Nodes and Links

Node and Link resources form the primary c9s API. A Node contains one containerlab node definition, while a Link contains one connection between two node interfaces.

Both resources are namespace-scoped. A namespace is therefore the boundary of a directly authored lab, and both endpoints of a Link must refer to Nodes in that namespace.

Node

The Node name is the containerlab node name. Its specification uses containerlab vocabulary for fields such as kind, image, type, startup-config, and exec.

apiVersion: c9s.run/v1alpha1
kind: Node
metadata:
  name: srl1
spec:
  launcherProfileRef:
    name: lab-policy
  kind: nokia_srlinux
  image: ghcr.io/nokia/srlinux:26.3

A Node can reference one same-namespace LauncherProfile. If the reference is omitted, global Config defaults apply. An explicit reference that does not exist prevents the Node from being realized.

Link

A Link declares exactly two endpoints and the connectivity mechanism used to join them.

apiVersion: c9s.run/v1alpha1
kind: Link
metadata:
  name: srl1-e1-1-multitool-eth1
spec:
  endpointA:
    nodeName: srl1
    interfaceName: e1-1
  endpointB:
    nodeName: multitool
    interfaceName: eth1
  connectivity: vxlan

Wiring belongs only to Link objects; interfaces are not embedded into Node specifications. The link controller validates endpoints and records tunnel allocation in status, while each launcher watches only the Links terminating on its Nodes.

Why direct resources?

Each Node grows only with its own configuration and each Link remains one wire. This removes the single aggregate-object size limit of a source Topology and allows tooling such as clabverter --emit-crs to produce independently reconciled resources.

Direct resources do not promise unlimited scale: Kubernetes API capacity, controller throughput, and the total object count still matter.

Complete example

The individual-resource SR Linux and multitool example contains a LauncherProfile, two Nodes, and one Link.

See the Node reference and Link reference for all fields.