Adding temporary multizone-nodepool support for CAS

[aagusuab]

What type of PR is this?

What this PR does / why we need it:

This PR will prevent error once cluster-autoscaler is scaling the multi-zone nodepool from zero.
This is necessary because currently when we are trying to create a node template from the multi-zone nodepool, we create the zone-labels "topology.kubernetes.io/zone " where the label is "eastus-1__eastus-2__eastus3".
However, this label is not recognized by some affinities.
With this PR, Cluster Autoscaler will create node templates using any random zone that the VMSS contains. However, this zone isn't the zone VMSS assigns VMs with. The VMSS will decide separately#### Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[k8s-ci-robot]

Hi @aagusuab. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[nojnhuh]

/ok-to-test

[willie-yao]

Looks good, just a minor nit.

[willie-yao]

Suggested change

	//Picks random zones for Multi-zone nodepool when scaling from zero.
	//This random zone will not be the same as the zone of the VMSS that is being created, the purpose of creating
	//the node template with random zone is to initiate scaling from zero on the multi-zone nodepool.
	//Note that the if the customer is to have some pod affinity picking exact zone, this logic won't work.
	//For now, discourage the customers from using podAffinity to pick the availability zones.
	// Picks random zones for Multi-zone nodepool when scaling from zero.
	// This random zone will not be the same as the zone of the VMSS that is being created, the purpose of creating
	// the node template with random zone is to initiate scaling from zero on the multi-zone nodepool.
	// Note that the if the customer is to have some pod affinity picking exact zone, this logic won't work.
	// For now, discourage the customers from using podAffinity to pick the availability zones.

[Bryce-Soghigian]

lol

[nojnhuh]

This PR will prevent error once cluster-autoscaler is scaling the multi-zone nodepool from zero.

Just for my own understanding, can you give an example of one of these errors?

This is necessary because currently when we are trying to create a node template from the multi-zone nodepool, we create the zone-labels "topology.kubernetes.io/zone " where the label is "eastus-1__eastus-2__eastus3". However, this label is not recognized by some affinities.

Also to help me understand, which affinities exactly are you referring to here?

[aagusuab]

This PR will prevent error once cluster-autoscaler is scaling the multi-zone nodepool from zero.

Just for my own understanding, can you give an example of one of these errors?

This is necessary because currently when we are trying to create a node template from the multi-zone nodepool, we create the zone-labels "topology.kubernetes.io/zone " where the label is "eastus-1__eastus-2__eastus3". However, this label is not recognized by some affinities.

Also to help me understand, which affinities exactly are you referring to here?

Sure, @nojnhuh!
One of the customers tried to specify an availability zone for one of the nodes, setting
topology.disk.csi.azure.com/zone=zone1

This caused an error because cluster autoscaler currently takes in multiple zones such that:
topology.disk.csi.azure.com/zone=zone1__zone2__zone3 (to account for multiple zones)

and the initial node label of "zone1" is not recognized by the multi-zone node label.

Therefore, we are removing this zone1__zone2__zone3 (or any similar availability_zone setup), and setting up the
topology.disk.csi.azure.com/zone=. to be of a random zone (this occurs when node template is being created/setup).
This does not affect the actual node label, as what determines the actual node label / zone is cloud provider, not the node template.

[tallaxes]

For now, discourage the customers from using podAffinity to pick the availability zones
"... if using multi-zone nodepool" (but probably clear from context)

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aagusuab, Bryce-Soghigian, comtalyst, tallaxes

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• cluster-autoscaler/cloudprovider/azure/OWNERS [Bryce-Soghigian,tallaxes]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[tallaxes]

/lgtm

[aagusuab]

/cherry-pick cluster-autoscaler-release-1.27
/cherry-pick cluster-autoscaler-release-1.28
/cherry-pick cluster-autoscaler-release-1.29
/cherry-pick cluster-autoscaler-release-1.30

[k8s-infra-cherrypick-robot]

@aagusuab: only kubernetes org members may request cherry picks. If you are already part of the org, make sure to change your membership to public. Otherwise you can still do the cherry-pick manually.

In response to this:

/cherry-pick cluster-autoscaler-release-1.27
/cherry-pick cluster-autoscaler-release-1.28
/cherry-pick cluster-autoscaler-release-1.29
/cherry-pick cluster-autoscaler-release-1.30

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[comtalyst]

/cherry-pick cluster-autoscaler-release-1.27
/cherry-pick cluster-autoscaler-release-1.28
/cherry-pick cluster-autoscaler-release-1.29
/cherry-pick cluster-autoscaler-release-1.30

[k8s-infra-cherrypick-robot]

@comtalyst: #7013 failed to apply on top of branch "cluster-autoscaler-release-1.27":

Applying: Adding temporary multizone-nodepool support for CAS
Using index info to reconstruct a base tree...
M	cluster-autoscaler/cloudprovider/azure/azure_template.go
M	cluster-autoscaler/cloudprovider/azure/azure_template_test.go
Falling back to patching base and 3-way merge...
Auto-merging cluster-autoscaler/cloudprovider/azure/azure_template_test.go
CONFLICT (content): Merge conflict in cluster-autoscaler/cloudprovider/azure/azure_template_test.go
Auto-merging cluster-autoscaler/cloudprovider/azure/azure_template.go
CONFLICT (content): Merge conflict in cluster-autoscaler/cloudprovider/azure/azure_template.go
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0001 Adding temporary multizone-nodepool support for CAS
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".

In response to this:

/cherry-pick cluster-autoscaler-release-1.27
/cherry-pick cluster-autoscaler-release-1.28
/cherry-pick cluster-autoscaler-release-1.29
/cherry-pick cluster-autoscaler-release-1.30

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[comtalyst]

/cherry-pick cluster-autoscaler-release-1.30
/cherry-pick cluster-autoscaler-release-1.29
/cherry-pick cluster-autoscaler-release-1.28

[k8s-infra-cherrypick-robot]

@comtalyst: new pull request created: #7190

In response to this:

/cherry-pick cluster-autoscaler-release-1.30
/cherry-pick cluster-autoscaler-release-1.29
/cherry-pick cluster-autoscaler-release-1.28

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[comtalyst]

/cherry-pick cluster-autoscaler-release-1.29

[comtalyst]

/cherry-pick cluster-autoscaler-release-1.28

[k8s-infra-cherrypick-robot]

@comtalyst: new pull request created: #7192

In response to this:

/cherry-pick cluster-autoscaler-release-1.29

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[k8s-infra-cherrypick-robot]

@comtalyst: #7013 failed to apply on top of branch "cluster-autoscaler-release-1.28":

Applying: Adding temporary multizone-nodepool support for CAS
Using index info to reconstruct a base tree...
M	cluster-autoscaler/cloudprovider/azure/azure_template.go
M	cluster-autoscaler/cloudprovider/azure/azure_template_test.go
Falling back to patching base and 3-way merge...
Auto-merging cluster-autoscaler/cloudprovider/azure/azure_template_test.go
CONFLICT (content): Merge conflict in cluster-autoscaler/cloudprovider/azure/azure_template_test.go
Auto-merging cluster-autoscaler/cloudprovider/azure/azure_template.go
CONFLICT (content): Merge conflict in cluster-autoscaler/cloudprovider/azure/azure_template.go
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0001 Adding temporary multizone-nodepool support for CAS
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".

In response to this:

/cherry-pick cluster-autoscaler-release-1.28

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.