If you have ever run, or worked in an IT operations environment, you will agree when I say that one of the key aspects of running operations is monitoring and being proactive rather than being reactive.
However, in the hybrid cloud world, this monitoring becomes of paramount importance. The reason for it is we start treating the infrastructure as cattle and most of the time, we don't even try and troubleshoot for the issue, but rather rip and replace the infrastructure. Some of this is actually automatic. For instance, if a Kubernetes pod hosting an application goes down due to the underlying infrastructure, the system will simply spawn a new one in its place and all of this monitoring is essential.
Since you are reading this book, I think it is safe to assume that you are either planning or implementing the creation/optimization or operation of a hybrid cloud environment. In that respect, you will appreciate that in order to go to self-healing applications...