Split requirements for documentation build

... because these are not required in tests. Also apply the global
constraints so that this is co-installable with the other components.

Change-Id: I210527b181339832c887ceec745cbd562a9f5256

doc/requirements.txt

@@ -0,0 +1,2 @@
+sphinx>=2.0.0,!=2.1.0 # BSD
+openstackdocstheme>=2.2.1 # Apache-2.0

requirements.txt

@@ -1,7 +1,3 @@
-# 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.
-
 pbr>=1.6 # Apache-2.0
 Babel>=1.3
 oslo.config>=3.14.0 # Apache-2.0

test-requirements.txt

@@ -1,14 +1,8 @@
-# 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.
-
 hacking>=3.0.1,<3.1.0 # Apache-2.0
 
 coverage>=3.6 # Apache-2.0
 stestr>=1.0.0 # Apache-2.0
 python-subunit>=0.0.18 # Apache-2.0/BSD
-sphinx>=2.0.0,!=2.1.0 # BSD
-openstackdocstheme>=2.2.1 # Apache-2.0
 oslotest>=1.10.0 # Apache-2.0
 testrepository>=0.0.18 # Apache-2.0/BSD
 testtools>=1.4.0 # MIT

tox.ini

@@ -14,6 +14,7 @@ setenv =
    OS_STDERR_CAPTURE=1
    OS_TEST_TIMEOUT=60
 deps =
+    -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
     -r{toxinidir}/requirements.txt
     -r{toxinidir}/test-requirements.txt
 commands = stestr --test-path ./tempest_stress/tests run {posargs}
@@ -42,14 +43,19 @@ commands =
     coverage xml -o cover/coverage.xml
 
 [testenv:docs]
+deps =
+    -r{toxinidir}/doc/requirements.txt
 commands = sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:pdf-docs]
 allowlist_externals =
-   make
+    make
+deps =
+    -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+    -r{toxinidir}/doc/requirements.txt
 commands =
-   sphinx-build -W -b latex doc/source doc/build/pdf
-   make -C doc/build/pdf
+    sphinx-build -W -b latex doc/source doc/build/pdf
+    make -C doc/build/pdf
 
 [testenv:debug]
 commands = oslo_debug_helper {posargs}