Drop python 2 support and testing

This is part of Ussuri goal tracked for Neutron stadium at:
https://etherpad.openstack.org/p/neutron-train-zuulv3-py27drop

Change-Id: I325e26fb190890d29fba015c5105b9488d71367c

.zuul.yaml

@@ -19,7 +19,6 @@
       - check-requirements
       - openstack-cover-jobs-neutron
       - openstack-lower-constraints-jobs-neutron
-      - openstack-python-jobs-neutron
       - openstack-python3-ussuri-jobs-neutron
       - publish-openstack-docs-pti
       - release-notes-jobs-python3

releasenotes/notes/drop-py27-support-795303ca12cccd34.yaml

@@ -0,0 +1,7 @@
+---
+upgrade:
+  - |
+    Python 2.7 support has been dropped. Last release of
+    neutron-dynamic-routing to support python 2.7 is OpenStack Train. The
+    minimum version of Python now supported by neutron-dynamic-routing is
+    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/neutron-dynamic-routing/latest/
+python-requires = >=3.6
 classifier =
     Environment :: OpenStack
     Intended Audience :: Information Technology
@@ -13,8 +14,6 @@ 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

@@ -8,7 +8,6 @@ fixtures>=3.0.0 # Apache-2.0/BSD
 flake8-import-order==0.12 # LGPLv3
 mock>=2.0.0 # BSD
 python-subunit>=1.0.0 # Apache-2.0/BSD
-sphinx!=1.6.6,!=1.6.7,>=1.6.5,<2.0.0;python_version=='2.7'  # BSD
 sphinx!=1.6.6,!=1.6.7,!=2.1.0,>=1.6.5;python_version>='3.4' # BSD
 sphinxcontrib-svg2pdfconverter>=0.1.0 # BSD
 openstackdocstheme>=1.18.1 # Apache-2.0

tox.ini

@@ -1,6 +1,6 @@
 [tox]
-envlist = py27,py37,pep8,pylint
-minversion = 2.5.0
+envlist = py37,pep8,pylint
+minversion = 3.1.1
 skipsdist = True
 
 [testenv]
@@ -26,14 +26,12 @@ commands =
 # mode. To do this define the TRACE_FAILONLY environmental variable.
 
 [testenv:functional]
-basepython = python3
 setenv = OS_TEST_PATH=./neutron_dynamic_routing/tests/functional
 commands =
   stestr run {posargs}
   stestr slowest
 
 [testenv:dsvm-functional]
-basepython = python3
 setenv =
   OS_TEST_PATH=./neutron_dynamic_routing/tests/functional
   OS_SUDO_TESTING=1
@@ -48,11 +46,9 @@ commands =
   stestr run {posargs}
 
 [testenv:releasenotes]
-basepython = python3
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:pep8]
-basepython = python3
 commands =
   flake8
   neutron-db-manage --subproject neutron-dynamic-routing --database-connection sqlite:// check_migration
@@ -60,7 +56,6 @@ commands =
   {[testenv:genpolicy]commands}
 
 [testenv:cover]
-basepython = python3
 setenv =
     {[testenv]setenv}
     PYTHON=coverage run --source neutron_dynamic_routing --parallel-mode
@@ -71,15 +66,12 @@ commands =
   coverage xml -o cover/coverage.xml
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:docs]
-basepython = python3
 commands = python setup.py build_sphinx
 
 [testenv:pdf-docs]
-basepython = python3
 envdir = {toxworkdir}/docs
 # deps = {[testenv:docs]deps}
 whitelist_externals =
@@ -128,7 +120,6 @@ commands = {toxinidir}/tools/generate_config_file_samples.sh
 commands = oslopolicy-sample-generator --config-file=etc/oslo-policy-generator/policy.conf
 
 [testenv:lower-constraints]
-basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt
@@ -140,14 +131,12 @@ deps =
 commands =
     pip install -q -e "git+https://opendev.org/openstack/neutron#egg=neutron"
 
-[testenv:py3-dev]
-basepython = python3
+[testenv:py-dev]
 commands =
     {[testenv:dev]commands}
     {[testenv]commands}
 
 [testenv:pep8-dev]
-basepython = python3
 deps =
     {[testenv]deps}
 commands =