Before we start troubleshooting problems with the HEAT orchestration service, it's always a good idea to check if the required services are running:

# ps -aux | grep heat

If any of the preceding services are not running, commands related to HEAT will fail.  

For example, if the the heat-api service is not running, you can start it by invoking the following command:

# service heat-api start

If the previous command doesn't start the service, you can manually start the service to figure out the error message that prevents the service from starting:

# sudo -u heat heat-api --config-file=/etc/heat/heat.conf

This command will display startup messages on the console and will also include any error messages. These messages usually provide a hint about the root cause of the problem.

Once the heat-api service is up and running, you can test it by invoking any heat command:

# heat stack-list

The preceding command should list the available stacks or return empty if none are present. If this command returns a time-out error, it indicates that the problem is with the heat-engine service.

To troubleshoot this further, you must look at the heat logs located in /var/log/heat/heat.log on the node that is hosting the HEAT services. In case the default log directory is changed, you can find the location of the log directory in the /etc/heat/heat.conf file for the log_dir parameter. The error messages in the log file should provide hints about the root cause of the problem.

You can attempt to start the heat-engine service by invoking the following command:

# service heat-engine start

If the preceding command fails, you can manually invoke the heat-engine command and check the output of the command:

# sudo -u heat heat-engine --config-file=/etc/heat/heat.conf

Once, you fix the root cause, you can check if the service has started successfully by invoking the following:

# heat service-list command