Cluster API in case you don’t know it is:
a Kubernetes sub-project focused on providing declarative APIs and tooling to simplify provisioning, upgrading, and operating multiple Kubernetes clusters.
Multi-tenancy is defined by the project itself:
Starting from v0.6.5, single controller multi-tenancy is supported that allows using a different AWS Identity for each workload cluster. For details, see the multi-tenancy proposal.
That is exactly what we are going to see in this post.