Follow the new PTI for document build

For compliance with the Project Testing Interface as described in:
https://governance.openstack.org/tc/reference/project-testing-interface.html

For more details information, please refer to:
http://lists.openstack.org/pipermail/openstack-dev/2017-December/125710.html

Change-Id: I4dd494a46011aa8547f52b442f9cba4d402fb91a

doc/requirements.txt

@@ -0,0 +1,5 @@
+sphinx!=1.6.6,!=1.6.7,>=1.6.2 # BSD
+sphinxcontrib-httpdomain>=1.3.0 # BSD
+sphinxcontrib-pecanwsme>=0.8.0 # Apache-2.0
+openstackdocstheme>=1.18.1 # Apache-2.0
+reno>=2.5.0 # Apache-2.0

setup.cfg

@@ -24,15 +24,6 @@ packages =
     mistral
     mistral_tempest_tests
 
-[build_sphinx]
-source-dir = doc/source
-build-dir = doc/build
-all_files = 1
-warning-is-error = 1
-
-[upload_sphinx]
-upload-dir = doc/build/html
-
 [entry_points]
 console_scripts =
     mistral-server = mistral.cmd.launch:main

test-requirements.txt

@@ -19,12 +19,7 @@ oslo.policy>=1.30.0 # Apache-2.0
 osprofiler>=1.4.0 # Apache-2.0
 os-api-ref>=1.4.0 # Apache-2.0
 oauthlib>=0.6.2 # BSD
-reno>=2.5.0 # Apache-2.0
 requests-mock>=1.2.0 # Apache-2.0
-sphinx!=1.6.6,!=1.6.7,>=1.6.2 # BSD
-sphinxcontrib-httpdomain>=1.3.0 # BSD
-sphinxcontrib-pecanwsme>=0.8.0 # Apache-2.0
-openstackdocstheme>=1.18.1 # Apache-2.0
 tooz>=1.58.0 # Apache-2.0
 tempest>=17.1.0 # Apache-2.0
 stestr>=2.0.0 # Apache-2.0

tox.ini

@@ -73,11 +73,12 @@ commands = {posargs}
 
 #set PYTHONHASHSEED=0 to prevent wsmeext.sphinxext from randomly failing.
 [testenv:docs]
-basepython = python2.7
+basepython = python3
+deps = -r{toxinidir}/doc/requirements.txt
 setenv = PYTHONHASHSEED=0
 commands =
   rm -rf doc/build
-  sphinx-build -b html doc/source doc/build/html
+  sphinx-build -E -W -b html doc/source doc/build/html
 
 [testenv:releasenotes]
 basepython = python3