add lower-constraints job

Create a tox environment for running the unit tests against the lower
bounds of the dependencies.

Create a lower-constraints.txt to be used to enforce the lower bounds
in those tests.

Add openstack-tox-lower-constraints job to the zuul configuration.

See http://lists.openstack.org/pipermail/openstack-dev/2018-March/128352.html
for more details.

Change-Id: Ie84cfebdf35828c961a86769cef505eb1368efcb
Depends-On: https://review.openstack.org/555034
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

.zuul.yaml

@@ -0,0 +1,7 @@
+- project:
+    check:
+      jobs:
+        - openstack-tox-lower-constraints
+    gate:
+      jobs:
+        - openstack-tox-lower-constraints

lower-constraints.txt

@@ -0,0 +1,105 @@
+alabaster==0.7.10
+alembic==0.9.8
+amqp==2.2.2
+appdirs==1.4.3
+Babel==2.5.3
+cachetools==2.0.1
+certifi==2018.1.18
+chardet==3.0.4
+click==6.7
+contextlib2==0.5.5
+coverage==4.5.1
+debtcollector==1.19.0
+docutils==0.14
+dogpile.cache==0.6.5
+dulwich==0.19.0
+enum-compat==0.0.2
+eventlet==0.20.0
+extras==1.0.0
+fasteners==0.14.1
+fixtures==3.0.0
+flake8==2.5.5
+Flask==0.12.2
+flask-keystone==0.2
+flask-oslolog==0.1
+Flask-SQLAlchemy==2.3.2
+futurist==1.6.0
+greenlet==0.4.13
+hacking==0.12.0
+idna==2.6
+imagesize==1.0.0
+iso8601==0.1.12
+itsdangerous==0.24
+Jinja2==2.10
+keystoneauth1==3.4.0
+keystonemiddleware==4.21.0
+kombu==4.1.0
+linecache2==1.0.0
+Mako==1.0.7
+MarkupSafe==1.0
+mccabe==0.2.1
+mock==2.0.0
+monotonic==1.4
+mox3==0.25.0
+msgpack==0.5.6
+netaddr==0.7.19
+netifaces==0.10.6
+os-client-config==1.29.0
+oslo.cache==1.29.0
+oslo.concurrency==3.26.0
+oslo.config==5.2.0
+oslo.context==2.20.0
+oslo.i18n==3.20.0
+oslo.log==3.37.0
+oslo.messaging==5.36.0
+oslo.middleware==3.35.0
+oslo.serialization==2.25.0
+oslo.service==1.30.0
+oslo.utils==3.36.0
+oslosphinx==4.18.0
+oslotest==3.3.0
+Paste==2.0.3
+PasteDeploy==1.5.2
+pbr==3.1.1
+pep8==1.5.7
+pika==0.10.0
+pika-pool==0.1.3
+prettytable==0.7.2
+pycadf==2.7.0
+pyflakes==0.8.1
+Pygments==2.2.0
+pyinotify==0.9.6
+pyparsing==2.2.0
+python-dateutil==2.7.0
+python-editor==1.0.3
+python-keystoneclient==3.15.0
+python-magic==0.4.15
+python-mimeparse==1.6.0
+python-subunit==1.2.0
+python-swiftclient==3.5.0
+pytz==2018.3
+PyYAML==3.12
+reno==2.7.0
+repoze.lru==0.7
+requests==2.18.4
+requestsexceptions==1.4.0
+rfc3986==1.1.0
+Routes==2.4.1
+six==1.11.0
+snowballstemmer==1.2.1
+Sphinx==1.6.5
+sphinxcontrib-websupport==1.0.1
+SQLAlchemy==1.2.5
+statsd==3.2.2
+stevedore==1.28.0
+tenacity==4.9.0
+testrepository==0.0.20
+testscenarios==0.5.0
+testtools==2.3.0
+traceback2==1.4.0
+unittest2==1.1.0
+urllib3==1.22
+vine==1.1.4
+WebOb==1.7.4
+Werkzeug==0.14.1
+wrapt==1.10.11

tox.ini

@@ -35,3 +35,10 @@ enable-extensions = H106,H203
 ignore = E123,E125
 builtins = _
 exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build
+
+[testenv:lower-constraints]
+basepython = python3
+deps =
+  -c{toxinidir}/lower-constraints.txt
+  -r{toxinidir}/test-requirements.txt
+  -r{toxinidir}/requirements.txt