Adding a Node

Growing OpenStack capacity is intentionally simple. Because almost everything is described as code and reconciled by FluxCD, you do not edit the Argus repository to add capacity. You join a new node to the openstack Kubernetes cluster and apply the right node labels — the Yaook operators do the rest.

How it works

Yaook operators schedule OpenStack agents onto Kubernetes nodes using nodeSelectors. When a node carries labels that an operator's selector matches, the operator automatically:

schedules the corresponding OpenStack agents onto it (nova-compute, the OVN ovn-controller),
registers it as a hypervisor in Nova, and
wires it into the OVN data plane.

No re-provisioning of the control plane is required — capacity scales by labelling nodes.

Steps

1. Join the node to the Kubernetes cluster

Provision the host with NixOS (see Operating System) and join it to the cluster. For a worker join on the baremetal OpenStack cluster, follow the same kubeadm flow used for the control plane nodes — see Kubernetes Bootstrap.

Verify it appears:

bash

kubectl get nodes

2. Apply the node labels

Label the node so the Yaook operators select it. This includes the Yaook management labels (e.g. node.yaook.cloud/...) plus any labels the operator nodeSelectors match:

bash

kubectl label node <node-name> <label-key>=<label-value>

Where the selectors live

The relevant operator CRs in Argus select nodes via nodeSelectors[].matchLabels:

Nova compute — infrastructure/yaook/nova.yaml:

yaml

compute:
  configTemplates:
    - nodeSelectors:
        - matchLabels: {}

OVN controller — infrastructure/yaook/neutron.yaml:

yaml

setup:
  ovn:
    controller:
      configTemplates:
        - nodeSelectors:
            - matchLabels: {}

match-all default

With the current matchLabels: {} (match-all), these target every node in the cluster — so a freshly joined node is picked up automatically once it has the Yaook management labels. To gate compute/OVN onto specific nodes, set explicit labels in these CRs and apply the matching labels to the node.

Adding a Node ​

How it works ​

Steps ​

1. Join the node to the Kubernetes cluster ​

2. Apply the node labels ​

Where the selectors live ​

See also ​