Single-Node Clusters on vSphere

Tanzu Kubernetes Grid (TKG) supports single-node clusters. Single-node clusters are workload clusters on which hosted workloads run alongside control plane infrastructure on a single ESXi host.

To further minimize the footprint of a single-node cluster, you can create it from a tiny Tanzu Kubernetes release (TKr), which has a Photon or Ubuntu Tiny OVA for its base OS. Such clusters are called minimal single-node clusters.

Single-node clusters are class-based workload clusters that run on vSphere and are deployed by standalone management clusters.

Single-node clusters are fully supported for Telco Cloud Automation (TCA).

Note
You cannot use Tanzu Mission Control (TMC) to create and manage single-node clusters, but this capability is planned for a future release of TMC.

Single-node cluster use cases include:

Minimal single-node clusters
- Resource-constrained host environments such as far edge cell sites and other edge locations
Standard single-node clusters
- Experimental development and test environments

Compatibility

Single-node clusters are supported for the following environments and components:

Category	Supported Options
Infrastructure	vSphere 7, vSphere 8
Node OS	Ubuntu 22.04, Photon 5 (Kubernetes v1.27 and v1.28); Ubuntu 20.04, Photon 3 (Kubernetes v1.27 and earlier)
Node size	small
Package	Cert Manager, Fluent Bit, Multus, Prometheus, Whereabouts
Control plane endpoint provider	Kube-Vip^*
Workload load balancer	Kube-Vip^*
Workload cluster type	Class-based
CNI	Antrea, Calico
Connectivity mode	Online, Internet-restricted

^*NSX Advanced Load Balancer (ALB) is not supported with single-node clusters in TKG v2.5.

Prerequisites

A vSphere account
A TKG standalone management cluster running TKG v2.5.x on vSphere
A bootstrap machine with the following installed, as described in Install the Tanzu CLI and Kubernetes CLI for Use with Standalone Management Clusters:
- Tanzu CLI
- kubectl

Create a Minimal Single-Node Cluster

To create a single-node workload cluster on vSphere that uses a tiny Tanzu Kubernetes release (TKr) to minimize its footprint:

Prepare the OVA:
1. Go to the Broadcom Support Portal and log in with your VMware customer credentials.
2. Go to the Tanzu Kubernetes Grid downloads page and select 2.5.2.
3. Download the Tiny OVA to use for your single-node cluster:
  - Photon v5 Kubernetes v1.28.11 Tiny OVA
  - Ubuntu 2204 Kubernetes v1.28.11 Tiny OVA
4. Import the Tiny OVA into your vSphere environment and convert it into a VM template as described in Import the Base Image Template into vSphere.

Create the single-node workload cluster.

Note
To create minimal single-node clusters, you must run the tanzu cluster create command with a Kubernetes-style object spec. If you start with a flat cluster configuration file, you must follow a two-step process described in Create a Class-Based Cluster to generate the object spec, and then edit it as described below before running tanzu cluster create a second time to create the cluster.

Set environment variables as set in this example:

export CLUSTER_NAME='workload-snc'
export CLUSTER_NAMESPACE='default'
export CLUSTER_CIDR='100.96.0.0/11'
export SERVICE_CIDR='100.64.0.0/13'
export VSPHERE_CONTROL_PLANE_ENDPOINT=10.185.11.134
export VSPHERE_SERVER=10.185.12.154
export VSPHERE_USERNAME='administrator@vsphere.local'
export VSPHERE_PASSWORD=<encoded:QWRtaW4hMjM=>
export VSPHERE_DATACENTER='/dc0'
export VSPHERE_DATASTORE='/dc0/datastore/sharedVmfs-0'
export VSPHERE_FOLDER='/dc0/vm'
export VSPHERE_NETWORK='/dc0/network/VM Network'
export VSPHERE_RESOURCE_POOL='/dc0/host/cluster0/Resources'
export VSPHERE_SSH_AUTHORIZED_KEY=ssh-rsa AAAAB3[...]tyaw== user@example.com
export VSPHERE_TLS_THUMBPRINT=47:F5:83:8E:5D:36:[...]:72:5A:89:7D:29:E5:DA
export VSPHERE_CONTROL_PLANE_NUM_CPUS='2'
export VSPHERE_CONTROL_PLANE_MEM_MIB='4096'
export VSPHERE_CONTROL_PLANE_DISK_GIB='20'
export TKG_CUSTOM_IMAGE_REPOSITORY='projects.registry.vmware.com/tkg'
export OS_NAME='photon'
export TKG_CUSTOM_IMAGE_REPOSITORY_CA_CERTIFICATE="LS0tL[...]0tLQo="

Create a manifest vsphere-snc.yaml with Cluster and Secret object specs referencing the above variables:

apiVersion: cluster.x-k8s.io/v1beta1
kind: Cluster
metadata:
  annotations:
    tkg.tanzu.vmware.com/cluster-controlplane-endpoint: ${VSPHERE_CONTROL_PLANE_ENDPOINT}
    run.tanzu.vmware.com/resolve-tkr: 'tkr.tanzu.vmware.com/tiny'
  labels:
    tkg.tanzu.vmware.com/cluster-name: ${CLUSTER_NAME}
  name: ${CLUSTER_NAME}
  namespace: ${CLUSTER_NAMESPACE}
spec:
  clusterNetwork:
    pods:
      cidrBlocks:
      - ${CLUSTER_CIDR}
    services:
      cidrBlocks:
      - ${SERVICE_CIDR}
  topology:
    class: tkg-vsphere-default-v1.1.1
    controlPlane:
      metadata:
        annotations:
          run.tanzu.vmware.com/resolve-os-image: image-type=ova,os-name=${OS_NAME}
      replicas: 1
    variables:
    - name: controlPlaneTaint
      value: false
    - name: auditLogging
      value:
        enabled: false
    - name: apiServerEndpoint
      value: ${VSPHERE_CONTROL_PLANE_ENDPOINT}
    - name: aviAPIServerHAProvider
      value: false
    - name: imageRepository
      value:
        host: ${TKG_CUSTOM_IMAGE_REPOSITORY}
    - name: trust
      value:
        additionalTrustedCAs:
        - data: ${TKG_CUSTOM_IMAGE_REPOSITORY_CA_CERTIFICATE}
          name: imageRepository
    - name: vcenter
      value:
        cloneMode: fullClone
        datacenter: ${VSPHERE_DATACENTER}
        datastore: ${VSPHERE_DATASTORE}
        folder: ${VSPHERE_FOLDER}
        network: ${VSPHERE_NETWORK}
        resourcePool: ${VSPHERE_RESOURCE_POOL}
        server: ${VSPHERE_SERVER}
        storagePolicyID: ""
        tlsThumbprint: ${VSPHERE_TLS_THUMBPRINT}
    - name: user
      value:
        sshAuthorizedKeys:
        - ${VSPHERE_SSH_AUTHORIZED_KEY}
    - name: controlPlane
      value:
        machine:
          diskGiB: ${VSPHERE_CONTROL_PLANE_DISK_GIB}
          memoryMiB: ${VSPHERE_CONTROL_PLANE_MEM_MIB}
          numCPUs: ${VSPHERE_CONTROL_PLANE_NUM_CPUS}
    version: v1.28.11+vmware.1-tiny.2
---
apiVersion: v1
kind: Secret
metadata:
  name: ${CLUSTER_NAME}
  namespace: ${CLUSTER_NAMESPACE}
stringData:
  password: ${VSPHERE_PASSWORD}
  username: ${VSPHERE_USERNAME}
EOF

Note the following:

The metadata.annotations setting for run.tanzu.vmware.com/resolve-tkr
The topology.variables setting for controlPlaneTaint
There is no topology.workers block, only topology.controlPlane
For prior versions of TKG, the topology.version should be:
- v2.5.0: v1.28.4+vmware.1-tiny.1
- v2.4.1: v1.27.5+vmware.1-tiny.1
- v2.3.1: v1.26.8+vmware.1-tiny.1
- v2.2.0: v1.25.7+vmware.1-tiny.1
- v2.1.1: v1.24.10+vmware.1-tiny.1

(Optional) To configure the cluster to use Calico as the CNI instead of the default Antrea CNI, follow the instructions for single-node clusters in Calico CNI for Single-Node Class-Based Workload Clusters.

Apply the Cluster object manifest:

tanzu cluster create -f vsphere-snc.yaml

Create a Standard Single-Node Cluster

To create a single-node workload cluster on vSphere that uses a standard Photon or Ubuntu TKr:

Create a flat configuration file for the workload cluster as described in vSphere with Standalone Management Cluster Configuration Files.
Run tanzu cluster create with the --dry-run flag to convert the flat configuration file into a Kubernetes-style Cluster object spec as described in Create an Object Spec.
Edit the Cluster object spec to include the following settings:
- Under topology.controlPlane:
```
replicas: 1
```
- No topology.workers block; if present, delete it.
- Under topology.variables:
```
- name: controlPlaneTaint
  value: false
```
- (Optional) to set maximum pod counts, under topology.variables include max-pods settings as extra arguments for the control plane or worker kubelets. For example, to set both control plane and worker pod counts to a maximum of 254:
```
- name: controlPlaneKubeletExtraArgs
  value:
    max-pods: "254"
- name: workerKubeletExtraArgs
  value:
    max-pods: "254"
```
Run tanzu cluster create with the modified Cluster object spec as described in Create a Class-Based Cluster from the Object Spec.