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: Id52de99217d1187e3a1a638c41aba18258b6c824
Depends-On: https://review.openstack.org/555034
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/.zuul.yaml b/.zuul.yaml
index 80554703..47cb6766 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -142,3 +142,7 @@
       jobs:
         - neutron-tempest-plugin-designate-scenario:
             voting: false
+        - openstack-tox-lower-constraints
+    gate:
+      jobs:
+        - openstack-tox-lower-constraints