Whenever we hard delete any Project without releasing its resources allocated to that project, then the resources mapped to the unknown (Non-exist) tenant will turn as Orphaned resources.
For example, Deleting the project without deleting the VMs / Networks / Routers / Floating IPs will make those resources allocated to non-existing project. Those resources will stay in our cloud environment forever and occupying the resources space as well.
This script will list the resources that are allocated to non-existing Project IDs.
$ git clone https://github.com/vinothkumarselvaraj/openstack-orphaned-resource.git
$ cd openstack-orphaned-resource
$ python openstack_orphaned_resource.py <--object-->
where object is one or more of “networks’, ‘routers’, ‘subnets’, ‘floatingips’, ‘ports’, ‘servers’, ‘secgroup’ or ‘all'”