Drop python 2.7 support and testing

Ussuri Communtiy-wide goal:
https://governance.openstack.org/tc/goals/selected/ussuri/drop-py27.html

Change-Id: If6d6357501dfdff5a5edb53f24104e216607ea00
Sem-Ver: api-break

.zuul.yaml

@@ -41,7 +41,6 @@
       - ^doc/.*$
       - ^releasenotes/.*$
 
-
 - project:
     check:
       jobs:
@@ -52,10 +51,8 @@
         - oslo.log-jsonformatter
     templates:
       - check-requirements
-      - lib-forward-testing
       - lib-forward-testing-python3
       - openstack-lower-constraints-jobs
-      - openstack-python-jobs
       - openstack-python3-ussuri-jobs
       - periodic-stable-jobs
       - publish-openstack-docs-pti

doc/requirements.txt

@@ -2,8 +2,7 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-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
 openstackdocstheme>=1.20.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
 

releasenotes/notes/drop-python27-support-0fe4909a5468feb3.yaml

@@ -0,0 +1,5 @@
+---
+upgrade:
+  - |
+    Python 2.7 is no longer supported. The minimum supported version of Python
+    is now Python 3.6.

setup.cfg

@@ -6,6 +6,7 @@ description-file =
 author = OpenStack
 author-email = openstack-discuss@lists.openstack.org
 home-page = https://docs.openstack.org/oslo.log/latest
+python-requires = >=3.6
 classifier =
     Environment :: OpenStack
     Intended Audience :: Information Technology
@@ -13,11 +14,11 @@ 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 =
@@ -35,9 +36,6 @@ oslo.config.opts =
 console_scripts =
     convert-json = oslo_log.cmds.convert_json:main
 
-[upload_sphinx]
-upload-dir = doc/build/html
-
 [compile_catalog]
 directory = oslo_log/locale
 domain = oslo_log

tox.ini

@@ -1,7 +1,7 @@
 [tox]
 minversion = 3.1
-envlist = py27,py36,py37,pep8
-ignore_basepython_conflict = True
+envlist = py36,py37,pep8
+ignore_basepython_conflict = true
 
 [testenv]
 basepython = python3