[ussuri][goal] Finish dropping python 2.7 support

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

This change cleans up:
* remove old requirements
* remove universal wheel building, we don't need this for py3
* cleanup setup.py
* tox.ini: move basepython around; remove install_command since the
  default is fine and constraints should be in deps; add
  ignore_basepython_conflict

Change-Id: Ife0a696ca62be21d3d93c5d8279a412578f62697

doc/requirements.txt

@@ -4,8 +4,7 @@
 
 openstackdocstheme>=1.20.0 # Apache-2.0
 os-api-ref>=1.4.0 # Apache-2.0
-sphinx>=1.8.0,!=2.1.0;python_version>='3.4' # BSD
+sphinx>=1.8.0,!=2.1.0 # BSD
-sphinx>=1.8.0,<2.0.0;python_version=='2.7' # BSD
 reno>=2.5.0 # Apache-2.0
 sphinxcontrib-apidoc>=0.2.0 # BSD
 sphinxcontrib-httpdomain>=1.3.0 # BSD

setup.cfg

@@ -6,6 +6,7 @@ description-file =
 author = OpenStack
 author-email = openstack-discuss@lists.openstack.org
 home-page = https://docs.openstack.org/heat/latest/
+python-requires = >=3.6
 classifier =
     Environment :: OpenStack
     Intended Audience :: Information Technology
@@ -198,10 +199,6 @@ heat.templates =
    heat_template_version.2018-08-31 = heat.engine.hot.template:HOTemplate20180831
    heat_template_version.rocky = heat.engine.hot.template:HOTemplate20180831
 
-[global]
-setup-hooks =
-    pbr.hooks.setup_hook
-
 [compile_catalog]
 directory = heat/locale
 domain = heat

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

@@ -1,15 +1,17 @@
 [tox]
 envlist = py36,py37,pep8
-minversion = 1.6
+ignore_basepython_conflict = True
+minversion = 3.1.0
 skipsdist = True
 
 [testenv]
+basepython = python3
 setenv = VIRTUAL_ENV={envdir}
          PYTHONWARNINGS=default::DeprecationWarning
          OS_TEST_PATH=heat/tests
 usedevelop = True
-install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master} {opts} {packages}
+deps = -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
-deps = -r{toxinidir}/requirements.txt
+       -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 commands =
   stestr run {posargs}
@@ -18,7 +20,6 @@ commands =
 passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 
 [testenv:pep8]
-basepython = python3
 commands =
     flake8 heat bin/heat-api bin/heat-api-cfn bin/heat-engine bin/heat-manage contrib heat_integrationtests doc/source
     python tools/custom_guidelines.py --exclude heat/engine/resources/aws
@@ -39,11 +40,9 @@ commands =
     doc8 {posargs}
 
 [testenv:venv]
-basepython = python3
 commands = {posargs}
 
 [testenv:cover]
-basepython = python3
 setenv =
   PYTHON=coverage run --source heat --parallel-mode
 commands =
@@ -55,7 +54,6 @@ commands =
   coverage report
 
 [testenv:docs]
-basepython = python3
 whitelist_externals =
   rm
 deps = -r{toxinidir}/doc/requirements.txt
@@ -64,7 +62,6 @@ commands =
   sphinx-build -W --keep-going -b html doc/source doc/build/html
 
 [testenv:pdf-docs]
-basepython = python3
 deps = {[testenv:docs]deps}
 whitelist_externals =
   make
@@ -73,7 +70,6 @@ commands =
   make -C doc/build/pdf
 
 [testenv:api-ref]
-basepython = python3
 # This environment is called from CI scripts to test and publish
 # the API Ref to docs.openstack.org.
 deps = -r{toxinidir}/doc/requirements.txt
@@ -83,19 +79,18 @@ commands =
   sphinx-build -W --keep-going -b html -d api-ref/build/doctrees api-ref/source api-ref/build/html
 
 [testenv:genconfig]
-basepython = python3
 commands =
     oslo-config-generator --config-file=config-generator.conf
     oslo-config-generator --config-file=heat_integrationtests/config-generator.conf
 
 [testenv:genpolicy]
-basepython = python3
 commands =
     oslopolicy-sample-generator --config-file etc/heat/heat-policy-generator.conf
 
 [testenv:bandit]
-basepython = python3
+deps =
-deps = -r{toxinidir}/test-requirements.txt
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -r{toxinidir}/test-requirements.txt
 # The following bandit tests are being skipped:
 # B101: Test for use of assert
 # B104: Test for binding to all interfaces
@@ -125,11 +120,9 @@ import_exceptions = heat.common.i18n
 local-check-factory = heat.hacking.checks.factory
 
 [testenv:debug]
-basepython = python3
 commands = oslo_debug_helper {posargs}
 
 [testenv:releasenotes]
-basepython = python3
 whitelist_externals =
   rm
 deps = -r{toxinidir}/doc/requirements.txt
@@ -138,7 +131,6 @@ commands =
   sphinx-build -a -E -W -d releasenotes/build/doctrees --keep-going -b html releasenotes/source releasenotes/build/html
 
 [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
@@ -150,7 +142,6 @@ commands = bindep test
 usedevelop = False
 
 [testenv:lower-constraints]
-basepython = python3
 install_command = pip install {opts} {packages}
 deps =
   -c{toxinidir}/lower-constraints.txt