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

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

Kuryr 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: I6c14fa3b0c3a19b5f50f5d78a43ba060c10de914

.zuul.yaml

@@ -2,7 +2,6 @@
     templates:
       - openstack-cover-jobs
       - openstack-lower-constraints-jobs
-      - openstack-python-jobs
       - openstack-python3-ussuri-jobs
       - release-notes-jobs-python3
       - publish-openstack-docs-pti

doc/requirements.txt

@@ -1,4 +1,3 @@
 openstackdocstheme>=1.20.0 # 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,>=1.6.2;python_version>='3.4'  # BSD

releasenotes/notes/drop-py-2-7-08ca2f91d31c9807.yaml

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

requirements.txt

@@ -3,7 +3,6 @@
 # process, which may cause wedges in the gate later.
 
 Babel!=2.4.0,>=2.3.4 # BSD
-ipaddress>=1.0.16;python_version<'3.3' # PSF
 keystoneauth1>=3.4.0 # Apache-2.0
 neutron-lib>=1.13.0 # Apache-2.0
 oslo.concurrency>=3.25.0 # Apache-2.0

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 = 2.3.1
-envlist = py27,py37,pep8
+envlist = py37,pep8
 skipsdist = True
 
 [testenv]
+basepython = python3
 # Note the hash seed is set to 0 until neutron can be tested with a
 # random hash seed successfully.
 setenv = VIRTUAL_ENV={envdir}
@@ -22,15 +23,10 @@ commands = find . -type f -name "*.py[c|o]" -delete
            stestr slowest
 
 [testenv:fullstack]
-basepython = python2.7
+basepython = python3.6
 setenv = OS_TEST_PATH=./kuryr/tests/fullstack
 
 [testenv:debug]
-basepython = python3
-commands = oslo_debug_helper -t kuryr/tests {posargs}
-
-[testenv:debug-py27]
-basepython = python2.7
 commands = oslo_debug_helper -t kuryr/tests {posargs}
 
 [testenv:debug-py35]
@@ -38,15 +34,12 @@ basepython = python3.5
 commands = oslo_debug_helper -t kuryr/tests {posargs}
 
 [testenv:pep8]
-basepython = python3
 commands = flake8
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 setenv =
     VIRTUAL_ENV={envdir}
     PYTHON=coverage run --source kuryr --parallel-mode
@@ -58,7 +51,6 @@ commands =
     coverage report
 
 [testenv:docs]
-basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands = sphinx-build -a -E -W -d doc/build/doctrees -b html doc/source doc/build/html
 
@@ -74,7 +66,6 @@ show-source = true
 exclude = .venv,.git,.tox,dist,doc,*lib/python*,*egg,build,tools,.ropeproject,rally-scenarios,releasenotes
 
 [testenv:pylint]
-basepython = python3
 deps =
   {[testenv]deps}
   pylint
@@ -86,15 +77,12 @@ import_exceptions = neutron.i18n
 local-check-factory = neutron_lib.hacking.checks.factory
 
 [testenv:genconfig]
-basepython = python3
 commands = oslo-config-generator --config-file=etc/kuryr-config-generator.conf
 
 [testenv:releasenotes]
-basepython = python3
 commands = sphinx-build -a -W -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