Drop python 2.7 support and testing

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

Tacker 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://review.opendev.org/#/c/691178/

Depends-On: https://review.opendev.org/#/c/693631/

Change-Id: I3bf7be13f69837a0c2b9d62d10b21dce0fd0fe76

.zuul.yaml

@@ -25,7 +25,7 @@
           - compute1
 
 - job:
-    name: tacker-functional-devstack-multinode
+    name: tacker-functional-devstack-multinode-python3
     parent: devstack
     description: |
       Base multinodes job for devstack-based functional tests
@@ -109,27 +109,15 @@
           horizon: false
           tls-proxy: false
 
-- job:
-    name: tacker-functional-devstack-multinode-python3
-    parent: tacker-functional-devstack-multinode
-    description: |
-      Run tacker functional tests using python3 against a master devstack
-    vars:
-      tacker_environment:
-        TACKER_TOX_PYTHON: python3
-
 - project:
     templates:
       - check-requirements
       - openstack-cover-jobs
       - openstack-lower-constraints-jobs
-      - openstack-python-jobs
       - openstack-python3-ussuri-jobs
       - publish-openstack-docs-pti
       - release-notes-jobs-python3
     check:
       jobs:
-        - tacker-functional-devstack-multinode:
-            voting: false
         - tacker-functional-devstack-multinode-python3:
             voting: false

doc/requirements.txt

@@ -1,7 +1,6 @@
 # The order of packages is significant, because pip processes them in the order
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
-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,!=2.1.0,>=1.6.2;python_version>='3.4'  # BSD
 sphinxcontrib-apidoc>=0.2.0  # BSD
 openstackdocstheme>=1.20.0 # Apache-2.0

releasenotes/notes/drop-py-2-7-8db9ceef15903295.yaml

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

setup.cfg

@@ -13,9 +13,7 @@ classifier =
     License :: OSI Approved :: Apache Software License
     Operating System :: POSIX :: Linux
     Programming Language :: Python
-    Programming Language :: Python :: 2
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
 

tox.ini

@@ -1,10 +1,11 @@
 [tox]
-envlist = py37,py36,py27,pep8,docs
-minversion = 2.0
+envlist = py37,py36,pep8,docs
+minversion = 3.1.1
 skipsdist = True
+ignore_basepython_conflict = True
 
 [testenv]
-basepython = {env:TACKER_TOX_PYTHON:python2}
+basepython = python3
 setenv = VIRTUAL_ENV={envdir}
          OS_LOG_CAPTURE={env:OS_LOG_CAPTURE:true}
          OS_STDOUT_CAPTURE={env:OS_STDOUT_CAPTURE:true}
@@ -25,7 +26,6 @@ commands =
   stestr --test-path=./tacker/tests/functional run --slowest {posargs}
 
 [testenv:dsvm-functional]
-basepython = python2.7
 setenv = {[testenv]setenv}
 
 commands =
@@ -34,10 +34,6 @@ commands =
 [testenv:debug]
 commands = oslo_debug_helper {posargs}
 
-[testenv:debug-py27]
-basepython = python2.7
-commands = oslo_debug_helper {posargs}
-
 [testenv:debug-py36]
 basepython = python3.6
 commands = oslo_debug_helper {posargs}
@@ -45,7 +41,6 @@ commands = oslo_debug_helper {posargs}
 [testenv:pep8]
 deps = -r{toxinidir}/doc/requirements.txt
        -r{toxinidir}/test-requirements.txt
-basepython = python2.7
 commands =
   flake8
   doc8 -e .rst doc/source/ CONTRIBUTING.rst HACKING.rst README.rst TESTING.rst
@@ -113,7 +108,6 @@ deps =
   -r{toxinidir}/requirements.txt
 
 [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