Heat is one of the widest-reaching components within the OpenStack infrastructure to troubleshoot. This is because each template that is built is different and has different dependencies among resources created in the stack that is launched. Further, it is able to depend on or create almost any resource within OpenStack. As with the other components, the best starting place is with the Heat logs in /var/log/heat. This will give you a good indication of where things might not be going correctly.

If a stack is launched and does not successfully complete, but you do not see any errors in the Heat logs, then the issue may be in the instances. Heat has callbacks from the running instances that must work for the orchestration of data and the ordering of instance creation within a stack.

If you review the section in this chapter on the metadata server, you will notice that the post-boot configuration that is run on an instance is delivered by the metadata service...