MachineDeployments

Clients

You can manage as the MachineDeployments in your cluster with different clients.

Terraform

resource "metakube_node_deployment" "nodes" {
  cluster_id = metakube_cluster.cluster.id
  spec {
    replicas = var.node_replicas
    template {
      cloud {
        openstack {
          flavor                       = ""
          image                        = data.openstack_images_image_v2.image.name
          use_floating_ip              = false
        }
      }
      operating_system {
        ubuntu {}
      }
      versions {
        kubelet = metakube_cluster.cluster.version
      }
    }
  }
}

Complete examples can be found here.

UI

Our tutorial shows how to manage MachineDeployment in the MetaKube UI.

Kubectl

A manifest for a MachineDeployment could look like this:

apiVersion: cluster.k8s.io/v1alpha1
kind: MachineDeployment
metadata:
  name: nodes
  namespace: kube-system
spec:
  replicas: 2
  selector:
    matchLabels:
      group: nodes
  template:
    metadata:
      labels:
        group: nodes
    spec:
      versions:
        kubelet: 1.30.3
      providerSpec:
        value:
          cloudProvider: openstack
          cloudProviderSpec:
            availabilityZone: dbl1
            flavor: m1.small
            floatingIpPool: ext-net
            image: Ubuntu Noble 24.04 (2024-08-01)
            network: metakube-mmxfcmgjkx
            region: dbl
            securityGroups:
              - metakube-mmxfcmgjkx
            serverGroupID: fe9dcd44-f08a-492a-9e64-4e38e1d51573
            subnet: 2969ae04-a429-4c1b-83e3-2f76fc3a342a
          operatingSystem: ubuntu
          operatingSystemSpec: {}

Node lifecycle

Cluster API

MetaKube models the lifecycle of Nodes with the Kubernetes Cluster API which defines custom resources that are MachineDeployment, MachineSet & Machine.

Provisioning

When a new Machine is created (e.g. during rolling update), MetaKube will:

1. Create OpenStack resources (port, server, floating IP)
2. Wait until Node comes up and becomes Ready
   1. Server boots and gets initialization config from the OpenStack metadata service
   2. Server runs initialization code and installs Kubelet
   3. Kubelet gets a client certificate through the CSR
   4. Kubelet registers the Node for the first time
   5. OpenStack cloud controller manager initializes the Node metadata (e.g. addresses)
   6. Critical DaemonSet Pods (CNI) start running
   7. MetaKube removes the node.syseleven.de/not-ready:NoSchedule taint and marks the Node as Ready

Deletion

MetaKube may delete Machines as part of:

• Rolling updates
• Scaling down of MachineDeployments
• Deletion of MachineDeployments

To safely deprovision a Kubernetes Node, MetaKube will:

1. Mark Machine object for deletion
2. Start draining the Node, honoring potential PodDisruptionBudgets
3. Clean up resources in cloud
4. Delete the Machine object

This makes it safe to delete a Machine (kubectl -n kube-system delete machine my-node-1234) in order to gracefully replace a particular Kubernetes Node.

Rolling Update

Any change to a MachineDeployment's machine template will trigger a rolling update of the nodes.

MetaKube will gradually scale up the new MachineSet and wait until the Nodes join the cluster and become Ready before scaling down the old MachineSet.

Configuration

MachineDeployment

MachineTemplate

CloudProviderSpec (OpenStack)

OperatingSystemSpec (Ubuntu)