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

Change-Id: I66486a38c92a08e38e962efd1ab950e1acca5659

doc/requirements.txt

@@ -0,0 +1,10 @@
+# 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.
+
+# this is required for the docs build jobs
+sphinx!=1.6.6,>=1.6.2 # BSD
+openstackdocstheme>=1.18.1 # Apache-2.0
+reno>=2.5.0 # Apache-2.0
+sphinxmark>=0.1.14 # Apache-2.0
+doc8>=0.6.0 # Apache-2.0

test-requirements.txt

@@ -7,10 +7,3 @@ pyasn1!=0.2.3,>=0.1.8 # BSD
 pyOpenSSL>=16.2.0 # Apache-2.0
 requests>=2.14.2 # Apache-2.0
 ndg-httpsclient>=0.4.2;python_version<'3.0' # BSD
-
-# this is required for the docs build jobs
-sphinx!=1.6.6,>=1.6.2 # BSD
-openstackdocstheme>=1.18.1 # Apache-2.0
-doc8>=0.6.0 # Apache-2.0
-reno>=2.5.0 # Apache-2.0
-sphinxmark>=0.1.14 # Apache-2.0

tox.ini

@@ -33,10 +33,11 @@ setenv =
 
 
 [testenv:docs]
+deps = -r{toxinidir}/doc/requirements.txt
 commands=
     bash -c "rm -rf doc/build"
     doc8 doc
-    python setup.py build_sphinx
+    sphinx-build -b html doc/source doc/build/html
 
 
 [doc8]
@@ -45,6 +46,7 @@ extensions = .rst
 
 
 [testenv:releasenotes]
+deps = -r{toxinidir}/doc/requirements.txt
 commands =
     sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
@@ -113,4 +115,3 @@ commands =
     {[testenv:bashate]commands}
     {[testenv:ansible-lint]commands}
     {[testenv:ansible-syntax]commands}
-    {[testenv:docs]commands}