Thank you schmandforke. The issue was fixed. It was coming because public IP of Openstack was localhost . That's why ManageIQ was not able to discover the Openstack .
I added it as CloudManager and was able to discover it, but while adding it as InfraManager, it says that it requires ironic module at least to discover the same . I am using devstack right now. Is there any workaround or I really do need ironic module?