It is very simple to scale-out a TKGm cluster. The command
tanzu cluster scale cluster_name --controlplane-machine-count 5 --worker-machine-count 10will easily do this for you, this is known as horizontal scale-out. But have you thought of how to scale-up control plane or worker nodes with more CPU or memory?
This post discusses how you can scale up a TKGm worker node, tl;dr how to increase or decrease worker node CPU, RAM, disk.
Getting started
It is not a simple process to scale-up as it is to scale-out. Follow the steps below to scale-up your TKGm cluster.
Step 1.
Run the following command to obtain the list of vSphere machine templates that TKGm uses to deploy control plane and worker nodes.
kubectl get vspheremachinetemplate
NAME AGE
tkg-ssc-control-plane 3d1h
tkg-ssc-worker 3d1h
tkg-workload-01-control-plane 3d
tkg-workload-01-worker 3d
You can see that there are four machine templates.
Lets say we want to increase the size of the worker nodes in the tkg-workload-01 cluster.
Lets describe the tkg-workload-01-worker machine template.
kubectl describe vspheremachinetemplate tkg-workload-01-worker
Name: tkg-workload-01-worker
Namespace: default
Labels: <none>
Annotations: <none>
API Version: infrastructure.cluster.x-k8s.io/v1alpha3
Kind: VSphereMachineTemplate
Metadata:
Creation Timestamp: 2021-10-29T14:11:25Z
Generation: 1
Managed Fields:
API Version: infrastructure.cluster.x-k8s.io/v1alpha3
Fields Type: FieldsV1
fieldsV1:
f:metadata:
f:annotations:
.:
f:kubectl.kubernetes.io/last-applied-configuration:
f:spec:
.:
f:template:
.:
f:spec:
.:
f:cloneMode:
f:datacenter:
f:datastore:
f:diskGiB:
f:folder:
f:memoryMiB:
f:network:
.:
f:devices:
f:numCPUs:
f:resourcePool:
f:server:
f:storagePolicyName:
f:template:
Manager: kubectl-client-side-apply
Operation: Update
Time: 2021-10-29T14:11:25Z
API Version: infrastructure.cluster.x-k8s.io/v1alpha3
Fields Type: FieldsV1
fieldsV1:
f:metadata:
f:ownerReferences:
.:
k:{"uid":"be507594-0c05-4d30-8ed6-56811733df23"}:
.:
f:apiVersion:
f:kind:
f:name:
f:uid:
Manager: manager
Operation: Update
Time: 2021-10-29T14:11:25Z
Owner References:
API Version: cluster.x-k8s.io/v1alpha3
Kind: Cluster
Name: tkg-workload-01
UID: be507594-0c05-4d30-8ed6-56811733df23
Resource Version: 45814
UID: fc1f3d9f-078f-4282-b93f-e46593a760a5
Spec:
Template:
Spec:
Clone Mode: fullClone
Datacenter: /TanzuPOC
Datastore: tanzu_ssd_02
Disk Gi B: 40
Folder: /TanzuPOC/vm/tkg-vsphere-workload
Memory Mi B: 16384
Network:
Devices:
dhcp4: true
Network Name: /TanzuPOC/network/TKG-wkld
Num CP Us: 4
Resource Pool: /TanzuPOC/host/Workload Cluster 1/Resources/tkg-vsphere-workload
Server: vcenter.vmwire.com
Storage Policy Name:
Template: /TanzuPOC/vm/ubuntu-2004-kube-v1.21.2+vmware.1
Events: <none>
You can see that this machine template has 16GB of RAM and 4 vCPUs. Lets say we want to increase workers to 120GB of RAM and 24 vCPUs, how would we do this?
Step 2.
We need to clone the currently in use machine template into a new one and then apply it.
kubectl get vspheremachinetemplate tkg-workload-01-worker -o yaml > new-machine-template.yamlStep 3.
Now that we have exported the current machine template into a new yaml file, we can edit it to suit our needs. Edi the file and make the changes to the file.
apiVersion: infrastructure.cluster.x-k8s.io/v1alpha3
kind: VSphereMachineTemplate
metadata:
annotations:
kubectl.kubernetes.io/last-applied-configuration: |
{"apiVersion":"infrastructure.cluster.x-k8s.io/v1alpha3","kind":"VSphereMachineTemplate","metadata":{"annotations":{},"creationTimestamp":"2021-10-29T14:11:25Z","generation":1,"name":"tkg-workload-01-worker-scale","namespace":"default","ownerReferences":[{"apiVersion":"cluster.x-k8s.io/v1alpha3","kind":"Cluster","name":"tkg-workload-01","uid":"be507594-0c05-4d30-8ed6-56811733df23"}],"resourceVersion":"45814","uid":"fc1f3d9f-078f-4282-b93f-e46593a760a5"},"spec":{"template":{"spec":{"cloneMode":"fullClone","datacenter":"/TanzuPOC","datastore":"tanzu_ssd_02","diskGiB":40,"folder":"/TanzuPOC/vm/tkg-vsphere-workload","memoryMiB":122880,"network":{"devices":[{"dhcp4":true,"networkName":"/TanzuPOC/network/TKG-wkld"}]},"numCPUs":24,"resourcePool":"/TanzuPOC/host/Workload Cluster 1/Resources/tkg-vsphere-workload","server":"tanzuvcenter01.ete.ka.sw.ericsson.se","storagePolicyName":"","template":"/TanzuPOC/vm/ubuntu-2004-kube-v1.21.2+vmware.1"}}}}
creationTimestamp: "2021-11-01T11:18:08Z"
generation: 1
name: tkg-workload-01-worker-scale
namespace: default
ownerReferences:
- apiVersion: cluster.x-k8s.io/v1alpha3
kind: Cluster
name: tkg-workload-01
uid: be507594-0c05-4d30-8ed6-56811733df23
resourceVersion: "1590589"
uid: 8697ec4c-7118-4ff0-b4cd-a456cb090f58
spec:
template:
spec:
cloneMode: fullClone
datacenter: /TanzuPOC
datastore: tanzu_ssd_02
diskGiB: 40
folder: /TanzuPOC/vm/tkg-vsphere-workload
memoryMiB: 122880
network:
devices:
- dhcp4: true
networkName: /TanzuPOC/network/TKG-wkld
numCPUs: 24
resourcePool: /TanzuPOC/host/Workload Cluster 1/Resources/tkg-vsphere-workload
server: vcenter.vmwire.com
storagePolicyName: ""
template: /TanzuPOC/vm/ubuntu-2004-kube-v1.21.2+vmware.1
Change lines 6 and 9 by appending a new name to the machine template, you’ll notice that the original name was tkg-workload-01-worker, I appended “scale” to it so the new name of this new machine template is tkg-workload-01-worker-scale.
Step 4.
We can now apply the new machine template with this command
kubectl apply –f new-machine-template.yamlWe can check that the new machine template exists by running this command
kubectl get vspheremachinetemplate
NAME AGE
tkg-ssc-control-plane 3d1h
tkg-ssc-worker 3d1h
tkg-workload-01-control-plane 3d
tkg-workload-01-worker 3d
tkg-workload-01-worker-scale 10s
Step 5.
Now we can apply the new machine template to our cluster.
Before doing that, we need to obtain the machine deployment details for the tkg-workload-01 cluster, we can get this information by running these commands
kubectl get MachineDeployment
NAME PHASE REPLICAS READY UPDATED UNAVAILABLE
tkg-ssc-md-0 Running 3 3 3
tkg-workload-01-md-0 Running 4 4 4
We are interested in the tkg-workload-01-md-0 machine deployment so lets describe it.
kubectl describe MachineDeployment tkg-workload-01-md-0
Name: tkg-workload-01-md-0
Namespace: default
Labels: cluster.x-k8s.io/cluster-name=tkg-workload-01
Annotations: machinedeployment.clusters.x-k8s.io/revision: 3
API Version: cluster.x-k8s.io/v1alpha3
Kind: MachineDeployment
Metadata:
Creation Timestamp: 2021-10-29T14:11:25Z
Generation: 7
Managed Fields:
API Version: cluster.x-k8s.io/v1alpha3
Fields Type: FieldsV1
fieldsV1:
f:metadata:
f:annotations:
.:
f:kubectl.kubernetes.io/last-applied-configuration:
f:labels:
.:
f:cluster.x-k8s.io/cluster-name:
f:spec:
.:
f:clusterName:
f:selector:
.:
f:matchLabels:
.:
f:cluster.x-k8s.io/cluster-name:
f:template:
.:
f:metadata:
.:
f:labels:
.:
f:cluster.x-k8s.io/cluster-name:
f:node-pool:
f:spec:
.:
f:bootstrap:
.:
f:configRef:
.:
f:apiVersion:
f:kind:
f:name:
f:clusterName:
f:infrastructureRef:
.:
f:apiVersion:
f:kind:
f:version:
Manager: kubectl-client-side-apply
Operation: Update
Time: 2021-10-29T14:11:25Z
API Version: cluster.x-k8s.io/v1alpha3
Fields Type: FieldsV1
fieldsV1:
f:spec:
f:template:
f:spec:
f:infrastructureRef:
f:name:
Manager: kubectl-edit
Operation: Update
Time: 2021-11-01T11:25:51Z
API Version: cluster.x-k8s.io/v1alpha3
Fields Type: FieldsV1
fieldsV1:
f:spec:
f:replicas:
Manager: tanzu-plugin-cluster
Operation: Update
Time: 2021-11-01T12:33:35Z
API Version: cluster.x-k8s.io/v1alpha3
Fields Type: FieldsV1
fieldsV1:
f:metadata:
f:annotations:
f:machinedeployment.clusters.x-k8s.io/revision:
f:ownerReferences:
.:
k:{"uid":"be507594-0c05-4d30-8ed6-56811733df23"}:
.:
f:apiVersion:
f:kind:
f:name:
f:uid:
f:status:
.:
f:availableReplicas:
f:observedGeneration:
f:phase:
f:readyReplicas:
f:replicas:
f:selector:
f:updatedReplicas:
Manager: manager
Operation: Update
Time: 2021-11-01T14:30:38Z
Owner References:
API Version: cluster.x-k8s.io/v1alpha3
Kind: Cluster
Name: tkg-workload-01
UID: be507594-0c05-4d30-8ed6-56811733df23
Resource Version: 1665423
UID: 5148e564-cf66-4581-8941-c3024c58967e
Spec:
Cluster Name: tkg-workload-01
Min Ready Seconds: 0
Progress Deadline Seconds: 600
Replicas: 4
Revision History Limit: 1
Selector:
Match Labels:
cluster.x-k8s.io/cluster-name: tkg-workload-01
Strategy:
Rolling Update:
Max Surge: 1
Max Unavailable: 0
Type: RollingUpdate
Template:
Metadata:
Labels:
cluster.x-k8s.io/cluster-name: tkg-workload-01
Node - Pool: tkg-workload-01-worker-pool
Spec:
Bootstrap:
Config Ref:
API Version: bootstrap.cluster.x-k8s.io/v1alpha3
Kind: KubeadmConfigTemplate
Name: tkg-workload-01-md-0
Cluster Name: tkg-workload-01
Infrastructure Ref:
API Version: infrastructure.cluster.x-k8s.io/v1alpha3
Kind: VSphereMachineTemplate
Name: tkg-workload-01-worker
Version: v1.21.2+vmware.1
Status:
Available Replicas: 4
Observed Generation: 7
Phase: Running
Ready Replicas: 4
Replicas: 4
Selector: cluster.x-k8s.io/cluster-name=tkg-workload-01
Updated Replicas: 4
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal SuccessfulScale 90s (x2 over 114m) machinedeployment-controller Scaled down MachineSet "tkg-workload-01-md-0-647645ddcd" to 4
The line that we are interested in is line 38. This is the current machine template that this cluster is using, you’ll notice that it is of course using the original spec, what we need to do is change it to the new spec that we created earlier. If you remember, we named that one tkg-workload-01-worker-scale.
Step 6.
kubectl edit MachineDeployment tkg-workload-01-md-0
# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
apiVersion: cluster.x-k8s.io/v1alpha3
kind: MachineDeployment
metadata:
annotations:
kubectl.kubernetes.io/last-applied-configuration: |
{"apiVersion":"cluster.x-k8s.io/v1alpha3","kind":"MachineDeployment","metadata":{"annotations":{},"labels":{"cluster.x-k8s.io/cluster-name":"tkg-workload-01"},"name":"tkg-workload-01-md-0","namespace":"default"},"spec":{"clusterName":"tkg-workload-01","replicas":4,"selector":{"matchLabels":{"cluster.x-k8s.io/cluster-name":"tkg-workload-01"}},"template":{"metadata":{"labels":{"cluster.x-k8s.io/cluster-name":"tkg-workload-01","node-pool":"tkg-workload-01-worker-pool"}},"spec":{"bootstrap":{"configRef":{"apiVersion":"bootstrap.cluster.x-k8s.io/v1alpha3","kind":"KubeadmConfigTemplate","name":"tkg-workload-01-md-0"}},"clusterName":"tkg-workload-01","infrastructureRef":{"apiVersion":"infrastructure.cluster.x-k8s.io/v1alpha3","kind":"VSphereMachineTemplate","name":"tkg-workload-01-worker"},"version":"v1.21.2+vmware.1"}}}}
machinedeployment.clusters.x-k8s.io/revision: "3"
creationTimestamp: "2021-10-29T14:11:25Z"
generation: 7
labels:
cluster.x-k8s.io/cluster-name: tkg-workload-01
name: tkg-workload-01-md-0
namespace: default
ownerReferences:
- apiVersion: cluster.x-k8s.io/v1alpha3
kind: Cluster
name: tkg-workload-01
uid: be507594-0c05-4d30-8ed6-56811733df23
resourceVersion: "1665423"
uid: 5148e564-cf66-4581-8941-c3024c58967e
spec:
clusterName: tkg-workload-01
minReadySeconds: 0
progressDeadlineSeconds: 600
replicas: 4
revisionHistoryLimit: 1
selector:
matchLabels:
cluster.x-k8s.io/cluster-name: tkg-workload-01
strategy:
rollingUpdate:
maxSurge: 1
maxUnavailable: 0
type: RollingUpdate
template:
metadata:
labels:
cluster.x-k8s.io/cluster-name: tkg-workload-01
node-pool: tkg-workload-01-worker-pool
spec:
bootstrap:
configRef:
apiVersion: bootstrap.cluster.x-k8s.io/v1alpha3
kind: KubeadmConfigTemplate
name: tkg-workload-01-md-0
clusterName: tkg-workload-01
infrastructureRef:
apiVersion: infrastructure.cluster.x-k8s.io/v1alpha3
kind: VSphereMachineTemplate
name: tkg-workload-01-worker-scale
version: v1.21.2+vmware.1
status:
availableReplicas: 4
observedGeneration: 7
phase: Running
readyReplicas: 4
replicas: 4
selector: cluster.x-k8s.io/cluster-name=tkg-workload-01
updatedReplicas: 4
The line that we are interested in is line 54. We need to change the machine template from that old one to our new one.
Lets make that change by going down to line 54 and adding “-scale” to the end of that line. Once you save and quit using “:wq!”. Kubernetes will make do a rolling update of your TKGm cluster for you.
Finishing off
Once the rolling update is done, you can check vSphere Web Client for new VMs being cloned and old ones being deleted. You can also run the command below to see the status of the rolling updates.
kubectl get MachineDeploymentYou’ll then see that your new worker nodes have been resized without interrupting any of the running pods in the cluster.
VMwire 
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