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

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

magnum-ui 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

Depends-On: https://review.opendev.org/#/c/693631/
Change-Id: I9630d3da80bd79f3886bc82e891e827238925704

.zuul.yaml

@@ -4,7 +4,7 @@
       - horizon-non-primary-django-jobs
       - horizon-nodejs10-jobs
       - openstack-lower-constraints-jobs-horizon
-      - openstack-python-jobs-horizon
+      - openstack-python3-ussuri-jobs-horizon
       - publish-openstack-docs-pti
       - release-notes-jobs-python3
     check:

doc/requirements.txt

@@ -8,7 +8,6 @@
 #
 openstackdocstheme>=1.18.1 # 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
 

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
 

tox.ini

@@ -1,9 +1,10 @@
 [tox]
-envlist = pep8,py27-local,py3-{dj111,dj22},eslint,karma-local,docs-local,releasenotes,lower-constraints-local
+envlist = pep8,,py3-{dj111,dj22},eslint,karma-local,docs-local,releasenotes,lower-constraints-local
 minversion = 2.3.2
 skipsdist = True
 
 [testenv]
+basepython = python3
 usedevelop = True
 setenv = VIRTUAL_ENV={envdir}
          NOSE_WITH_OPENSTACK=1
@@ -27,11 +28,9 @@ commands =
   pip install -e ../horizon
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:pep8]
-basepython = python3
 commands = flake8 {posargs}
 
 [flake8]
@@ -42,7 +41,6 @@ exclude = .git,.tox,dist,*lib/python*,*egg,build,panel_template,dash_template,lo
 max-complexity = 20
 
 [testenv:cover]
-basepython = python3
 commands =
   coverage erase
   coverage run {toxinidir}/manage.py test magnum_ui --settings=magnum_ui.test.settings {posargs} --exclude-dir=magnum_ui/test/integration_tests {posargs}
@@ -52,12 +50,6 @@ commands =
 # NOTE(shu-mutow): On CI infra, horizon will be installed
 # according to job setting. but on local, we need to install
 # horizon from master branch.
-[testenv:py27-local]
-basepython = python2.7
-commands =
-  {[testenv:hz-local]commands}
-  {[testenv]commands}
-
 [testenv:py36-local]
 basepython = python3.6
 commands =
@@ -65,7 +57,6 @@ commands =
   {[testenv]commands}
 
 [testenv:eslint]
-basepython = python3
 whitelist_externals =
   npm
 commands =
@@ -76,7 +67,6 @@ commands =
 # from master branch into karma environment with python3.x for testing javascripts.
 # Horizon from master is needed to be cloned into ../horizon on both local and CI.
 [testenv:karma]
-basepython = python3
 whitelist_externals =
   {[testenv:eslint]whitelist_externals}
 commands =
@@ -84,14 +74,12 @@ commands =
   npm run test
 
 [testenv:karma-local]
-basepython = python3
 whitelist_externals =
   {[testenv:eslint]whitelist_externals}
 commands =
   {[testenv:karma]commands}
 
 [testenv:docs]
-basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/doc/requirements.txt
@@ -99,7 +87,6 @@ commands=
   sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:pdf-docs]
-basepython = python3
 deps = {[testenv:docs]deps}
 whitelist_externals =
   make
@@ -110,7 +97,6 @@ commands =
   make -C doc/build/pdf
 
 [testenv:docs-local]
-basepython = python3
 deps =
   {[testenv:docs]deps}
 commands=
@@ -118,21 +104,18 @@ commands=
   {[testenv:docs]commands}
 
 [testenv:releasenotes]
-basepython = python3
 deps =
   {[testenv:docs]deps}
 commands =
   sphinx-build -a -E -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:lower-constraints]
-basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt
   -r{toxinidir}/requirements.txt
 
 [testenv:lower-constraints-local]
-basepython = python3
 deps =
   {[testenv:lower-constraints]deps}
 commands =