Create subnets

After creating the MetalLB configuration as described in Configure and verify MetalLB and before creating L2 templates, ensure that you have the required subnets that can be used in the L2 template to allocate IP addresses for the MOSK cluster nodes. Where required, create a number of subnets for a particular project using the Subnet CR. A subnet has the following logical scopes:

Each subnet used in an L2 template has its logical scope that is set using the scope parameter in the corresponding L2Template.spec.l3Layout section. One of the following logical scopes is used for each subnet referenced in an L2 template:

  • global - CR uses the default namespace. A subnet can be used for any cluster located in any project.

  • namespaced - CR uses the namespace that corresponds to a particular project where MOSK clusters are located. A subnet can be used for any cluster located in the same project.

  • cluster - Unsupported since Container Cloud 2.28.0 (Cluster releases 17.3.0 and 16.3.0). CR uses the namespace where the referenced cluster is located. A subnet is only accessible to the cluster that L2Template.metadata.labels:cluster.sigs.k8s.io/cluster-name (mandatory since MOSK 23.3) or L2Template.spec.clusterRef (deprecated since MOSK 23.3) refers to. The Subnet objects with the cluster scope will be created for every new cluster.

Note

The use of the ipam/SVC-MetalLB label in Subnet objects is unsupported as part of the MetalLBConfigTemplate object deprecation since Container Cloud 2.27.0 (Cluster releases 17.2.0 and 16.2.0). No actions are required for existing objects. A Subnet object containing this label will be ignored by baremetal-provider after cluster update to the mentioned Cluster releases.

You can have subnets with the same name in different projects. In this case, the subnet that has the same project as the cluster will be used. One L2 template may often reference several subnets, those subnets may have different scopes in this case.

The IP address objects (IPaddr CR) that are allocated from subnets always have the same project as their corresponding IpamHost objects, regardless of the subnet scope.

You can create subnets using either the Container Cloud web UI or CLI.