
 commands = stestr run --slowest {posargs}
 
 [testenv:pep8]
-basepython = python3
 deps = hacking>=0.12,<0.13
 commands = flake8
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 setenv =
     PYTHON=coverage run --source $project --parallel-mode
 commands =
@@ -33,15 +32,12 @@ commands =
     coverage xml -o cover/coverage.xml
 
 [testenv:docs]
-basepython = python3
 commands = sphinx-build -W -b html -d doc/build/doctrees doc/source doc/build/html
 
 [testenv:debug]
-basepython = python3
 commands = oslo_debug_helper {posargs}
 
 [testenv:releasenotes]
-basepython = python3
 commands = sphinx-build -a -E -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [flake8]