So i've read several articles & looked through Openstack docs for the definition of a node.
Node
A Node is a logical object managed by the Senlin service. A node can be a member of at most one cluster at any time. A node can be an orphan node which means it doesn’t belong to any clusters.
Node types
According to the Oracle docs, there are different node types (controller node, compute node etc.). What I'm confused about is if a single node is a single physical computer host. Does that mean I can still deploy multiple nodes with different node types on the same host?
Node Cluster
I read that a cluster is a group of nodes. How could the cluster for the controller node look like?
CONTROLLER NODE The controller node is the control plane for the OpenStack environment. The control pane handles identity (keystone), dashboard (Horizon), telemetry (ceilometer), orchestration (heat) and network server service (neutron).
In this architecture, I have different Openstack services (Horizon, Glance etc.) running on one node. Can I conclude from this picture whether it's part of a cluster?
Ok, so a node in the context of the Openstack documentation is synonymous to host:
The example architecture requires at least two nodes (hosts)
from the sentence on the page: https://docs.openstack.org/newton/install-guide-ubuntu/overview.html
You already found out that what a node is in the context of Senlin.
Node types: the nodes referred here are the physical hosts, like in the rest of the Openstack documentation. The node type is determined by the services running on the host. Usually you can run serveral services on a host.
In Openstack the word cluster is only used to referred to service collection managed by Senlin. So usually no, these services need not form a cluster.
