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

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

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

Change-Id: I54863f2301758dcd48de4ee73bcc8582e5036afa

.zuul.yaml

@@ -15,8 +15,7 @@
     templates:
       - openstack-cover-jobs
       - openstack-lower-constraints-jobs
-      - openstack-python-jobs
-      - openstack-python3-train-jobs
+      - openstack-python3-ussuri-jobs
       - check-requirements
       - openstackclient-plugin-jobs
       - publish-openstack-docs-pti

doc/requirements.txt

@@ -1,5 +1,4 @@
 openstackdocstheme>=1.18.1 # 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
+sphinx!=1.6.6,!=1.6.7,>=1.6.2 # BSD
 sphinxcontrib-httpdomain>=1.3.0  # BSD

releasenotes/notes/drop-python-2-7-73d3113c69d724d6.yaml

@@ -0,0 +1,5 @@
+---
+upgrade:
+  - |
+    Python 2.7 support has been dropped. The minimum version of Python now
+    supported by python-heatclient is Python 3.6.

setup.cfg

@@ -7,6 +7,7 @@ description-file =
 author = OpenStack
 author-email = openstack-discuss@lists.openstack.org
 home-page = https://docs.openstack.org/python-heatclient/latest
+python-requires = >=3.6
 classifier =
     Development Status :: 5 - Production/Stable
     Environment :: Console
@@ -16,11 +17,11 @@ 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
+    Programming Language :: Python :: 3 :: Only
+    Programming Language :: Python :: Implementation :: CPython
 
 [files]
 packages =
@@ -100,16 +101,6 @@ heatclient.resource.formatter.list =
     yaml = cliff.formatters.yaml_format:YAMLFormatter
     json = cliff.formatters.json_format:JSONFormatter
 
-[global]
-setup-hooks =
-    pbr.hooks.setup_hook
-
-[upload_sphinx]
-upload-dir = doc/build/html
-
-[wheel]
-universal = 1
-
 [extract_messages]
 keywords = _ gettext ngettext l_ lazy_gettext
 mapping_file = babel.cfg

setup.py

@@ -16,14 +16,6 @@
 # THIS FILE IS MANAGED BY THE GLOBAL REQUIREMENTS REPO - DO NOT EDIT
 import setuptools
 
-# In python < 2.7.4, a lazy loading of package `pbr` will break
-# setuptools if some other modules registered functions in `atexit`.
-# solution from: http://bugs.python.org/issue15881#msg170215
-try:
-    import multiprocessing  # noqa
-except ImportError:
-    pass
-
 setuptools.setup(
     setup_requires=['pbr>=2.0.0'],
     pbr=True)

tox.ini

@@ -1,13 +1,13 @@
 [tox]
-envlist = pypy,py27,py37,pep8
-minversion = 2.0
+envlist = pypy,py37,pep8
+ignore_basepython_conflict = true
+minversion = 3.1.0
 skipsdist = True
 
 [testenv]
+basepython = python3
 setenv = VIRTUAL_ENV={envdir}
-         CLIENT_NAME=python-heatclient
 usedevelop = True
-install_command = pip install {opts} {packages}
 deps =
        -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
        -r{toxinidir}/requirements.txt
@@ -17,24 +17,13 @@ commands = find . -type f -name "*.py[c|o]" -delete
 whitelist_externals = find
 
 [testenv:debug]
-basepython = python3
-commands = oslo_debug_helper -t heatclient/tests {posargs}
-
-[testenv:debug-py27]
-basepython = python2.7
-commands = oslo_debug_helper -t heatclient/tests {posargs}
-
-[testenv:debug-py35]
-basepython = python3.5
 commands = oslo_debug_helper -t heatclient/tests {posargs}
 
 [testenv:pep8]
-basepython = python3
 commands =
     flake8
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:functional]
@@ -44,7 +33,6 @@ setenv =
 passenv = OS_*
 
 [testenv:cover]
-basepython = python3
 setenv =
     PYTHON=coverage run --source heatclient --parallel-mode
 commands =
@@ -55,7 +43,6 @@ commands =
     coverage report
 
 [testenv:docs]
-basepython = python3
 deps =
        -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
        -r{toxinidir}/doc/requirements.txt
@@ -71,14 +58,12 @@ max-complexity=20
 import_exceptions = heatclient._i18n
 
 [testenv:releasenotes]
-basepython = python3
 deps =
        -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
        -r{toxinidir}/doc/requirements.txt
 commands = sphinx-build -a -E -W -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