Project: Volcano (Orchestration & Management / Scheduling & Orchestration)
File: how_to_use_nodegroup_plugin.md

Nodegroup plugin is designed to isolate resources by assigning labels to nodes and set node label affinty on Queue. Assign label to node, label key is `volcano.sh/nodegroup-name`. ```shell script kubectl label nodes <nodename> volcano.sh/nodegroup-name=<groupname> ``` Create queue and bind nodegroup to it. ```yaml apiVersion: scheduling.volcano.sh/v1beta1 kind: Queue metadata: name: default spec: reclaimable: true weight: 1 affinity: # added field nodeGroupAffinity: requiredDuringSchedulingIgnoredDuringExecution: <groupname> preferredDuringSchedulingIgnoredDuringExecution: <groupname> nodeGroupAntiAffinity: requiredDuringSchedulingIgnoredDuringExecution: <groupname> preferredDuringSchedulingIgnoredDuringExecution: <groupname> ``` submit vcjob job-1 to default queue. ```shell script $ cat <<EOF | kubectl apply -f - apiVersion: batch.volcano.sh/v1alpha1 kind: Job metadata: name: job-1 spec: minAvailable: 1 schedulerName: volcano queue: default policies: event: PodEvicted action: RestartJob tasks: replicas: 1 name: nginx policies: event: TaskCompleted action: CompleteJob template: spec: containers: command: sleep 10m image: nginx:latest name: nginx resources: requests: cpu: 1 limits: cpu: 1 restartPolicy: Never EOF ``` Query pod information and verify whether the pod has been scheduled on the correct node. The pod should be scheduled on nodes with label `nodeGroupAffinity.requiredDuringSchedulingIgnoredDuringExecution` or `nodeGroupAffinity.preferredDuringSchedulingIgnoredDuringExecution`. If not, the pod should be scheduled on nodes with label of `nodeGroupAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution`. Specifically, the pod must not be scheduled on nodes with the label `nodeGroupAntiAffinity.requiredDuringSchedulingIgnoredDuringExecution`. ```shell script kubectl get po job-1-nginx-0 -o wide ``` The nodegroup design document provides the most detailed information about the node group. There are some tips to help avoid certain issues.These tips are based on a four-nodes cluster and vcjob called job-1: | Node | Label | | | | | node1 | groupname1 | | node2 | groupname2 | | node3 | groupname3 | | node4 | groupname4 | ```yaml apiVersion: batch.volcano.sh/v1alpha1 kind: Job metadata: name: job-1 spec: minAvailable: 1 schedulerName: volcano queue: default policies: event: PodEvicted action: RestartJob tasks: replicas: 1 name: nginx policies: event: TaskCompleted action: CompleteJob template: spec: containers: command: sleep 10m image: nginx:latest name: nginx resources: requests: cpu: 1 limits: cpu: 1 restartPolicy: Never ``` Soft constraints are a subset of hard constraints, including both affinity and anti-affinity. Consider a queue setup as follows: ```yaml apiVersion: scheduling.volcano.sh/v1beta1 kind: Queue metadata: name: default spec: reclaimable: true weight: 1 affinity: # added field nodeGroupAffinity: requiredDuringSchedulingIgnoredDuringExecution: groupname1 gropuname2 preferredDuringSchedulingIgnoredDuringExecution: groupname1 nodeGroupAntiAffinity: requiredDuringSchedulingIgnoredDuringExecution: groupname3 gropuname4 preferredDuringSchedulingIgnoredDuringExecution: groupname3 ``` This implies that tasks in the "default" queue will be scheduled on "groupname1" and "groupname2", with a preference for "groupname1" to run first. Tasks are restricted from running on "groupname3" and "groupname4". However, if the resources in other node groups are insufficient, the task can run on "nodegroup3". If soft constraints do not form a subset of hard constraints, the queue configuration is incorrect, leading to tasks running on "groupname2": ```yaml apiVersion: scheduling.volcano.sh/v1beta1 kind: Queue metadata: name: default spec: reclaimable: true weight: 1 affinity: # added field nodeGroupAffinity: requiredDuringSchedulingIgnoredDuringExecution: gropuname2 preferredDuringSchedulingIgnoredDuringExecution: groupname1 nodeGroupAntiAffinity: requiredDuringSchedulingIgnoredDuringExecution: gropuname4 preferredDuringSchedulingIgnoredDuringExecution: groupname3 ``` If there is a conflict between nodeGroupAffinity and nodeGroupAntiAffinity, nodeGroupAntiAffinity takes higher priority. ```yaml apiVersion: scheduling.volcano.sh/v1beta1 kind: Queue metadata: name: default spec: reclaimable: true weight: 1 affinity: # added field nodeGroupAffinity: requiredDuringSchedulingIgnoredDuringExecution: groupname1 gropuname2 preferredDuringSchedulingIgnoredDuringExecution: groupname1 nodeGroupAntiAffinity: requiredDuringSchedulingIgnoredDuringExecution: groupname1 preferredDuringSchedulingIgnoredDuringExecution: gropuname2 ``` This implies that tasks in the "default" queue can only run on "groupname2". Generally, tasks run on "groupname1" first because it is a soft constraint. However, the scoring function comprises several plugins, so the task may sometimes run on "groupname2". ```yaml apiVersion: scheduling.volcano.sh/v1beta1 kind: Queue metadata: name: default spec: reclaimable: true weight: 1 affinity: # added field nodeGroupAffinity: requiredDuringSchedulingIgnoredDuringExecution: groupname1 gropuname2 preferredDuringSchedulingIgnoredDuringExecution: groupname1 nodeGroupAntiAffinity: requiredDuringSchedulingIgnoredDuringExecution: groupname3 gropuname4 preferredDuringSchedulingIgnoredDuringExecution: groupname3 ```