Add more racks to an existing MOSK cluster

This section describes exemplary L2 templates to demonstrate how to add more racks to an existing MOSK cluster.

The following exemplary L2 template belongs to a single-rack MOSK cluster. This template has the following characteristics:

  • Describes all networks that are used for cluster nodes communication

  • Can be transformed into several L2 templates depending on nodes roles

  • Uses the IP gateway in the external network as default route on the nodes in the MOSK cluster

To add nodes to the new rack of the same cluster:

  1. Create Subnet objects for the following networks: LCM, workload, tenant, and Ceph (where applicable).

  2. Create a new L2 template that nodes in a new rack will use.

  3. In this template, configure the external network to be either stretched between racks or connected to the first rack only.

    Caution

    API/LCM network is the first rack LCM network in our example, since a single-rack MOSK cluster was deployed first. Therefore, only the first rack can contain Kubernetes master nodes that provide access to Kubernetes API.

  4. In the L2 template for the first rack, add IP routes pointing to the networks in the new rack.

The following examples contain:

  • The modified L2 template for the first rack. Routes added to the second rack are highlighted.

  • The new L2 template for the second rack with external network that is stretched between racks. The IP gateway in the external network is used as the default route on the nodes of the second rack.