hns-nqs-plugin

NodeQuotaSync Plugin for HNS

The NodeQuotaSync plugin is an extension for HNS.

It enables syncing the root subnamespace quota object and secondary subnamespaces quota objects with the node's allocatable resources in the cluster. It provides support for resources multiplier for over-commit and a reserved resources mechanism, making it easier to remove nodes from the cluster temporarily without affecting the allocatable subnamespaces resources.

Features

• Auto-syncs the quota objects of the root subnamespace and secondary subnamespaces with the matching nodes' allocatable resources.
• Configurable resources multiplier for over-commit.
• Reserved resources mechanism for removing nodes in a safe way.
• Select what type of resource to control
• Control through a Config CRD

Configuration

The NodeQuotaSync plugin is configured using the NodeQuotaConfig CRD:

apiVersion: dana.hns.io/v1alpha1
kind: NodeQuotaConfig
metadata:
  name: example-nodequotaconfig
spec:
  reservedHoursToLive: 24
  controlledResources: ["cpu","ephermal-storage","memory","pods","nvidia.com/gpu"]
  subnamespacesRoots:
    - rootNamespace: cluster-root
      secondaryRoots:
        - labelSelector:
            app: gpu
          name: gpu
          multipliers:
            cpu: "2"
            memory: "2"
        - labelSelector:
            app: cpu-workloads
          name: cpu-workloads
          multipliers:
            memory: "4"

• subnamespaceRoots - defines the cluster's hierarchy;
• rootNamespace - represents the name of the root namespace;
• secondaryRoots - the direct children of the root namespaces with their corresponding node's labelSelector and multipliers.

ReservedResources

The ReservedResources mechanism is a way to ensure there is no resources shortage when dealing with Nodes maintenance.

It works by giving the cluster's admins time to restore the node into the cluster without recalculating the cluster's resources and only removing the node's resources in a controlled way after a pre-set number of hours. This can be configured in the Config CR using the ReservedHoursToLive field.

When we remove one of the nodes from the cluster a ReservedResources field will be added to the CRD status:

  reservedResources:
    - Timestamp: '2023-07-09T07:04:27Z'
      nodeGroup: cpu-workloads
      resources:
        cpu: 3500m
        memory: '61847027712'
        pods: '250'

The cluster's resources will not be updated until the number of hours in the reservedHoursToLive will pass from (starting from Timestamp); afterwards, the node's resources will be removed.