Description of problem: Users are prone to making mistakes in heat templates. Error messages issued when deploying using TripleO are non-obvious. yamllint can/should be used to debug the errors. The troubleshooting section of the Director Install and Config guide can give advice to use yamllint to debug yaml files.
This bug is against a Version which has reached End of Life. If it's still present in supported release (http://releases.openstack.org), please update Version and reopen.