Cleanup py27 support

This repo is now testing only with Python 3, so let's 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
- Update classifiers
- Update requirements, no need for python_version anymore
- Use newer openstackdocstheme version

Change-Id: Ic7696a6ba0fc213b59edf87cf9ef2a804ebca94f

lower-constraints.txt

@@ -19,7 +19,6 @@ eventlet==0.20.0
 extras==1.0.0
 fasteners==0.7.0
 fixtures==3.0.0
-futures==3.0.0;python_version=='2.7' or python_version=='2.6'
 gitdb==0.6.4
 GitPython==1.0.1
 idna==2.6
@@ -43,7 +42,7 @@ msgpack-python==0.4.0
 munch==2.1.0
 netaddr==0.7.18
 netifaces==0.10.4
-openstackdocstheme==1.20.0
+openstackdocstheme==1.31.2
 openstacksdk==0.11.2
 os-client-config==1.28.0
 os-service-types==1.2.0

requirements.txt

@@ -4,8 +4,7 @@
 
 pbr!=2.1.0,>=2.0.0 # Apache-2.0
 Babel!=2.4.0,>=2.3.4 # BSD
-GitPython>=1.0.1;python_version>='3.0' # BSD License (3 clause)
-GitPython>=1.0.1,<2.1.12;python_version<'3.0' # BSD License (3 clause)
+GitPython>=1.0.1 # BSD License (3 clause)
 eventlet!=0.20.1,>=0.20.0 # MIT
 python-heatclient>=1.10.0 # Apache-2.0
 oslo.config>=5.2.0 # Apache-2.0
@@ -13,8 +12,7 @@ oslo.log>=3.36.0 # Apache-2.0
 oslo.rootwrap>=5.8.0 # Apache-2.0
 oslo.utils>=3.33.0 # Apache-2.0
 python-glanceclient>=2.8.0 # Apache-2.0
-python-ironicclient!=2.5.2,!=2.7.1,!=3.0.0,>=2.3.0,<4.0.0;python_version=='2.7' # Apache-2.0
-python-ironicclient!=2.5.2,!=2.7.1,!=3.0.0,>=2.3.0;python_version>='3.6' # Apache-2.0
+python-ironicclient!=2.5.2,!=2.7.1,!=3.0.0,>=2.3.0 # Apache-2.0
 six>=1.10.0 # MIT
 mistral-lib>=0.3.0 # Apache-2.0
 oslo.concurrency>=3.26.0 # Apache-2.0
@@ -30,7 +28,6 @@ python-zaqarclient>=1.0.0 # Apache-2.0
 python-keystoneclient>=3.8.0 # Apache-2.0
 keystoneauth1>=3.4.0 # Apache-2.0
 tenacity>=4.4.0 # Apache-2.0
-futures>=3.0.0;python_version=='2.7' or python_version=='2.6'  # BSD
 metalsmith>=0.13.0 # Apache-2.0
 jsonschema>=2.6.0 # MIT
 requests>=2.18.0,!=2.20.0  # Apache-2.0

setup.cfg

@@ -6,6 +6,7 @@ description-file =
 author = OpenStack
 author-email = openstack-discuss@lists.openstack.org
 home-page = https://docs.openstack.org/tripleo-common/latest/
+python-requires = >=3.6
 classifier =
     Environment :: OpenStack
     Intended Audience :: Information Technology
@@ -13,8 +14,8 @@ 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 :: Implementation :: CPython
+    Programming Language :: Python :: 3 :: Only
     Programming Language :: Python :: 3
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
@@ -45,14 +46,6 @@ data_files =
     share/ansible/roles/ = roles/*
     share/ansible/plugins/ = ansible_plugins/*
 
-[build_sphinx]
-source-dir = doc/source
-build-dir = doc/build
-all_files = 1
-
-[upload_sphinx]
-upload-dir = doc/build/html
-
 [compile_catalog]
 directory = tripleo_common/locale
 domain = tripleo-common

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>=2.0.0'],
     pbr=True)

test-requirements.txt

@@ -2,13 +2,12 @@
 # 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
+openstackdocstheme>=1.31.2 # Apache-2.0
 
 coverage!=4.4,>=4.0 # Apache-2.0
 docutils>=0.11 # OSI-Approved Open Source, Public Domain
 python-subunit>=1.0.0 # Apache-2.0/BSD
-sphinx>=1.8.0,<2.0.0;python_version=='2.7' # BSD
-sphinx>=1.8.0,!=2.1.0;python_version>='3.4' # BSD
+sphinx>=1.8.0,!=2.1.0 # BSD
 oslotest>=3.2.0 # Apache-2.0
 stestr>=2.0.0 # Apache-2.0
 testscenarios>=0.4 # Apache-2.0/BSD