Difference between revisions of "Kubernetes/Scheduling"
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*[https://kubernetes.io/docs/concepts/configuration/assign-pod-node/ Assigning a Pod to a Node] | *[https://kubernetes.io/docs/concepts/configuration/assign-pod-node/ Assigning a Pod to a Node] | ||
*[https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#affinity-and-anti-affinity Pod and Node Affinity Rules] | *[https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#affinity-and-anti-affinity Pod and Node Affinity Rules] | ||
*[https://kubernetes.io/docs/tasks/administer-cluster/configure-multiple-schedulers/ Configure Multiple Schedulers (our-own)] |
Revision as of 09:08, 19 July 2019
Default scheduler rules
- Identify if a node has adequate hardware resources
- Check if a node is running out of resources. check for memory or disk pressure conditions
- Check if a pod schedule is scheduled to a node by a name
- Check if a node has a label matching node selector in a pod spec
- Check if a pod is requesting to bound to a specific host port and if so, does the node have that port available
- Check if a pod is requesting a certain type of volume be mounted and if other pods are using the same volume
- Check if a pod tolerates taints of the node, eg. master nodes is tainted with "noSchedule"
- Check if a pod or a node affinity rules and checking if scheduling the pod would break these rules
- If there is more than one node could schedule a pod, the scheduler priorities the nodes and choose the best one. If they have the same priority it chooses in round-robin fashion.
Label nodes
kubectl label node worker1.acme.com share-type=dedicated
YAML for the deployment to include the node affinity rules:
apiVersion: extensions/v1beta1 kind: Deployment metadata: name: pref spec: replicas: 5 template: metadata: labels: app: pref spec: affinity: nodeAffinity: preferredDuringSchedulingIgnoredDuringExecution: #all pods,but not current pod on the node - weight: 80 preference: matchExpressions: - key: availability-zone operator: In values: - zone1 - weight: 20 #4 time less priority then AZ preference: matchExpressions: - key: share-type #label key operator: In values: - dedicated #label value containers: - args: - sleep - "999" image: busybox:v1.28.4 name: main