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

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

sahara 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

Other required Sahara changes:
- port the image building job to CentOS 8, and thus Python 3.

Depends-On: https://review.opendev.org/#/c/693631/
Depends-On: https://review.opendev.org/#/c/694699/
Change-Id: I30485a9933d38db76c031c6e760598c4e47123fc

.zuul.yaml

@@ -1,7 +1,6 @@
 - project:
     templates:
       - openstack-lower-constraints-jobs
-      - openstack-python-jobs
       - openstack-python3-ussuri-jobs
       - periodic-stable-jobs
       - publish-openstack-docs-pti
@@ -90,10 +89,12 @@
       - openstack/openstack-ansible-os_sahara
     vars:
       osa_test_repo: openstack/openstack-ansible-os_sahara
+      devstack_localrc:
+        USE_PYTHON3: True
 
 - job:
     name: sahara-buildimages-base
-    nodeset: centos-7
+    nodeset: centos-8
     vars:
       sahara_src_dir: src/opendev.org/openstack/sahara
     run: playbooks/buildimages/run.yaml

bindep.txt

@@ -25,6 +25,6 @@ postgresql-devel [platform:rpm]
 # command.
 python-guestfs [platform:dpkg]
 libguestfs-xfs [platform:dpkg]
-python-libguestfs [platform:rpm]
+python3-libguestfs [platform:rpm]
 libguestfs-xfs [platform:redhat]
 xfsprogs [platform:suse]

releasenotes/notes/drop-py-2-7-bc282e43b26fbf17.yaml

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

setup.cfg

@@ -5,8 +5,6 @@ description-file = README.rst
 license = Apache Software License
 classifiers =
     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 +1,13 @@
 [tox]
-envlist = py27,py37,pep8,genpolicy
+envlist = py37,pep8,genpolicy
 minversion = 1.6
 skipsdist = True
+# 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
 usedevelop = True
 install_command = pip install {opts} {packages}
 setenv =
@@ -17,15 +21,10 @@ commands = stestr run {posargs}
 passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 
 [testenv:cover]
-basepython = python3
 setenv =
     PACKAGE_NAME=sahara
 commands = {toxinidir}/tools/cover.sh {posargs}
 
-[testenv:debug-py27]
-basepython = python2.7
-commands = oslo_debug_helper -t sahara/tests/unit {posargs}
-
 [testenv:debug-py36]
 basepython = python3.6
 commands = oslo_debug_helper -t sahara/tests/unit {posargs}
@@ -35,7 +34,6 @@ basepython = python3.7
 commands = oslo_debug_helper -t sahara/tests/unit {posargs}
 
 [testenv:pep8]
-basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/requirements.txt
@@ -50,11 +48,9 @@ commands =
     bandit -c bandit.yaml -r sahara -n5 -p sahara_default -x tests
 
 [testenv:genpolicy]
-basepython = python3
 commands = oslopolicy-sample-generator --config-file tools/config/sahara-policy-generator.conf
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:images]
@@ -62,7 +58,6 @@ sitepackages = True
 commands = {posargs}
 
 [testenv:docs]
-basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/doc/requirements.txt
@@ -76,7 +71,6 @@ commands =
 whitelist_externals = rm
 
 [testenv:api-ref]
-basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/doc/requirements.txt
@@ -88,18 +82,15 @@ whitelist_externals = rm
 
 
 [testenv:pylint]
-basepython = python3
 setenv = VIRTUAL_ENV={envdir}
 commands = bash tools/lintstack.sh
 
 [testenv:genconfig]
-basepython = python3
 commands =
     oslo-config-generator --config-file tools/config/config-generator.sahara.conf \
     --output-file etc/sahara/sahara.conf.sample
 
 [testenv:releasenotes]
-basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/doc/requirements.txt
@@ -109,7 +100,6 @@ commands =
 whitelist_externals = rm
 
 [testenv:debug]
-basepython = python3
 # It runs tests from the specified dir (default is sahara/tests)
 # in interactive mode, so, you could use pbr for tests debug.
 # Example usage: tox -e debug -- -t sahara/tests/unit some.test.path
@@ -117,7 +107,6 @@ basepython = python3
 commands = oslo_debug_helper -t sahara/tests/unit {posargs}
 
 [testenv:bandit]
-basepython = python3
 deps = -r{toxinidir}/test-requirements.txt
 commands = bandit -c bandit.yaml -r sahara -n5 -p sahara_default -x tests
 
@@ -145,7 +134,6 @@ import_exceptions = sahara.i18n
 local-check-factory = sahara.utils.hacking.checks.factory
 
 [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
@@ -154,7 +142,6 @@ deps = bindep
 commands = bindep test
 
 [testenv:lower-constraints]
-basepython = python3
 deps =
   -c{toxinidir}/lower-constraints.txt
   -r{toxinidir}/test-requirements.txt