Bug 1480273

This sounds like there already exists a default subnet. The test has a protection against this and in case the subnet is present, test is skipped (like it's done in upstream gate).

The test is racy, as default subnet can exist only once in cloud and there are two tests that create default and one that updates to default, it happens that tests are running in parallel while the check for existing subnet is at the class level. So it happens that:

 1) class checks for default subnet, it's not there
 3) test1 creates default subnet -> it's fine, we now have our unique resource
 4) test2 creates default subnet -> the error we see cause test1 has the default

From the tempest logs:

Step1:
2017-08-10 07:03:12.341 3008 INFO tempest.lib.common.rest_client [req-07271c2f-6725-4f77-b676-a55a95adbf7b ] Request (DefaultSubnetPoolsTest:setUpClass): 200 GET http://10.0.0.103:9696/v2.0/subnetpools 0.418s
ion/json', 'X-Auth-Token': '<omitted>'}
        Body: None
    Response - Headers: {'status': '200', u'content-length': '18', 'content-location': 'http://10.0.0.103:9696/v2.0/subnetpools', u'date': 'Thu, 10 Aug 2017 11:03:12 GMT', u'content-type': 'application/json', u'connection': 'close', u'x-openstack-request-id': 'req-07271c2f-6725-4f77-b676-a55a95adbf7b'}
        Body: {"subnetpools":[]} _log_request_full /usr/lib/python2.7/site-packages/tempest/lib/common/rest_client.py:425

Step2:
2017-08-10 07:03:12.998 3008 INFO tempest.lib.common.rest_client [req-6322524f-d1d8-4c7c-abd4-f08862bcec60 ] Request (DefaultSubnetPoolsTest:test_admin_create_default_subnetpool): 201 POST http://10.0.0.103:9696/v2.0/subnetpools 0.655s
2017-08-10 07:03:12.998 3008 DEBUG tempest.lib.common.rest_client [req-6322524f-d1d8-4c7c-abd4-f08862bcec60 ] Request - Headers: {'Content-Type': 'application/json', 'Accept': 'application/json', 'X-Auth-Token': '<omitted>'}
        Body: {"subnetpool": {"is_default": true, "prefixes": ["10.11.12.0/24"], "name": "tempest-smoke-subnetpool-2026337716", "min_prefixlen": "29"}}
    Response - Headers: {'status': '201', u'content-length': '508', 'content-location': 'http://10.0.0.103:9696/v2.0/subnetpools', u'date': 'Thu, 10 Aug 2017 11:03:12 GMT', u'content-type': 'application/json', u'connection': 'close', u'x-openstack-request-id': 'req-6322524f-d1d8-4c7c-abd4-f08862bcec60'}
        Body: {"subnetpool":{"is_default":true,"description":"","default_quota":null,"tenant_id":"542c5acbca3f49a0bc89d0903eb5c7e5","created_at":"2017-08-10T11:03:12Z","tags":[],"updated_at":"2017-08-10T11:03:12Z","prefixes":["10.11.12.0/24"],"min_prefixlen":"29","max_prefixlen":"32","address_scope_id":null,"revision_number":0,"ip_version":4,"shared":false,"default_prefixlen":"29","project_id":"542c5acbca3f49a0bc89d0903eb5c7e5","id":"dd1b15f4-0dc1-4582-9435-394a5b2bdea9","name":"tempest-smoke-subnetpool-2026337716"}} _log_request_full /usr/lib/python2.7/site-packages/tempest/lib/common/rest_client.py:425

Step3:
2017-08-10 07:03:15.667 3008 INFO tempest.lib.common.rest_client [req-24e48bfe-473f-44e0-aaf4-8f2debf81a0e ] Request (DefaultSubnetPoolsTest:test_convert_subnetpool_to_default_subnetpool): 400 PUT http://10.0.0.103:9696/v2.0/subnetpools/fb199e24-a9e2-443f-81cc-3c07c3bd7a20 0.842s
2017-08-10 07:03:15.668 3008 DEBUG tempest.lib.common.rest_client [req-24e48bfe-473f-44e0-aaf4-8f2debf81a0e ] Request - Headers: {'Content-Type': 'application/json', 'Accept': 'application/json', 'X-Auth-Token': '<omitted>'}
        Body: {"subnetpool": {"is_default": true}}
    Response - Headers: {'status': '400', u'content-length': '203', 'content-location': 'http://10.0.0.103:9696/v2.0/subnetpools/fb199e24-a9e2-443f-81cc-3c07c3bd7a20', u'date': 'Thu, 10 Aug 2017 11:03:15 GMT', u'content-type': 'application/json', u'connection': 'close', u'x-openstack-request-id': 'req-24e48bfe-473f-44e0-aaf4-8f2debf81a0e'}
        Body: {"NeutronError": {"message": "Invalid input for operation: A default subnetpool for this IP family has already been set. Only one default may exist per IP family.", "type": "InvalidInput", "detail": ""}} _log_request_full /usr/lib/python2.7/site-packages/tempest/lib/common/rest_client.py:425

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHEA-2017:3462