Update docs build job for new documentation PTI jobs

openstack infra use a new way for building documents[1]

[1]:See http://lists.openstack.org/pipermail/openstack-dev/2017-December/125710.html for details

Change-Id: I8bdaa16706d0f4040b9c2e8ece639a59ffc52305

doc/requirements.txt

@@ -0,0 +1,3 @@
+oslo.config>=5.1.0 # Apache-2.0
+openstackdocstheme>=1.17.0 # Apache-2.0
+sphinx>=1.6.2 # BSD

test-requirements.txt

@@ -36,7 +36,3 @@ reno>=2.5.0 # Apache-2.0
 pysnmp>=4.2.3 # BSD
 osprofiler>=1.4.0 # Apache-2.0
 SQLAlchemy!=1.1.5,!=1.1.6,!=1.1.7,!=1.1.8,>=1.0.10 # MIT
-
-# Doc requirements
-openstackdocstheme>=1.17.0 # Apache-2.0
-sphinx>=1.6.2 # BSD

tox.ini

@@ -35,7 +35,11 @@ commands =
     coverage report
 
 [testenv:docs]
-commands = python setup.py build_sphinx
+deps =
+    -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
+        -r{toxinidir}/requirements.txt
+        -r{toxinidir}/doc/requirements.txt
+commands = sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:debug]
 commands = oslo_debug_helper {posargs}