so the hypervisor create the vnic inside instance and then the nutron will connect this vnic to a specific network through a port.right? heat will read the content of yaml and will decide on which compute the instance will be lauched.right? then those instances are monitored and in log will be

written things like when instance was created of the instance failed to create.

Almost correct. A port is the Neutron abstraction of a network onnection. How the instance is connected depends mostly on Neutron’s core plugin; in case of the ML2 plugin, it then depends on the mechanism driver. For example, via a Linuxbridge plugged into an Openvswitch bridge.

Heat doesn’t decide on which compute node the instance will run. This decision is made by the Nova scheduler. I am not sure to which extent it monitors instances. You can also use the commands openstack stack event list and resource list to see which instance launches were successful.

last thing. if the instance crash or fail then i must look into the logs on that compute server not in controller.right?

heat will use api call to nova to create the instance-then nova will talk to neutron to cinder to glance to attach the network the volume and image to the instance.right?