Fix AWS CSI scale-up from zero by populating CSI node topology - #10133
Fix AWS CSI scale-up from zero by populating CSI node topology#10133Debasish-87 wants to merge 8 commits into
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📝 WalkthroughWalkthroughThe AWS provider now records EBS attachment limits from instance metadata and no longer creates CSINode data for AWS template nodes. Tests cover missing template CSINode data and existing EFS-only nodes. ChangesAWS CSI node handling
Estimated code review effort: 3 (Moderate) | ~20 minutes Merge Risk: 🟠 High · up to The current implementation can prevent AWS node groups from scaling from zero for workloads using EBS CSI volumes with topology constraints. Merge should wait until CSINode generation is restored conditionally and both EBS-positive and EFS-only cases are covered. Suggested reviewers: 🚥 Pre-merge checks | ✅ 3 | ❌ 2❌ Failed checks (2 warnings)
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In `@cluster-autoscaler/cloudprovider/aws/ec2_instance_types/gen.go`:
- Line 77: Regenerate the checked-in instance-type data from the updated
generator template so every entry in the InstanceTypes map includes its
EBSVolumeLimit value. Commit the generated ec2_instance_types.go output without
altering the generator change or unrelated data.
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cluster-autoscaler/cloudprovider/aws/aws_cloud_provider.gocluster-autoscaler/cloudprovider/aws/aws_cloud_provider_test.gocluster-autoscaler/cloudprovider/aws/aws_manager.gocluster-autoscaler/cloudprovider/aws/aws_manager_test.gocluster-autoscaler/cloudprovider/aws/aws_util.gocluster-autoscaler/cloudprovider/aws/aws_util_test.gocluster-autoscaler/cloudprovider/aws/ec2_instance_types.gocluster-autoscaler/cloudprovider/aws/ec2_instance_types/gen.go
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Inline comments:
In `@cluster-autoscaler/cloudprovider/aws/ec2_instance_types/gen.go`:
- Around line 35-36: Regenerate the checked-in static instance-type data used by
AwsManager.buildCSINodeFromTemplate so each applicable InstanceType literal in
ec2_instance_types.go includes its EBSVolumeLimit. Commit the regenerated file,
preserving the existing runtime metadata and ensuring CSINodeDriver.Allocatable
can use these limits during scale-up from zero.
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cluster-autoscaler/cloudprovider/aws/ec2_instance_types/gen.go
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Have you had a chance to test this e2e in real cluster btw? The code looks okay fwiw. |
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Yes, I tested this on a real AWS EKS cluster with |
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/test pull-autoscaling-e2e-gci-gce-ca-test |
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/lgtm |
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| driver := storagev1.CSINodeDriver{ | ||
| Name: "ebs.csi.aws.com", |
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IIUC this would make CA start treating a node without the EBS driver as unready (from CA's perspective). CSI drivers are optional cluster addons and may not run on every node group, so I don't think we can just add it to every AWS node template unconditionally.
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Thanks, that's a good point. I agree that we shouldn't assume the EBS CSI driver is present on every AWS node group. I'll look into how we can determine CSI driver applicability for a scale-from-zero template before making this conditional.
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hmm, I would argue that earlier code was better(not perfect). I don't know why we invented all this tag and stuff to handle this.
CSI drivers are optional cluster addons
It depends on the provider. Say for Openshift - CSI driver is not an optional add-on. It is always enabled by default. But that may be beside the point.
I think rather than inventing this new template and stuff, a simpler solution is to return CSINode object with spec.drivers empty. This will allow check in CA for readiness to skip the CSI check and consider node as ready if all other things on the node are ready.
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Thanks, that makes sense. I agree that introducing a new AWS-specific csi-driver template tag adds complexity.
Just to confirm my understanding: are you suggesting that for the scale-from-zero template we should return a CSINode with an empty spec.drivers, rather than trying to determine or declare specific CSI drivers?
If so, I'll rework the implementation accordingly and remove the csi-driver tag, parsing, and related AWS-specific CSI detection logic.
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hmm, hang on - now that I think of, we have no other choice than to use some kind of tags on asgs to determine if CSI drivers will be installed if someone is running CA with AWS cloudprovider integration. In Openshift we use cluster-apis which solves this via tags too.
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I will let @torredil confirm if tags logic makes sense.
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I ended up at the same conclusion @gnufied, at scale zero CSINode doesn't exist so the expected drivers need to be declared on the node group itself. Cluster API does something similar, this looks correct to me.
@Debasish-87 before landing this we also need to test an existing node group where another CSI driver (such as EFS) is registered but |
Got it. I'll test this scenario on an existing node group where EFS CSI is registered but ebs.csi.aws.com is not, and verify that CA doesn't incorrectly assume the EBS CSI driver is available. |
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Inline comments:
In `@cluster-autoscaler/cloudprovider/aws/aws_manager.go`:
- Around line 349-351: Restore conditional CSINode creation in the relevant AWS
manager template path: use cluster or node-group data to confirm ebs.csi.aws.com
before returning a CSINode, while continuing to return nil when the driver is
absent (including EFS-only templates). Ensure the non-nil result reaches
TemplateNodeInfo.SetCSINode, and update tests to cover both an EBS-enabled empty
node group and an EFS-only node group.
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cluster-autoscaler/cloudprovider/aws/aws_cloud_provider_test.gocluster-autoscaler/cloudprovider/aws/aws_manager.gocluster-autoscaler/cloudprovider/aws/aws_manager_test.go
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Hi @torredil, I’ve updated the implementation based on your feedback. CSI drivers are now explicitly declared through the AWS node-template I’ve added regression coverage for the EFS-only case and the ASG/Managed Node Group CSI tag precedence scenarios. When you have a chance, could you please take another look and let me know if this addresses your concern or if any further changes are needed? Thanks! |
| The tag key is: | ||
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| `k8s.io/cluster-autoscaler/node-template/csi-driver` | ||
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Where did this tag key/value come from? Did we just invent this in this PR?
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You're right — this tag key/value is introduced by this PR.
It is not inferred from EBSVolumeLimit or an existing AWS tag. We need an explicit node-template declaration because CSI drivers are optional and EBSVolumeLimit only represents EC2 attachment capacity, not whether the EBS CSI driver is installed.
The tag is used only to declare CSI driver applicability for scale-from-zero simulation. For EKS Managed Node Groups, we also honor the same tag from DescribeNodegroup with MNG-over-ASG precedence.
I documented the new tag and its intended semantics in the AWS provider README.
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@Debasish-87 one of the conventions we use in Kubernetes on comments is, not to mark a comment as resolved until both reviewer and author agree on a resolution. Marking a review comment as resolved prematurely hides the conversation thread from reviewers view and makes it harder to discover outstanding issues on a review. |
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Understood. I’ll leave review threads unresolved until we agree on the resolution. Thanks for pointing this out. |
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/lgtm |
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/assign @jackfrancis @elmiko |
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Hi @jackfrancis and @elmiko, I hope you’re doing well. I wanted to kindly follow up on this PR, as it was assigned to you for review. Since the last update, the implementation has been refined based on the review discussion. The current approach uses the explicit I’ve also added the related regression coverage, including the EFS-only case and ASG/Managed Node Group tag precedence scenarios, and tested the EBS CSI scale-from-zero path on a real EKS environment. Whenever you have some time, I’d really appreciate it if you could take a look at the latest changes and let me know if you have any concerns or if anything else should be addressed. Thank you very much for your time and review. |
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i'm not overly familiar with the aws provider, but nothing here seems objectionable to me.
/lgtm
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Summary
Fix AWS Cluster Autoscaler scale-up from zero for node groups using CSI-backed volumes with topology constraints.
When an AWS node group has zero running nodes, Cluster Autoscaler builds a synthetic
NodeInfofrom the ASG instance template. Previously, this syntheticNodeInfodid not include the correspondingCSINodeinformation, resulting in incomplete CSI capability and topology information during scheduling simulation.This change allows AWS node templates to explicitly declare their CSI drivers and uses that information to construct and attach a synthetic
CSINodeto the generatedNodeInfo.Fixes: #10131
Problem
AwsNodeGroup.TemplateNodeInfo()creates a synthetic node for scale-up-from-zero simulation but previously did not attach a correspondingCSINode.As a result, pods using CSI-backed volumes with topology constraints could be evaluated against incomplete node information when the node group had zero running nodes.
At the same time, an EC2 instance type's EBS attachment limit alone is not sufficient evidence that the EBS CSI driver is installed on the node group. Automatically creating an EBS
CSINodefrom the instance type could therefore incorrectly advertiseebs.csi.aws.comcapability.Solution
k8s.io/cluster-autoscaler/node-template/csi-driverCSINodeonly when CSI drivers are explicitly declared by the node template.CSINodeto the syntheticNodeInfoused for scale-up-from-zero simulation.Allocatable.Countfrom the EC2 instance type'sEBSVolumeLimitwhen the limit is available.csi-drivertag returned byDescribeNodegroupwhen present, following the existing Managed Node Group tag precedence behavior.csi-drivertag when the Managed Node Group tag is absent or the Managed Node Group lookup fails.=or whitespace.EBS Volume Attachment Limits
The EC2 instance type metadata now carries the EBS volume attachment limit required to populate the synthetic EBS
CSINodeDriver.The instance type generator has also been updated so
EBSVolumeLimitis included in generated instance metadata.This allows scale-up-from-zero scheduling simulation to account for the EBS volume attachment capacity of the target instance type without assuming that the EBS CSI driver is installed.
Regression Coverage
The test suite covers:
CSINodeCSINodewith the expected volume limitTesting
The AWS provider test suite passes:
go test ./cloudprovider/awsResult:
ok k8s.io/autoscaler/cluster-autoscaler/cloudprovider/awsAlso verified:
gofmtgit diff --checkThe working tree was clean after the changes were committed.
Commit:
00a2c93c3 Support explicit CSI drivers in AWS node templatesRelease Notes
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