-: So now that we had to look at the worker node,
let's have another look at the master node.
What's the master node doing?
And which software is running in the master node?
Well inside of the master node
the most important thing, the most important service,
the most important software you could say,
which is up and running, is the API server.
This is a simple service, which is running
on the master node machine, which is the counterpoint
for the kubelet services running on the worker nodes.
So this is the counterpart
for the communication between worker and master node.
In addition to this API server,
another service, which is installed and running
on the master node machine, is a so-called scheduler,
which basically is responsible
for watching our pods and choosing worker nodes
on which new pods should be created on,
in case a new pod needs to be added
because a pod got unhealthy and went down,
or because of scaling, we needed to create a new pod.
So this is responsible for actually then telling
the API server what to tell the worker nodes.
And we've got another service,
which is to kube-controller manager,
which in the end watches and controls
the worker nodes overall,
and which is responsible for ensuring
that we get the correct number of pods up and running.
And therefore, it of course works closely together
with the scheduler and the API server.
And there is a specific version of that
kube-controller manager,
which is the cloud-controller manager,
which is doing the same thing,
but which is cloud-provider specific.
And which actually then knows how
to tell that cloud provider,
for example AWS or Microsoft Azure, what to do.
So this cloud-controller manager
basically just translates instructions
to AWS or Azure or whatever you're using.
The big cloud providers, which you are very likely to use
in reality anyways, already got services
which take all that away from you
and where you therefore just needs to provide your
kubernetes configuration and they do all the heavy lifting.
And that's basically it, that's the big picture
and the core architecture.
And as I said,
I'm aware that at this point you will probably still have
a couple of questions related to that,
but that will all become clearer over the next lectures
and modules as we get our hands dirty.