This walkthrough will demonstrate a concrete operational session that employs vmss-prototype to freshen the OS configuration on a node pool. This solution scales nicely, and we hope that demonstrating on a 10 node pool is sufficient to suggest the value of being able to more rapidly, reliably freshen large (> 100 nodes) clusters.
Initially, let's take a look at our example cluster:
$ k get nodes -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
k8s-agentpool1-26100436-vmss000000 Ready agent 2m12s v1.20.1 10.240.0.4 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000001 Ready agent 119s v1.20.1 10.240.0.35 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000002 Ready agent 87s v1.20.1 10.240.0.66 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000003 Ready agent 2m11s v1.20.1 10.240.0.97 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000004 Ready agent 2m6s v1.20.1 10.240.0.128 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000005 Ready agent 2m8s v1.20.1 10.240.0.159 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000006 Ready agent 2m7s v1.20.1 10.240.0.190 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000007 Ready agent 118s v1.20.1 10.240.0.221 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000008 Ready agent 2m16s v1.20.1 10.240.0.252 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000009 Ready agent 2m6s v1.20.1 10.240.1.27 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-master-26100436-0 Ready master 2m40s v1.20.1 10.255.255.5 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14By logging onto one of the nodes, I can see that there are several security patches needed:
$ ssh k8s-agentpool1-26100436-vmss000000
Authorized uses only. All activity may be monitored and reported.
Welcome to Ubuntu 18.04.5 LTS (GNU/Linux 5.4.0-1032-azure x86_64)
* Documentation: https://help.ubuntu.com
* Management: https://landscape.canonical.com
* Support: https://ubuntu.com/advantage
System information as of Fri Jan 8 20:36:12 UTC 2021
System load: 0.27 Processes: 160
Usage of /: 32.1% of 28.90GB Users logged in: 0
Memory usage: 7% IP address for eth0: 10.240.0.4
Swap usage: 0% IP address for docker0: 172.17.0.1
50 packages can be updated.
33 updates are security updates.
Last login: Fri Jan 8 20:36:08 2021 from 10.255.255.5
To run a command as administrator (user "root"), use "sudo <command>".
See "man sudo_root" for details.Let's make sure that list is fresh by running apt update:
azureuser@k8s-agentpool1-26100436-vmss000000:~$ sudo apt update
Hit:1 https://packages.microsoft.com/ubuntu/18.04/prod bionic InRelease
Hit:2 https://repo.iovisor.org/apt/bionic bionic InRelease
Get:3 http://security.ubuntu.com/ubuntu bionic-security InRelease [88.7 kB]
Hit:4 http://azure.archive.ubuntu.com/ubuntu bionic InRelease
Hit:5 http://azure.archive.ubuntu.com/ubuntu bionic-updates InRelease
Hit:6 http://azure.archive.ubuntu.com/ubuntu bionic-backports InRelease
Fetched 88.7 kB in 3s (29.5 kB/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
41 packages can be upgraded. Run 'apt list --upgradable' to see them.Now, let's get them all:
azureuser@k8s-agentpool1-26100436-vmss000000:~$ sudo apt-get dist-upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages were automatically installed and are no longer required:
libapr1 libaprutil1 libauparse0 libopts25 linux-headers-4.15.0-124
Use 'sudo apt autoremove' to remove them.
The following NEW packages will be installed:
linux-azure-5.4-cloud-tools-5.4.0-1036 linux-azure-5.4-headers-5.4.0-1036 linux-azure-5.4-tools-5.4.0-1036 linux-cloud-tools-5.4.0-1036-azure linux-headers-5.4.0-1036-azure linux-image-5.4.0-1036-azure
linux-modules-5.4.0-1036-azure linux-modules-extra-5.4.0-1036-azure linux-tools-5.4.0-1036-azure
The following packages will be upgraded:
apport apt apt-transport-https apt-utils blobfuse cloud-init curl libapt-inst2.0 libapt-pkg5.0 libc-bin libc-dev-bin libc6 libc6-dev libcurl3-gnutls libcurl4 libp11-kit0 libsasl2-2 libsasl2-modules
libsasl2-modules-db libssl1.0.0 libssl1.1 linux-azure linux-cloud-tools-azure linux-cloud-tools-common linux-headers-azure linux-image-azure linux-libc-dev linux-tools-azure linux-tools-common locales
multiarch-support openssl python-apt-common python3-apport python3-apt python3-distupgrade python3-problem-report tzdata ubuntu-release-upgrader-core update-notifier-common wireless-regdb
41 upgraded, 9 newly installed, 0 to remove and 0 not upgraded.
Need to get 79.3 MB of archives.
After this operation, 241 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
<...>
<output truncated>
<...>
doneWhile we're here, let's manually invoke unattended-upgrade to get those immediately:
azureuser@k8s-agentpool1-26100436-vmss000000:~$ sudo unattended-upgrade
azureuser@k8s-agentpool1-26100436-vmss000000:~$ echo $?
0At this point, we can confirm that there's nothing else to get:
$ sudo apt list --upgradable
Listing... DoneCompare this to the remaining nodes in the cluster:
$ for i in `seq 1 9`; do ssh k8s-agentpool1-26100436-vmss00000$i "sudo apt list --upgradable | wc -l"; done
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
42
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
18
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
42
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
42
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
42
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
42
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
42
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
18
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
42Logging back onto our updated node in this pool, we can observe that a reboot is required to actually apply all updated patches:
azureuser@k8s-agentpool1-26100436-vmss000000:~$ cat /var/run/reboot-required
*** System restart required ***Now, in order to actually apply these updates on this node, let's cordon + drain it from the cluster...:
$ k cordon k8s-agentpool1-26100436-vmss000000
node/k8s-agentpool1-26100436-vmss000000 cordoned
$ k get node k8s-agentpool1-26100436-vmss000000
NAME STATUS ROLES AGE VERSION
k8s-agentpool1-26100436-vmss000000 Ready,SchedulingDisabled agent 18m v1.20.1
$ k drain --ignore-daemonsets --delete-emptydir-data --force --grace-period 300 --timeout 900s k8s-agentpool1-26100436-vmss000000
node/k8s-agentpool1-26100436-vmss000000 already cordoned
WARNING: ignoring DaemonSet-managed Pods: kube-system/azure-cni-networkmonitor-m8rzb, kube-system/azure-ip-masq-agent-wqkxb, kube-system/blobfuse-flexvol-installer-8d5fz, kube-system/csi-secrets-store-provider-azure-77gbz, kube-system/csi-secrets-store-s5jp9, kube-system/kube-proxy-sck72
node/k8s-agentpool1-26100436-vmss000000 drained
$ echo $?
0And reboot it:
azureuser@k8s-agentpool1-26100436-vmss000000:~$ sudo reboot && exit
Connection to k8s-agentpool1-26100436-vmss000000 closed by remote host.
Connection to k8s-agentpool1-26100436-vmss000000 closed.Verify that the reboot is successful:
$ ssh k8s-agentpool1-26100436-vmss000000
Authorized uses only. All activity may be monitored and reported.
Welcome to Ubuntu 18.04.5 LTS (GNU/Linux 5.4.0-1036-azure x86_64)
* Documentation: https://help.ubuntu.com
* Management: https://landscape.canonical.com
* Support: https://ubuntu.com/advantage
System information as of Fri Jan 8 20:56:16 UTC 2021
System load: 1.58 Processes: 167
Usage of /: 35.2% of 28.90GB Users logged in: 0
Memory usage: 6% IP address for eth0: 10.240.0.4
Swap usage: 0% IP address for docker0: 172.17.0.1
0 packages can be updated.
0 of these updates are security updates.
Last login: Fri Jan 8 20:46:55 2021 from 10.255.255.5
azureuser@k8s-agentpool1-26100436-vmss000000:~$ sudo apt list --upgradable
Listing... Done
azureuser@k8s-agentpool1-26100436-vmss000000:~$ ls -la /var/run/reboot-required
ls: cannot access '/var/run/reboot-required': No such file or directoryNode k8s-agentpool1-26100436-vmss000000 is looking good! Just for fun, let's fingerprint this node as another mark of what can be done using vmss-prototype:
azureuser@k8s-agentpool1-26100436-vmss000000:~$ ls -la /var/log/vmss-prototype-was-here
ls: cannot access '/var/log/vmss-prototype-was-here': No such file or directory
azureuser@k8s-agentpool1-26100436-vmss000000:~$ sudo touch /var/log/vmss-prototype-was-hereWe can now return the node to service, so that we can use it as the target node in a vmss-prototype run (vmss-prototype requires a Ready node as part of its initial validation that a node VM is an appropriate candidate for taking a snapshot and propagating to the VMSS model):
$ k uncordon k8s-agentpool1-26100436-vmss000000
node/k8s-agentpool1-26100436-vmss000000 uncordoned
FrancisBookMS:aks-engine jackfrancis$ k get node k8s-agentpool1-26100436-vmss000000
NAME STATUS ROLES AGE VERSION
k8s-agentpool1-26100436-vmss000000 Ready agent 29m v1.20.1It is at this point that you would want to operationally validate this node. Perhaps run replicas of your production workloads on it using an appropriate nodeSelector, to confidently conclude that the changed node is indeed running against an OS configuration that you want to replicate across your entire node pool.
Finally, we begin the long-running task of running vmss-prototype against the updated node:
$ helm install --repo https://jackfrancis.github.io/kamino/ update-from-k8s-agentpool1-26100436-vmss000000 vmss-prototype --namespace default --set kamino.scheduleOnControlPlane=true --set kamino.newUpdatedNodes=10 --set kamino.targetNode=k8s-agentpool1-26100436-vmss000000
NAME: update-from-k8s-agentpool1-26100436-vmss000000
LAST DEPLOYED: Fri Jan 8 13:04:57 2021
NAMESPACE: default
STATUS: deployed
REVISION: 1
TEST SUITE: NoneNote in the above helm install invocation, we include the --set kamino.newUpdatedNodes=10 option. We do this to easily demonstrate the effects of building new nodes in the VMSS node pool from the target node.
Before long, we'll see that node once again go out of service due to vmss-prototype needing to deallocate and take a snapshot image of its OS disk:
$ k get nodes -o wide -w
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
k8s-agentpool1-26100436-vmss000000 Ready agent 36m v1.20.1 10.240.0.4 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000001 Ready agent 35m v1.20.1 10.240.0.35 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000002 Ready agent 35m v1.20.1 10.240.0.66 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000003 Ready agent 36m v1.20.1 10.240.0.97 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000004 Ready agent 36m v1.20.1 10.240.0.128 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000005 Ready agent 36m v1.20.1 10.240.0.159 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000006 Ready agent 36m v1.20.1 10.240.0.190 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000007 Ready agent 35m v1.20.1 10.240.0.221 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000008 Ready agent 36m v1.20.1 10.240.0.252 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000009 Ready agent 36m v1.20.1 10.240.1.27 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-master-26100436-0 Ready master 36m v1.20.1 10.255.255.5 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000003 Ready agent 36m v1.20.1 10.240.0.97 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000000 Ready agent 36m v1.20.1 10.240.0.4 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000000 Ready,SchedulingDisabled agent 36m v1.20.1 10.240.0.4 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14Eventually, after the OS disk image snapshot is taken of that node VMSS instance, the instance will be deleted, and the node will be permanently removed from the cluster:
$ k get node k8s-agentpool1-26100436-vmss000000
Error from server (NotFound): nodes "k8s-agentpool1-26100436-vmss000000" not foundIt takes a long time (between 30 mins and 2 hours) to create and replicate a new Shared Image Gallery Image (which is the resource type we use to re-use the OS image snapshot across future VMSS instances). Take a break and relax. Eventually, the entire progression of vmss-prototype can be viewed via the pod logs:
$ k logs kamino-gen-k8s-agentpool1-26100436-vmss-l4gzw -f
CMD: ['/usr/bin/vmss-prototype' '--in-cluster' '--log-level' 'INFO' 'update' '--target-node' 'k8s-agentpool1-26100436-vmss000000' '--new-updated-nodes' '10' '--grace-period' '300' '--max-history' '3']
INFO: ===> Executing command: ['az' 'cloud' 'set' '--name' 'AzureCloud']
INFO: ===> Executing command: ['az' 'login' '--identity']
INFO: ===> Executing command: ['az' 'account' 'set' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce']
INFO: ===> Executing command: ['kubectl' 'get' 'node' 'k8s-agentpool1-26100436-vmss000000']
INFO: ===> Executing command: ['az' 'sig' 'show' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--gallery-name' 'SIG_kubernetes_westus2_17813']
INFO: ===> Executing command: ['az' 'sig' 'create' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--gallery-name' 'SIG_kubernetes_westus2_17813' '--description' 'Kamino VMSS images']
INFO: Processing VMSS k8s-agentpool1-26100436-vmss
INFO: ===> Executing command: ['az' 'sig' 'image-definition' 'show' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--gallery-name' 'SIG_kubernetes_westus2_17813' '--gallery-image-definition' 'kamino-k8s-agentpool1-26100436-vmss-prototype']
INFO: ===> Executing command: ['az' 'sig' 'image-definition' 'create' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--gallery-name' 'SIG_kubernetes_westus2_17813' '--gallery-image-definition' 'kamino-k8s-agentpool1-26100436-vmss-prototype' '--publisher' 'VMSS-Prototype-Pattern' '--offer' 'kubernetes-westus2-17813' '--sku' 'k8s-agentpool1-26100436-vmss' '--os-type' 'Linux' '--os-state' 'generalized']
INFO: ===> Executing command: ['az' 'sig' 'image-version' 'list' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--gallery-name' 'SIG_kubernetes_westus2_17813' '--gallery-image-definition' 'kamino-k8s-agentpool1-26100436-vmss-prototype']
INFO: ===> Executing command: ['az' 'snapshot' 'show' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--name' 'snapshot_k8s-agentpool1-26100436-vmss']
INFO: ===> Executing command: ['az' 'vmss' 'show' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--name' 'k8s-agentpool1-26100436-vmss' '--instance-id' '0']
INFO: ===> Executing command: ['kubectl' 'annotate' 'node' 'k8s-agentpool1-26100436-vmss000000' 'cluster-autoscaler.kubernetes.io/scale-down-disabled=true' '--overwrite']
INFO: ===> Executing command: ['kubectl' 'cordon' 'k8s-agentpool1-26100436-vmss000000']
INFO: ===> Executing command: ['kubectl' 'drain' '--ignore-daemonsets' '--delete-local-data' '--force' '--grace-period' '300' '--timeout' '900s' 'k8s-agentpool1-26100436-vmss000000']
INFO: ===> Completed in 0.18s: ['kubectl' 'drain' '--ignore-daemonsets' '--delete-local-data' '--force' '--grace-period' '300' '--timeout' '900s' 'k8s-agentpool1-26100436-vmss000000'] # RC=0
INFO: ===> Executing command: ['az' 'vmss' 'deallocate' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--name' 'k8s-agentpool1-26100436-vmss' '--instance-ids' '0']
INFO: ===> Completed in 152.41s: ['az' 'vmss' 'deallocate' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--name' 'k8s-agentpool1-26100436-vmss' '--instance-ids' '0'] # RC=0
INFO: ===> Executing command: ['az' 'snapshot' 'create' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--name' 'snapshot_k8s-agentpool1-26100436-vmss' '--source' '/subscriptions/aa3d3369-e814-4495-899d-d31e8d7d09ce/resourceGroups/kubernetes-westus2-17813/providers/Microsoft.Compute/disks/k8s-agentpool1-26100k8s-agentpool1-261004OS__1_895f47c2b4bb474a8eb24b32452b94b2' '--tags' 'BuiltFrom=k8s-agentpool1-26100436-vmss000000' 'BuiltAt=2021-01-08 21:09:34.255642']
INFO: ===> Executing command: ['az' 'vmss' 'delete-instances' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--name' 'k8s-agentpool1-26100436-vmss' '--instance-ids' '0' '--no-wait']
INFO: ===> Executing command: ['kubectl' 'uncordon' 'k8s-agentpool1-26100436-vmss000000']
INFO: ===> Executing command: ['kubectl' 'annotate' 'node' 'k8s-agentpool1-26100436-vmss000000' 'cluster-autoscaler.kubernetes.io/scale-down-disabled-']
INFO: Creating sig image version - this can take quite a long time...
INFO: ===> Executing command: ['az' 'sig' 'image-version' 'create' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--gallery-name' 'SIG_kubernetes_westus2_17813' '--gallery-image-definition' 'kamino-k8s-agentpool1-26100436-vmss-prototype' '--gallery-image-version' '2021.01.08' '--replica-count' '3' '--os-snapshot' 'snapshot_k8s-agentpool1-26100436-vmss' '--tags' 'BuiltFrom=k8s-agentpool1-26100436-vmss000000' 'BuiltAt=2021-01-08 21:09:34.255642' '--storage-account-type' 'Standard_ZRS']
INFO: ===> Completed in 5291.25s: ['az' 'sig' 'image-version' 'create' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--gallery-name' 'SIG_kubernetes_westus2_17813' '--gallery-image-definition' 'kamino-k8s-agentpool1-26100436-vmss-prototype' '--gallery-image-version' '2021.01.08' '--replica-count' '3' '--os-snapshot' 'snapshot_k8s-agentpool1-26100436-vmss' '--tags' 'BuiltFrom=k8s-agentpool1-26100436-vmss000000' 'BuiltAt=2021-01-08 21:09:34.255642' '--storage-account-type' 'Standard_ZRS'] # RC=0
INFO: ===> Executing command: ['az' 'snapshot' 'delete' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--name' 'snapshot_k8s-agentpool1-26100436-vmss']
INFO: Latest image: /subscriptions/aa3d3369-e814-4495-899d-d31e8d7d09ce/resourceGroups/kubernetes-westus2-17813/providers/Microsoft.Compute/galleries/SIG_kubernetes_westus2_17813/images/kamino-k8s-agentpool1-26100436-vmss-prototype/versions/2021.01.08
INFO: ===> Executing command: ['az' 'sig' 'image-version' 'list' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--gallery-name' 'SIG_kubernetes_westus2_17813' '--gallery-image-definition' 'kamino-k8s-agentpool1-26100436-vmss-prototype']
INFO: ===> Executing command: ['az' 'vmss' 'show' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--name' 'k8s-agentpool1-26100436-vmss']
INFO: ===> Executing command: ['az' 'vmss' 'update' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--name' 'k8s-agentpool1-26100436-vmss' '--set' 'virtualMachineProfile.storageProfile.imageReference.id=/subscriptions/aa3d3369-e814-4495-899d-d31e8d7d09ce/resourceGroups/kubernetes-westus2-17813/providers/Microsoft.Compute/galleries/SIG_kubernetes_westus2_17813/images/kamino-k8s-agentpool1-26100436-vmss-prototype' 'virtualMachineProfile.storageProfile.imageReference.sku=null' 'virtualMachineProfile.storageProfile.imageReference.offer=null' 'virtualMachineProfile.storageProfile.imageReference.publisher=null' 'virtualMachineProfile.storageProfile.imageReference.version=null' 'virtualMachineProfile.osProfile.customData=I2Nsb3VkLWNvbmZpZwo=']
INFO: ===> Executing command: ['az' 'vmss' 'show' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--name' 'k8s-agentpool1-26100436-vmss']
INFO: ===> Executing command: ['az' 'vmss' 'extension' 'list' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--vmss-name' 'k8s-agentpool1-26100436-vmss']
INFO: ===> Executing command: ['az' 'vmss' 'extension' 'delete' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--vmss-name' 'k8s-agentpool1-26100436-vmss' '--name' 'vmssCSE']
INFO: ===> Executing command: ['az' 'vmss' 'show' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--name' 'k8s-agentpool1-26100436-vmss']
INFO: ===> Executing command: ['az' 'vmss' 'update' '--subscription' 'aa3d3369-e814-4495-899d-d31e8d7d09ce' '--resource-group' 'kubernetes-westus2-17813' '--name' 'k8s-agentpool1-26100436-vmss' '--set' 'sku.capacity=19' '--no-wait'](Narrator: "A good while later...")
We now see our 10 new nodes, as requested by the --set kamino.newUpdatedNodes=10 option:
$ k get nodes -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
k8s-agentpool1-26100436-vmss000001 Ready agent 134m v1.20.1 10.240.0.35 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000002 Ready agent 133m v1.20.1 10.240.0.66 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000003 Ready agent 134m v1.20.1 10.240.0.97 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000004 Ready agent 134m v1.20.1 10.240.0.128 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000005 Ready agent 134m v1.20.1 10.240.0.159 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000006 Ready agent 134m v1.20.1 10.240.0.190 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000007 Ready agent 134m v1.20.1 10.240.0.221 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000008 Ready agent 134m v1.20.1 10.240.0.252 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000009 Ready agent 134m v1.20.1 10.240.1.27 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000a Ready agent 3m28s v1.20.1 10.240.0.4 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000b Ready agent 3m18s v1.20.1 10.240.1.88 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000c Ready agent 3m14s v1.20.1 10.240.1.119 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000d Ready agent 3m25s v1.20.1 10.240.1.150 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000e Ready agent 3m18s v1.20.1 10.240.1.181 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000f Ready agent 3m28s v1.20.1 10.240.1.212 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000g Ready agent 3m20s v1.20.1 10.240.1.243 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000h Ready agent 2m14s v1.20.1 10.240.2.18 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000i Ready agent 3m28s v1.20.1 10.240.2.49 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000j Ready agent 3m48s v1.20.1 10.240.2.80 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-master-26100436-0 Ready master 134m v1.20.1 10.255.255.5 <nonNow, let's confirm that these new nodes are all running the latest bits!
$ for i in {a..j}; do ssh k8s-agentpool1-26100436-vmss00000$i "sudo apt list --upgradable | wc -l && ls -la /var/log/vmss-prototype-was-here"; done
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
1
-rw-r----- 1 root root 0 Jan 8 20:58 /var/log/vmss-prototype-was-here
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
1
-rw-r----- 1 root root 0 Jan 8 20:58 /var/log/vmss-prototype-was-here
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
1
-rw-r----- 1 root root 0 Jan 8 20:58 /var/log/vmss-prototype-was-here
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
1
-rw-r----- 1 root root 0 Jan 8 20:58 /var/log/vmss-prototype-was-here
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
1
-rw-r----- 1 root root 0 Jan 8 20:58 /var/log/vmss-prototype-was-here
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
1
-rw-r----- 1 root root 0 Jan 8 20:58 /var/log/vmss-prototype-was-here
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
1
-rw-r----- 1 root root 0 Jan 8 20:58 /var/log/vmss-prototype-was-here
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
1
-rw-r----- 1 root root 0 Jan 8 20:58 /var/log/vmss-prototype-was-here
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
1
-rw-r----- 1 root root 0 Jan 8 20:58 /var/log/vmss-prototype-was-here
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
1
-rw-r----- 1 root root 0 Jan 8 20:58 /var/log/vmss-prototype-was-hereEverything is looking good. apt is telling us that we don't have any updates (inferred by counting the number of stdout lines). Compare again to one of the original nodes:
$ ssh k8s-agentpool1-26100436-vmss000001 "sudo apt list --upgradable | wc -l && ls -la /var/log/vmss-prototype-was-here"
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
42
ls: cannot access '/var/log/vmss-prototype-was-here': No such file or directoryJust to prove that we've meaningfully updated the VMSS model for this node pool for future scale out operations, let's do a simple scale out by one. There are many ways to do this; we'll demonstrate using the az command line. Recall that we originally begun this exercise on a cluster with a VMSS node pool of 10 nodes. We then installed a release of vmss-prototype via helm using the --set kamino.newUpdatedNodes=10 option. During the execution of that vmss-prototype job we lost one node (the target node, in order to deallocation and grab a snapshot of its OS disk image), and then added 10 more. Which means we now have 19. So we'll set the VMSS capacity to 20 to increase the count by 1:
$ az vmss update --resource-group kubernetes-westus2-17813 --name k8s-agentpool1-26100436-vmss --set sku.capacity=20 --no-wait(Again, we're using the name of the resource group, and of the VMSS, that happen to represent the example cluster here.)
By waiting for the node to arrive, we can easily identify it:
$ k get nodes -o wide -w
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
k8s-agentpool1-26100436-vmss000001 Ready agent 149m v1.20.1 10.240.0.35 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000002 Ready agent 148m v1.20.1 10.240.0.66 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000003 Ready agent 149m v1.20.1 10.240.0.97 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000004 Ready agent 149m v1.20.1 10.240.0.128 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000005 Ready agent 149m v1.20.1 10.240.0.159 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000006 Ready agent 149m v1.20.1 10.240.0.190 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000007 Ready agent 149m v1.20.1 10.240.0.221 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000008 Ready agent 149m v1.20.1 10.240.0.252 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000009 Ready agent 149m v1.20.1 10.240.1.27 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000a Ready agent 18m v1.20.1 10.240.0.4 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000b Ready agent 18m v1.20.1 10.240.1.88 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000c Ready agent 18m v1.20.1 10.240.1.119 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000d Ready agent 18m v1.20.1 10.240.1.150 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000e Ready agent 18m v1.20.1 10.240.1.181 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000f Ready agent 18m v1.20.1 10.240.1.212 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000g Ready agent 18m v1.20.1 10.240.1.243 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000h Ready agent 17m v1.20.1 10.240.2.18 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000i Ready agent 18m v1.20.1 10.240.2.49 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000j Ready agent 18m v1.20.1 10.240.2.80 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-master-26100436-0 Ready master 149m v1.20.1 10.255.255.5 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000k NotReady <none> 0s v1.20.1 10.240.2.111 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000k NotReady <none> 0s v1.20.1 10.240.2.111 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000k NotReady <none> 0s v1.20.1 10.240.2.111 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000k Ready <none> 10s v1.20.1 10.240.2.111 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14That "k"-suffixed node is our mark! Let's validate that it has all the OS updates and sentinel file we're using to positively identify nodes built from the prototype of the original target node:
$ ssh k8s-agentpool1-26100436-vmss00000k "sudo apt list --upgradable | wc -l && ls -la /var/log/vmss-prototype-was-here"
Authorized uses only. All activity may be monitored and reported.
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
1
-rw-r----- 1 root root 0 Jan 8 20:58 /var/log/vmss-prototype-was-hereLooking good!
Finally, we can demonstrate a sort of brute force, rolling "deprecation" of those original, non-patched nodes. First, let's cordon + drain all of them, one-at-a-time, with a 30 second delay in between:
$ for i in `seq 1 9`; do kubectl cordon k8s-agentpool1-26100436-vmss00000$i && kubectl drain --ignore-daemonsets --delete-emptydir-data --force --grace-period 300 --timeout 900s k8s-agentpool1-26100436-vmss00000$i && sleep 30; done
node/k8s-agentpool1-26100436-vmss000001 cordoned
node/k8s-agentpool1-26100436-vmss000001 already cordoned
WARNING: ignoring DaemonSet-managed Pods: kube-system/azure-cni-networkmonitor-bwgxq, kube-system/azure-ip-masq-agent-5drs7, kube-system/blobfuse-flexvol-installer-6hdng, kube-system/csi-secrets-store-provider-azure-6222t, kube-system/csi-secrets-store-x42fn, kube-system/kube-proxy-8dwsj
node/k8s-agentpool1-26100436-vmss000001 drained
node/k8s-agentpool1-26100436-vmss000002 cordoned
node/k8s-agentpool1-26100436-vmss000002 already cordoned
WARNING: ignoring DaemonSet-managed Pods: kube-system/azure-cni-networkmonitor-zd5fh, kube-system/azure-ip-masq-agent-xv8ll, kube-system/blobfuse-flexvol-installer-q9452, kube-system/csi-secrets-store-7zcw4, kube-system/csi-secrets-store-provider-azure-2b6vp, kube-system/kube-proxy-kptk6
node/k8s-agentpool1-26100436-vmss000002 drained
node/k8s-agentpool1-26100436-vmss000003 cordoned
node/k8s-agentpool1-26100436-vmss000003 already cordoned
WARNING: ignoring DaemonSet-managed Pods: kube-system/azure-cni-networkmonitor-f8xvn, kube-system/azure-ip-masq-agent-qvbt6, kube-system/blobfuse-flexvol-installer-kr2kj, kube-system/csi-secrets-store-provider-azure-cr9b5, kube-system/csi-secrets-store-vwvq4, kube-system/kube-proxy-7c5hj
node/k8s-agentpool1-26100436-vmss000003 drained
node/k8s-agentpool1-26100436-vmss000004 cordoned
node/k8s-agentpool1-26100436-vmss000004 already cordoned
WARNING: ignoring DaemonSet-managed Pods: kube-system/azure-cni-networkmonitor-jclsb, kube-system/azure-ip-masq-agent-5zxnc, kube-system/blobfuse-flexvol-installer-pn7fs, kube-system/csi-secrets-store-kc74p, kube-system/csi-secrets-store-provider-azure-mp2bs, kube-system/kube-proxy-drsvf
node/k8s-agentpool1-26100436-vmss000004 drained
node/k8s-agentpool1-26100436-vmss000005 cordoned
node/k8s-agentpool1-26100436-vmss000005 already cordoned
WARNING: ignoring DaemonSet-managed Pods: kube-system/azure-cni-networkmonitor-fcck4, kube-system/azure-ip-masq-agent-2pgdd, kube-system/blobfuse-flexvol-installer-pkdjz, kube-system/csi-secrets-store-24595, kube-system/csi-secrets-store-provider-azure-wvznw, kube-system/kube-proxy-7l8xb
node/k8s-agentpool1-26100436-vmss000005 drained
node/k8s-agentpool1-26100436-vmss000006 cordoned
node/k8s-agentpool1-26100436-vmss000006 already cordoned
WARNING: ignoring DaemonSet-managed Pods: kube-system/azure-cni-networkmonitor-j7nh9, kube-system/azure-ip-masq-agent-km57d, kube-system/blobfuse-flexvol-installer-7tcc8, kube-system/csi-secrets-store-cmtgb, kube-system/csi-secrets-store-provider-azure-dsxmh, kube-system/kube-proxy-8qscw
node/k8s-agentpool1-26100436-vmss000006 drained
node/k8s-agentpool1-26100436-vmss000007 cordoned
node/k8s-agentpool1-26100436-vmss000007 already cordoned
WARNING: ignoring DaemonSet-managed Pods: kube-system/azure-cni-networkmonitor-x9c9x, kube-system/azure-ip-masq-agent-5l4w2, kube-system/blobfuse-flexvol-installer-m7tm2, kube-system/csi-secrets-store-b7qqp, kube-system/csi-secrets-store-provider-azure-9898t, kube-system/kube-proxy-ff2n6
node/k8s-agentpool1-26100436-vmss000007 drained
node/k8s-agentpool1-26100436-vmss000008 cordoned
node/k8s-agentpool1-26100436-vmss000008 already cordoned
WARNING: ignoring DaemonSet-managed Pods: kube-system/azure-cni-networkmonitor-jblk8, kube-system/azure-ip-masq-agent-pk74f, kube-system/blobfuse-flexvol-installer-c5wx8, kube-system/csi-secrets-store-provider-azure-9sgb4, kube-system/csi-secrets-store-xrgwn, kube-system/kube-proxy-rg2qp
node/k8s-agentpool1-26100436-vmss000008 drained
node/k8s-agentpool1-26100436-vmss000009 cordoned
node/k8s-agentpool1-26100436-vmss000009 already cordoned
WARNING: ignoring DaemonSet-managed Pods: kube-system/azure-cni-networkmonitor-lbjqw, kube-system/azure-ip-masq-agent-zp582, kube-system/blobfuse-flexvol-installer-zlskb, kube-system/csi-secrets-store-jfsg6, kube-system/csi-secrets-store-provider-azure-jvzv7, kube-system/kube-proxy-b4gl8
evicting pod kube-system/metrics-server-6c8cc7585b-fvm5f
pod/metrics-server-6c8cc7585b-fvm5f evicted
node/k8s-agentpool1-26100436-vmss000009 evictedNote: this particular recipe for "removing 9 nodes from a cluster and migrating its workloads onto new nodes" is intentionally simplified. There are manifold strategies to do such an operation. In addition, adding 10 (via the vmss-prototype helm release) all of the sudden is not necessarily the right strategy for all cluster scenarios in terms of implementing a "rolling replacement" of "old" with "new" nodes. Hopefully these concrete examples inspire you to implement your own operational gestures appropriate for your environment.
In any event, we should now see that these 9 nodes are no longer actively participating in the cluster:
$ k get nodes -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
k8s-agentpool1-26100436-vmss000001 Ready,SchedulingDisabled agent 165m v1.20.1 10.240.0.35 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000002 Ready,SchedulingDisabled agent 165m v1.20.1 10.240.0.66 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000003 Ready,SchedulingDisabled agent 165m v1.20.1 10.240.0.97 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000004 Ready,SchedulingDisabled agent 165m v1.20.1 10.240.0.128 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000005 Ready,SchedulingDisabled agent 165m v1.20.1 10.240.0.159 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000006 Ready,SchedulingDisabled agent 165m v1.20.1 10.240.0.190 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000007 Ready,SchedulingDisabled agent 165m v1.20.1 10.240.0.221 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000008 Ready,SchedulingDisabled agent 165m v1.20.1 10.240.0.252 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss000009 Ready,SchedulingDisabled agent 165m v1.20.1 10.240.1.27 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000a Ready agent 34m v1.20.1 10.240.0.4 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000b Ready agent 34m v1.20.1 10.240.1.88 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000c Ready agent 34m v1.20.1 10.240.1.119 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000d Ready agent 34m v1.20.1 10.240.1.150 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000e Ready agent 34m v1.20.1 10.240.1.181 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000f Ready agent 34m v1.20.1 10.240.1.212 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000g Ready agent 34m v1.20.1 10.240.1.243 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000h Ready agent 33m v1.20.1 10.240.2.18 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000i Ready agent 34m v1.20.1 10.240.2.49 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000j Ready agent 35m v1.20.1 10.240.2.80 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000k Ready agent 14m v1.20.1 10.240.2.111 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-master-26100436-0 Ready master 166m v1.20.1 10.255.255.5 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14Which means we can safely delete them:
$ for i in `seq 1 9`; do az vmss delete-instances --resource-group kubernetes-westus2-17813 --name k8s-agentpool1-26100436-vmss --instance-ids $i --no-wait; done
$ echo $?
0As it takes some time for Azure to delete the instances, and some more time for the node registration database to remove the nodes from service, we won't see this immediately, but eventually:
$ k get nodes -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
k8s-agentpool1-26100436-vmss00000a Ready agent 47m v1.20.1 10.240.0.4 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000b Ready agent 47m v1.20.1 10.240.1.88 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000c Ready agent 47m v1.20.1 10.240.1.119 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000d Ready agent 47m v1.20.1 10.240.1.150 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000e Ready agent 47m v1.20.1 10.240.1.181 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000f Ready agent 47m v1.20.1 10.240.1.212 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000g Ready agent 47m v1.20.1 10.240.1.243 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000h Ready agent 46m v1.20.1 10.240.2.18 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000i Ready agent 47m v1.20.1 10.240.2.49 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000j Ready agent 47m v1.20.1 10.240.2.80 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-agentpool1-26100436-vmss00000k Ready agent 27m v1.20.1 10.240.2.111 <none> Ubuntu 18.04.5 LTS 5.4.0-1036-azure docker://19.3.14
k8s-master-26100436-0 Ready master 178m v1.20.1 10.255.255.5 <none> Ubuntu 18.04.5 LTS 5.4.0-1032-azure docker://19.3.14We have now replaced our entire set of original nodes running an "old" configuration with fresh, updated nodes. More importantly, we have configured our VMSS so that all new nodes scaled out from this pool will now derive from the updated configuration. This solution is resilient!