Remove Python 2 support from testing and gate jobs

tox:
- bumped tox minversion to 3.1.0 to get 'ignore_basepython_conflict'
- tox 'ignore_basepython_conflict' allows us to factor basepython=
  python3 to the [testenv] but override it when using '-e py37'
  (that way you actually get python 3.7 instead of whatever the system
  has for python3)
gate:
- adjusted tempest-dsvm-lvm-lio-barbican to use python 3 for devstack
- removed openstack-python-jobs template as these tests are covered
  in py3 by openstack-python3-ussuri-jobs
- dropped integrated-gate template as these tests are covered by the
  integrated-gate-storage template, which is already python3
- dropped tempest-full jobs as these are covered in py3 by tempest-
  integrated-storage
- changed openstack-tox-functional to openstack-tox-functional-py37
  and made it voting

The legacy-grenade-dsvm-cinder-mn-sub-* jobs are converted to py3
in a different patch, https://review.opendev.org/#/c/695787/

Left py2 requirements and did not adjust setup.cfg to require py3.
This prevents breakage for any projects still installing cinder under
py2.  These can be changed by a follow up patch in January.

Co-authored-by: Sean McGinnis <sean.mcginnis@gmail.com>
Co-authored-by: Brian Rosmaita <rosmaita.fossdev@gmail.com>

Closes-bug: #1853372

Change-Id: I376bd708ecc864f29c35b7225f875bb20a98cd3c

.zuul.yaml

@@ -1,12 +1,10 @@
 - project:
     templates:
       - openstack-lower-constraints-jobs
-      - openstack-python-jobs
       - openstack-python3-ussuri-jobs
       - publish-openstack-docs-pti
       - periodic-stable-jobs
       - check-requirements
-      - integrated-gate
       - integrated-gate-storage
       - release-notes-jobs-python3
     check:
@@ -24,6 +22,8 @@
               - ^contrib/block-box.*$
               - ^doc/.*$
               - ^releasenotes/.*$
+        - openstack-tox-functional-py37:
+            irrelevant-files: *functional-irrelevant-files
         - cinder-rally-task:
             voting: false
         - openstack-tox-pylint:
@@ -48,9 +48,6 @@
               - ^setup.cfg$
               - ^tools/.*$
               - ^tox.ini$
-        - openstack-tox-functional:
-            voting: false
-            irrelevant-files: *functional-irrelevant-files
         - legacy-grenade-dsvm-cinder-mn-sub-volbak:
             irrelevant-files: *gate-irrelevant-files
         - legacy-tempest-dsvm-lvm-multibackend:
@@ -61,8 +58,6 @@
             irrelevant-files: *gate-irrelevant-files
         - tempest-slow-py3:
             irrelevant-files: *gate-irrelevant-files
-        - tempest-full:
-            irrelevant-files: *gate-irrelevant-files
         - tempest-integrated-storage:
             irrelevant-files: *gate-irrelevant-files
         - grenade-py3:
@@ -73,8 +68,6 @@
       jobs:
         - legacy-grenade-dsvm-cinder-mn-sub-volbak:
             irrelevant-files: *gate-irrelevant-files
-        - tempest-full:
-            irrelevant-files: *gate-irrelevant-files
         - tempest-integrated-storage:
             irrelevant-files: *gate-irrelevant-files
         - grenade-py3:

playbooks/legacy/cinder-tempest-dsvm-lvm-lio-barbican/run.yaml

@@ -54,6 +54,7 @@
               # pip for stable branches.
               export DEVSTACK_PROJECT_FROM_GIT=os-brick
           fi
+          export DEVSTACK_GATE_USE_PYTHON3=True
           export DEVSTACK_GATE_TEMPEST=1
           export DEVSTACK_GATE_TEMPEST_ALL_PLUGINS=1
           # As we are setting DEVSTACK_GATE_TEMPEST_ALL_PLUGINS, we need to add

releasenotes/notes/drop-py2-377a91a5b66165ab.yaml

@@ -0,0 +1,6 @@
+---
+upgrade:
+  - |
+    Python 2.7 support has been dropped. The last release of Cinder to support
+    py2.7 is OpenStack Train. The minimum version of Python now supported by
+    Cinder 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

@@ -1,10 +1,15 @@
 [tox]
-minversion = 2.5
+minversion = 3.1.0
 skipsdist = True
 skip_missing_interpreters = true
-envlist = py37,py27,compliance,pep8
+# python runtimes: https://governance.openstack.org/tc/reference/runtimes/ussuri.html
+envlist = py37,py36,compliance,pep8
+# this allows tox to infer the base python from the environment name
+# and override any basepython configured in this file
+ignore_basepython_conflict=true
 
 [testenv]
+basepython = python3
 setenv = VIRTUAL_ENV={envdir}
          PYTHONWARNINGS=default::DeprecationWarning
          OS_STDOUT_CAPTURE=1
@@ -33,7 +38,6 @@ whitelist_externals =
 passenv = *_proxy *_PROXY
 
 [testenv:api-ref]
-basepython = python3
 whitelist_externals = rm
 deps = {[testenv:docs]deps}
 commands =
@@ -41,7 +45,6 @@ commands =
   sphinx-build -W -b html -d api-ref/build/doctrees api-ref/source api-ref/build/html/
 
 [testenv:releasenotes]
-basepython = python3
 deps = {[testenv:docs]deps}
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
@@ -68,12 +71,10 @@ commands =
   stestr slowest
 
 [testenv:compliance]
-basepython = python3
 setenv =
   OS_TEST_PATH = ./cinder/tests/compliance
 
 [testenv:pep8]
-basepython = python3
 commands =
   flake8 {posargs} .
   doc8
@@ -81,7 +82,6 @@ commands =
   {toxinidir}/tools/check_exec.py {toxinidir}/cinder {toxinidir}/doc/source/ {toxinidir}/releasenotes/notes
 
 [testenv:fast8]
-basepython = python3
 # Use same environment directory as pep8 env to save space and install time
 envdir = {toxworkdir}/pep8
 commands =
@@ -89,7 +89,6 @@ commands =
 passenv = FAST8_NUM_COMMITS
 
 [testenv:pylint]
-basepython = python3
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
        pylint==2.3.0
@@ -99,7 +98,6 @@ commands =
 [testenv:cover]
 # Also do not run test_coverage_ext tests while gathering coverage as those
 # tests conflict with coverage.
-basepython = python3
 setenv =
     {[testenv]setenv}
     PYTHON=coverage run --source cinder --parallel-mode
@@ -110,28 +108,23 @@ commands =
     coverage xml -o cover/coverage.xml
 
 [testenv:genconfig]
-basepython = python3
 sitepackages = False
 envdir = {toxworkdir}/pep8
 commands = oslo-config-generator --config-file=tools/config/cinder-config-generator.conf
 
 
 [testenv:genpolicy]
-basepython = python3
 commands = oslopolicy-sample-generator --config-file=tools/config/cinder-policy-generator.conf
 
 [testenv:genopts]
-basepython = python3
 sitepackages = False
 envdir = {toxworkdir}/pep8
 commands = python tools/config/generate_cinder_opts.py
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:docs]
-basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/doc/requirements.txt
@@ -142,7 +135,6 @@ commands =
 whitelist_externals = rm
 
 [testenv:pdf-docs]
-basepython = python3
 deps = {[testenv:docs]deps}
 commands =
   rm -fr doc/source/contributor/api/
@@ -154,18 +146,15 @@ whitelist_externals =
   rm
 
 [testenv:gendriverlist]
-basepython = python3
 sitepackages = False
 envdir = {toxworkdir}/venv
 commands = python {toxinidir}/tools/generate_driver_list.py
 
 [testenv:bandit]
-basepython = python3
 deps = -r{toxinidir}/test-requirements.txt
 commands = bandit -r cinder -n5 -x cinder/tests/* -ll
 
 [testenv:bandit-baseline]
-basepython = python3
 envdir = {toxworkdir}/bandit
 commands = bandit-baseline -r cinder -n5 -x cinder/tests/* -ii -ll
 
@@ -176,7 +165,6 @@ commands = bandit-baseline -r cinder -n5 -x cinder/tests/* -ii -ll
 # separately, outside of the requirements files, and develop mode disabled
 # explicitly to avoid unnecessarily installing the checked-out repo too (this
 # further relies on "tox.skipsdist = True" above).
-basepython = python3
 deps = bindep
 commands = bindep test
 usedevelop = False
@@ -211,12 +199,10 @@ local-check-factory = cinder.tests.hacking.checks.factory
 import_exceptions = cinder.i18n
 
 [doc8]
-
 ignore-path=.tox,*.egg-info,doc/src/api,doc/source/drivers.rst,doc/build,.eggs/*/EGG-INFO/*.txt,doc/source/configuration/tables,./*.txt
 extension=.txt,.rst,.inc
 
 [testenv:lower-constraints]
-basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt