Remove redundant call to get/create default security group

In the instance_create DB API method, it ensures the (legacy) default
security group gets created for the specified project_id if it does
not already exist. If the security group does not exist, it is created
in a separate transaction.

Later in the instance_create method, it reads the default security group
back that it wrote earlier (via the same ensure default security group
code). But since it was written in a separate transaction, the current
transaction will not be able to see it and will get back 0 rows. So, it
creates a duplicate default security group record if project_id=NULL
(which it will be, if running nova-manage db online_data_migrations,
which uses an anonymous RequestContext with project_id=NULL). This
succeeds despite the unique constraint on project_id because in MySQL,
unique constraints are only enforced on non-NULL values [1].

To avoid creation of a duplicate default security group for
project_id=NULL, we can use the default security group object that was
returned from the first security_group_ensure_default call earlier in
instance_create method and remove the second, redundant call.

This also breaks out the security groups setup code from a nested
method as it was causing confusion during code review and is not being
used for any particular purpose. Inspection of the original commit
where it was added in 2012 [2] did not contain any comments about the
nested method and it appeared to either be a way to organize the code
or a way to reuse the 'models' module name as a local variable name.

Closes-Bug: #1824435

[1] https://dev.mysql.com/doc/refman/8.0/en/create-index.html#create-index-unique
[2] https://review.opendev.org/#/c/8973/2/nova/db/sqlalchemy/api.py@1339

Change-Id: Idb205ab5b16bbf96965418cd544016fa9cc92de9

1 files changed, 1 insertions, 6 deletions

diff --git a/gate/post_test_hook.sh b/gate/post_test_hook.sh
index cf2645574c..28ad9b939e 100755
--- a/gate/post_test_hook.sh
+++ b/gate/post_test_hook.sh
@@ -266,13 +266,8 @@ $MANAGE db online_data_migrations
 # creation of a new deleted marker instance.
 set +e
 archive_deleted_rows
+set -e
 
 # Verify whether online data migrations run after archiving will succeed.
 # See for more details: https://bugs.launchpad.net/nova/+bug/1824435
 $MANAGE db online_data_migrations
-rc=$?
-set -e
-if [[ $rc -ne 2 ]]; then
-    echo "Expected return code 2 from online_data_migrations until bug 1824435 is fixed"
-    exit 2
-fi