Azure-docs: Autoscaling not enabled

[bramvdklinkenberg]

I created a cluster with the command below:

az aks create --resource-group RG20BRAM-DEV --name AKS20BRAMDEV --location westeurope --node-count 2 --node-vm-size Standard_E2s_v3 --dns-name-prefix bramdev --kubernetes-version 1.12.5 --service-principal ${SP} --client-secret ${SECRET} --aad-client-app-id ${AAD_CLIENT} --aad-server-app-id ${AAD_SERVER} --aad-server-app-secret ${AAD_SECRET} --aad-tenant-id ${TENANT} --no-ssh-key --skip-subnet-role-assignment --network-policy calico --network-plugin azure --service-cidr 10.0.0.0/16 --dns-service-ip 10.0.0.10 --docker-bridge-address 172.17.0.1/16 --vnet-subnet-id ${SUBNET} --enable-vmss --enable-cluster-autoscaler --min-count 2 --max-count 4 --enable-addons monitoring --workspace-resource
-id ${WORKSPACE}

The cluster is created and has a vmss but autoscaling is not enabled and configured as passed in the command. I have to manually enable autoscaling and configure min, max and default amount of nodes.

I tried it several times and same issue every time.

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Document Details

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• ID: 077f1bb5-2ba9-490c-2c6e-0de292266539
• Version Independent ID: 0fd87b4f-88a4-c2eb-3ebc-f2b113ac203c
• Content: Use the cluster autoscaler in Azure Kubernetes Service (AKS)
• Content Source: articles/aks/cluster-autoscaler.md
• Service: container-service
• GitHub Login: @iainfoulds
• Microsoft Alias: iainfou

[bramvdklinkenberg]

I noticed that eventhough it seems that scaling is not enabled it actually does. I created a deployment and set some resource requests so I would be sure it needed extra resources and it actually scaled the amount of nodes.
So in the portal it seems to be disabled but it actually is enabled somewhere in the backend/background.

[jakaruna-MSFT]

Thanks for the feedback! We are currently checking and will update you shortly.

[bramvdklinkenberg]

I am also wondering based on which metrics it scales. If you enable autoscaling in the portal you need to provide some metric based rules for scaling. These metric based rules is not something that be added to the az aks command.

Another things when I enable autoscaling via the portal it overides settings I provided with the cli.

[bramvdklinkenberg]

So, some more findings...
Via the cli I enabled scaling, the portal doesn't show that but scaling works... so I thought let's try "enabling" it via the portal as well and then delete autoscaling via the cli. This has the opposite effect, in the portal it shows enabled but it is actually disabled on the background because it didn't scale anymore after I applied the deployment again.

[bramvdklinkenberg]

So after I disabled it via the cli it still showed enabled in the portal, but scaling didn't work anymore. So I disabled it in the portal as well and after enabling it again via the az cli it also showed as enabled in the portal.

[jakaruna-MSFT]

@bramvdklinkenberg Thanks for your interest in debugging this scenario.
Cluster autoscaler deploys a pod in the AKS. That pod monitors for the Pods which are in pending state due to no space in the existing cluster. If it finds any pods, Then it triggers the scaling process.
Please check this link for more information.

[bramvdklinkenberg]

Hi @jakaruna-MSFT , thanks for the info. But it also scales back when I scale down the deployment.
Does it check any metrics for that?

Curious about the other issues I found.

[jakaruna-MSFT]

@bramvdklinkenberg It also checks for the underutilized nodes.
It takes care of both scaling up and down as well.
https://github.com/kubernetes/autoscaler/blob/master/cluster-autoscaler/README.md#introduction

[iainfoulds]

From the doc:

The VMSS autoscaling is not what's used here. It's the Kubernetes cluster autoscaler. The two are quite different. The link to the Kubernetes cluster autoscaler that @jakaruna-MSFT shared provides information what's happening.

[kasunsjc]

Hi Guys

Does anyone getting bellow error

kasun@Azure:~$ az aks update --resource-group promakscluster --name promakscluster --enable-cluster-autoscaler --min-count 1 --max-count 10 az aks: 'update' is not in the 'az aks' command group. See 'az aks --help'.

Check with following doc and can't find a update parameter
https://docs.microsoft.com/en-us/cli/azure/aks?view=azure-cli-latest

[iainfoulds]

@kasunsjc That command is part of the aks-preview CLI extension. From the doc:

[jakaruna-MSFT]

@bramvdklinkenberg @kasunsjc I will close this out for now. If you need additional help please let me know and we can reopen and continue.