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

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

sahara-dashboard 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: I9bbca7e2d317090dc2d05d08ccf8c45206cd160c

.zuul.yaml

@@ -3,7 +3,6 @@
       - check-requirements
       - horizon-non-primary-django-jobs
       - openstack-lower-constraints-jobs
-      - openstack-python-jobs-horizon
       - openstack-python3-ussuri-jobs-horizon
       - release-notes-jobs-python3
     experimental:
@@ -45,6 +44,8 @@
       devstack_services:
         horizon: true
         tls-proxy: false
+      devstack_localrc:
+        USE_PYTHON3: True
     pre-run: playbooks/sahara-dashboard-integration/pre.yaml
     run: playbooks/sahara-dashboard-integration/run.yaml
     irrelevant-files:

doc/requirements.txt

@@ -2,7 +2,6 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-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
 openstackdocstheme>=1.20.0 # Apache-2.0
 reno>=2.5.0 # Apache-2.0

releasenotes/notes/drop-py-2-7-0812be5ce1752d7c.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    Python 2.7 support has been dropped. Last release of sahara-dashboard
+    to support python 2.7 is OpenStack Train. The minimum version of Python now
+    supported by sahara-dashboard is Python 3.6.

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
     Programming Language :: Python :: 3.7

tox.ini

@@ -1,9 +1,10 @@
 [tox]
 minversion = 2.0
-envlist = py3-{dj111,dj22},py27,py37,pep8
+envlist = py3-{dj111,dj22},py37,pep8
 skipsdist = True
 
 [testenv]
+basepython = python3
 usedevelop = True
 install_command = pip install {opts} {packages}
 deps = -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
@@ -15,28 +16,23 @@ commands =
   dj22: pip install django>=2.2,<2.3
   {envpython} {toxinidir}/manage.py test --settings=sahara_dashboard.test.settings --exclude-tag integration {posargs}
 
-[testenv:py27]
-setenv =
-   DJANGO_SETTINGS_MODULE=sahara_dashboard.test.settings
-
 [testenv:py36]
+basepython = python3.6
 setenv =
    DJANGO_SETTINGS_MODULE=sahara_dashboard.test.settings
 
 [testenv:py37]
+basepython = python3.7
 setenv =
    DJANGO_SETTINGS_MODULE=sahara_dashboard.test.settings
 
 [testenv:pep8]
-basepython = python3
 commands = flake8
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
-[testenv:py27integration]
-basepython = python2.7
+[testenv:integration]
 passenv = AVCONV_INSTALLED
 setenv =
   INTEGRATION_TESTS=1
@@ -45,13 +41,11 @@ setenv =
 commands = {envpython} {toxinidir}/manage.py test --settings=sahara_dashboard.test.settings --verbosity 2 --tag integration {posargs}
 
 [testenv:releasenotes]
-basepython = python3
 deps = -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
        -r{toxinidir}/doc/requirements.txt
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:cover]
-basepython = python3
 commands =
   coverage erase
   coverage run {toxinidir}/manage.py test --settings=sahara_dashboard.test.settings --exclude-tag integration {posargs}
@@ -59,7 +53,6 @@ commands =
   coverage xml -o cover/coverage.xml
 
 [testenv:debug]
-basepython = python3
 commands = oslo_debug_helper -t sahara_dashboard/test {posargs}
 
 [flake8]
@@ -72,7 +65,6 @@ builtins = _
 exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build,.ropeproject,tools,.tmp
 
 [testenv:bindep]
-basepython = python3
 # Do not install any requirements. We want this to be fast and work even if
 # system dependencies are missing, since it's used to tell you what system
 # dependencies are missing! This also means that bindep must be installed
@@ -81,7 +73,6 @@ deps = bindep
 commands = bindep test
 
 [testenv:lower-constraints]
-basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt