Submariner connects multiple Kubernetes clusters in a way that is secure and performant. Submariner flattens the networks between the connected clusters, and enables IP reachability between Pods and Services. Submariner also provides, via Lighthouse, service discovery capabilities. The service discovery model is built using the proposed Kubernetes Multi Cluster Services.
Submariner consists of several main components that work in conjunction to securely connect workloads across multiple Kubernetes clusters, both on-premises and on public clouds:
Submariner has optional components that provide additional functionality:
The diagram below illustrates the basic architecture of Submariner:
ClusterSet - a group of two or more clusters with a high degree of mutual trust that share Services amongst themselves.
Within a cluster set, all namespaces with a given name are considered to be the same namespace.
ServiceExport (CRD) - used to specify which Services should be exposed across all clusters in the cluster set. If multiple clusters
export a Service with the same name and from the same namespace, they will be recognized as a single logical Service.
ServiceExports must be explicitly created by the user in each cluster and within the namespace in which the underlying Service resides,
in order to signify that the Service should be visible and discoverable to other clusters in the cluster set. The
ServiceExport object can
be created manually or via the
subctl export command.
When a Service is exported, it then becomes accessible as
ServiceImport (CRD) - representation of a multi-cluster Service in each cluster. Created and used internally by Lighthouse and does not
require any user action.