Update docs building infra

This patch set migrates some of the file structure in compliance with
the Project Testing Interface (PTI) [0] for doc build in OpenStack-Infra.
See [1] for more details.

[0] https://governance.openstack.org/tc/reference/project-testing-interface.html#documentation
[1] http://lists.openstack.org/pipermail/openstack-dev/2017-November/124815.html

Change-Id: I5995ffd3a6821fd629e00351728c27a045a7c076
Signed-off-by: Tin Lam <tin@irrational.io>

doc/requirements.txt

@@ -0,0 +1,7 @@
+# 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>=1.6.2 # BSD
+sphinxcontrib-blockdiag>=1.1.0
+oslosphinx>=4.7.0 # Apache-2.0
+openstackdocstheme>=1.17.0 # Apache-2.0

test-requirements.txt

@@ -1,5 +0,0 @@
-sphinx>=1.5.1,!=1.6.1 # BSD
-sphinxcontrib-blockdiag>=1.1.0
-oslosphinx>=4.7.0 # Apache-2.0
-pbr>=3.0.0 # Apache-2.0
-openstackdocstheme>=1.16.0 # Apache-2.0

tox.ini

@@ -4,13 +4,18 @@ envlist = docs
 skipsdist = True
 
 [testenv]
-install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} -U {opts} {packages}
+install_command = pip install -U {opts} {packages}
 setenv = VIRTUAL_ENV={envdir}
-deps = -r{toxinidir}/test-requirements.txt
+deps = -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
 passenv = *_proxy *_PROXY
 
 [testenv:venv]
 commands = {posargs}
 
 [testenv:docs]
-commands = python setup.py build_sphinx
+deps = -r{toxinidir}/doc/requirements.txt
+commands =
+  bash -c "rm -rf doc/build"
+  python setup.py build_sphinx
+whitelist_externals =
+  bash