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

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

sahara-tests 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

Noteworthy change:
- run sahara-scenario with Python 3 also against the older releases
  (up to rocky) which are Xenial-based.
- on the other hand, make sure that the jobs use a Python 2
  devstack environment when deploying the pre-Ussuri branches;
- add the missing scenario-test jobs for stein and train.

Co-Authored-By: Luigi Toscano <ltoscano@redhat.com>
Change-Id: I3666a9ed9047f7c6a358e40d2f7a1d1103f8563b

.zuul.yaml

@@ -3,8 +3,7 @@
       - openstack-python-jobs
       - publish-openstack-docs-pti
       - openstack-python35-jobs
-      - openstack-python36-jobs
-      - openstack-python37-jobs
+      - openstack-python3-ussuri-jobs
       - release-notes-jobs-python3
     check:
       jobs:
@@ -14,9 +13,10 @@
             voting: false
         - sahara-tests-scenario
         - sahara-tests-scenario-v2
-        - sahara-tests-scenario-py3
         - sahara-tests-tempest
         - sahara-tests-tempest-v2
+        - sahara-tests-scenario-train
+        - sahara-tests-scenario-stein
         - sahara-tests-scenario-rocky
         - sahara-tests-scenario-queens
         - sahara-tests-scenario-pike
@@ -25,13 +25,11 @@
       jobs:
         - sahara-tests-scenario
         - sahara-tests-scenario-v2
-        - sahara-tests-scenario-py3
         - sahara-tests-tempest
         - sahara-tests-tempest-v2
     experimental:
       jobs:
         - sahara-tests-scenario-multinode-spark
-        - sahara-tests-scenario-multinode-spark-py3
 
 - job:
     name: sahara-tests-tempest
@@ -55,6 +53,7 @@
       devstack_localrc:
         IMAGE_URLS: https://cloud-images.ubuntu.com/xenial/current/xenial-server-cloudimg-amd64-disk1.img
         TEMPEST_PLUGINS: /opt/stack/sahara-tests
+        USE_PYTHON3: True
       devstack_local_conf:
         test-config:
           $TEMPEST_CONFIG:
@@ -109,12 +108,25 @@
       - stable/pike
       - stable/queens
     vars:
+      devstack_localrc:
+        USE_PYTHON3: 'False'
       devstack_local_conf:
         test-config:
           $TEMPEST_CONFIG:
             data-processing-feature-enabled:
               s3: 'False'
 
+# variant for pre-Ussuri branches (Python 2 by default)
+- job:
+    name: sahara-tests-tempest
+    branches:
+      - stable/rocky
+      - stable/stein
+      - stable/train
+    vars:
+      devstack_localrc:
+        USE_PYTHON3: 'False'
+
 - job:
     name: sahara-tests-scenario
     description: |
@@ -155,6 +167,7 @@
         # required to contain (almost any) custom-built image
         SWIFT_LOOPBACK_DISK_SIZE: 8G
         SWIFT_MAX_FILE_SIZE: 8589934592
+        USE_PYTHON3: True
       devstack_local_conf:
         post-config:
           $SAHARA_CONF_FILE:
@@ -179,26 +192,48 @@
     vars:
       sahara_scenario_use_api_v2: True
 
+
+# pre-Ussuri scenario tests: devstack must use python 2,
+# but sahara-scenario can use python 3.
+- job:
+    name: sahara-tests-scenario-train
+    parent: sahara-tests-scenario
+    override-checkout: stable/train
+    vars:
+      devstack_localrc:
+        USE_PYTHON3: 'False'
+
+- job:
+    name: sahara-tests-scenario-stein
+    parent: sahara-tests-scenario
+    override-checkout: stable/stein
+    vars:
+      devstack_localrc:
+        USE_PYTHON3: 'False'
+
 - job:
     name: sahara-tests-scenario-rocky
     parent: sahara-tests-scenario
     override-checkout: stable/rocky
     vars:
-      sahara_scenario_tox_env: venv-py2
+      devstack_localrc:
+        USE_PYTHON3: 'False'
 
 - job:
     name: sahara-tests-scenario-queens
     parent: sahara-tests-scenario
     override-checkout: stable/queens
     vars:
-      sahara_scenario_tox_env: venv-py2
+      devstack_localrc:
+        USE_PYTHON3: 'False'
 
 - job:
     name: sahara-tests-scenario-pike
     parent: sahara-tests-scenario
     override-checkout: stable/pike
     vars:
-      sahara_scenario_tox_env: venv-py2
+      devstack_localrc:
+        USE_PYTHON3: 'False'
 
 - job:
     name: sahara-tests-scenario-modwsgi
@@ -240,6 +275,17 @@
         s-proxy: false
       sahara_enable_s3: True
 
+- job:
+    name: sahara-tests-scenario-py3
+    description: |
+      Run scenario tests on a Sahara deployment based on Python 3.
+      Required by some pre-Ussuri branches of sahara, which also
+      needs swift (not fully ported to Python 3 at the time).
+    parent: sahara-tests-scenario-radosgw
+    vars:
+      devstack_localrc:
+        USE_PYTHON3: 'True'
+
 - job:
     name: sahara-tests-scenario-multinode-spark
     description: |
@@ -259,21 +305,3 @@
           disk: 20
           vcpus: 1
           ephemeral: 0
-
-- job:
-    name: sahara-tests-scenario-py3
-    description: |
-      Run scenario tests on a Sahara deployment based on Python 3.
-    parent: sahara-tests-scenario-radosgw
-    vars:
-      devstack_localrc:
-        USE_PYTHON3: 'True'
-
-- job:
-    name: sahara-tests-scenario-multinode-spark-py3
-    description: |
-      Run scenario tests on Spark on a multinode Python 3 Sahara deployment.
-    parent: sahara-tests-scenario-multinode-spark
-    vars:
-      devstack_localrc:
-        USE_PYTHON3: 'True'

releasenotes/notes/drop-py-2-7-188a5c85a436ee4f.yaml

@@ -0,0 +1,7 @@
+---
+upgrade:
+  - |
+    Python 2.7 support has been dropped. Last release of sahara-tests
+    to support python 2.7 is 0.9.1, the first version that can be used
+    with OpenStack Train.
+    The minimum version of Python now supported by sahara-tests is Python 3.5.

setup.cfg

@@ -5,8 +5,10 @@ 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 :: 3.5
+    Programming Language :: Python :: 3.6
+    Programming Language :: Python :: 3.7
     Environment :: OpenStack
     Intended Audience :: Information Technology
     Intended Audience :: System Administrators

tox.ini

@@ -1,9 +1,13 @@
 [tox]
-envlist = py37,py36,py35,py27,pep8,releasenotes
+envlist = py37,py36,py35,pep8,releasenotes
 minversion = 2.0
 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 -U {opts} {packages}
 setenv =
@@ -20,19 +24,12 @@ basepython = python3
 commands = {posargs}
 passenv = OS_*
 
-[testenv:venv-py2]
-basepython = python2
-commands = {posargs}
-passenv = OS_*
-
 [testenv:cover]
-basepython = python3
 setenv =
     PACKAGE_NAME=sahara_tests
 commands = {toxinidir}/tools/cover.sh {posargs}
 
 [testenv:docs]
-basepython = python3
 deps =
     -r{toxinidir}/doc/requirements.txt
 commands =
@@ -45,12 +42,10 @@ whitelist_externals =
 downloadcache = ~/cache/pip
 
 [testenv:pylint]
-basepython = python3
 setenv = VIRTUAL_ENV={envdir}
 commands = bash tools/lintstack.sh
 
 [testenv:pep8]
-basepython = python3
 deps =
     -r{toxinidir}/requirements.txt
     -r{toxinidir}/doc/requirements.txt
@@ -66,7 +61,6 @@ commands =
 whitelist_externals = bash
 
 [testenv:releasenotes]
-basepython = python3
 deps =
     -r{toxinidir}/doc/requirements.txt
 commands =