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

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

Karbor 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: Id923a1e18a1ba2439eda11a88abab64a3b32cab1

.zuul.yaml

@@ -3,7 +3,6 @@
       - openstack-cover-jobs
       - openstack-lower-constraints-jobs
       - check-requirements
-      - openstack-python-jobs
       - openstack-python3-ussuri-jobs
       - publish-openstack-docs-pti
     check:

playbooks/legacy/karbor-dsvm-fullstack/run.yaml

@@ -56,7 +56,7 @@
           export DEVSTACK_GATE_TEMPEST=0
           export DEVSTACK_GATE_NEUTRON=1
           export DEVSTACK_GATE_INSTALL_TESTONLY=1
-
+          export DEVSTACK_GATE_USE_PYTHON3=True
 
           export BRANCH_OVERRIDE=default
           if [ "$BRANCH_OVERRIDE" != "default" ] ; then

releasenotes/notes/drop-py-2-7-84b4daca6e383f97.yaml

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

test-requirements.txt

@@ -7,8 +7,7 @@ botocore>=1.5.1 # Apache-2.0
 coverage!=4.4,>=4.0 # Apache-2.0
 croniter>=0.3.4 # MIT License
 python-subunit>=1.0.0 # Apache-2.0/BSD
-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
+sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.2 # BSD
 oslotest>=3.2.0 # Apache-2.0
 stestr>=2.0.0 # Apache-2.0
 taskflow>=2.16.0 # Apache-2.0

tox.ini

@@ -1,9 +1,11 @@
 [tox]
-minversion = 2.0
-envlist = py27,py37,pypy,pep8
+minversion = 3.1.1
+envlist = py37,pypy,pep8
 skipsdist = True
+ignore_basepython_conflict = True
 
 [testenv]
+basepython = python3
 usedevelop = True
 install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master} -U {opts} {packages}
 setenv =
@@ -20,7 +22,6 @@ commands =
   stestr slowest
 
 [testenv:fullstack]
-basepython = python2.7
 setenv = OS_TEST_PATH=./karbor/tests/fullstack
          OS_TEST_TIMEOUT=3600
 commands =
@@ -29,15 +30,12 @@ commands =
   stestr slowest
 
 [testenv:pep8]
-basepython = python3
 commands = flake8
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 setenv =
     {[testenv]setenv}
     PYTHON=coverage run --source karbor --parallel-mode
@@ -49,18 +47,15 @@ commands =
   coverage report
 
 [testenv:docs]
-basepython = python3
 whitelist_externals = sh /bin/rm
 commands = /bin/rm -rf doc/build
            /bin/rm -rf doc/source/contributor/api
            python setup.py build_sphinx
 
 [testenv:debug]
-basepython = python3
 commands = oslo_debug_helper -t karbor/tests/unit {posargs}
 
 [testenv:api-ref]
-basepython = python3
 # This environment is called from CI scripts to test and publish
 # the API Ref to docs.openstack.org.
 whitelist_externals = sh /bin/rm
@@ -70,15 +65,12 @@ commands =
   sphinx-build -W -b html -d api-ref/build/doctrees api-ref/source api-ref/build/html/
 
 [testenv:releasenotes]
-basepython = python3
 commands = sphinx-build -a -E -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:genconfig]
-basepython = python3
 commands = oslo-config-generator --config-file etc/oslo-config-generator/karbor.conf
 
 [testenv:genpolicy]
-basepython = python3
 commands = oslopolicy-sample-generator --config-file=etc/karbor-policy-generator.conf
 
 [flake8]
@@ -91,7 +83,6 @@ exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build,releasenotes
 import_exceptions = karbor.i18n
 
 [testenv:lower-constraints]
-basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt