Scheduling

Question 1

How do you assign a pod to a node?

Answer 1

Define the nodeName configuration in the spec section of the pod manifest.

Question 2

How do you assign a node to an existing pod?

Answer 2

You convert a YAML Binding manifest to JSON and then POST to the API. eg.

apiVersion: v1
kind: Binding
metadata:
name: nginx
target:
apiVersion: v1
kind: Node
name: node02

Question 3

How do you get pods by specifying a label?

Answer 3

k get pods – selector <label>=<label_value></label_value></label>

Question 4

What is the command for getting all objects in env=prod

Answer 4

k get all –selector=env=prod

Question 5

What is the command to identify the POD which is part of the prod environment, the finance BU and of frontend tier?

Answer 5

k get pod –selector=env=prod,bu=finance,tier=frontend

Question 6

What sets restrictions on what pods can be scheduled on a node?

Answer 6

Taints and tolerations

Question 7

What is the command to taint a node?

Answer 7

k taint nodes <node_name> <key>=<value>:<taint></taint></value></key></node_name>

Taint can be one of the following:
- NoSchedule
- PreferNoSchedule
- NoExecute

Question 8

What are the three types of taints?

Answer 8

• NoSchedule
• PreferNoSchedule
• NoExecute

Question 9

How do you define a toleration?

Answer 9

Inside a manifest’s spec section you define:

spec:
…
tolerations:
- key: “<key_name>"
operator: "Equal"
value: "<key_value>"
effect: "<taint_match>"</taint_match></key_value></key_name>

Question 10

What is the command to label a node?

Answer 10

k label nodes <node_name> <label_key>=<label_value></label_value></label_key></node_name>

Question 11

How do you define a nodeSelector for a pod?

Answer 11

Inside a manifest’s spec section you define:

spec:
…
nodeSelector:
size: <size></size>

Where size = label key value pair

Question 12

What are the types of node affinity?

Answer 12

Available
requiredDuringSchedulingIgnoredDuringExecution
preferredDuringSchedulingIgnoredDuringExecution

Planned
requiredDuringSchedulingRequiredDuringExecution

Question 13

What ensures that one pod is always present on all nodes in a cluster?

Answer 13

Daemon Sets

Question 14

What kind of manifest is almost identical to the ReplicaSet or Deployment definition?

Answer 14

DaemonSet

Question 15

How does the kubelet create a static pod?

Answer 15

By placing a manifest in the pod-manifest-path directory

Question 16

Can multiple copies of a scheduler running at the same time?

Answer 16

No. The leaderElection section of a manifest can define what scheduler is the leader.

Question 17

How do you define what scheduler should be used by a pod?

Answer 17

spec:
…
schedulerName: <scheduler_name></scheduler_name>

Question 18

What happens if you create a pod that defines using a scheduler that is not properly configured?

Answer 18

The pod will remain in a pending state

Question 19

How do you know what scheduler picked up scheduling a pod?

Answer 19

k get events -o wide

Question 20

How do you create seperate profiles for each scheduler using the same binary?

Answer 20

Define the schdulerName under the profiles section. eg.

profiles:
- schedulerName: my-scheduler-2
- schedulerName: my-scheduler-3
- schedulerName: my-scheduler-4

Question 21

How do you disable or enable plugins for schedulers?

Answer 21

profiles:
- schedulerName: my-scheduler-2
plugins:
score:
disabled:
- name: TaintToleration
enabled:
- name: MyCustomPluginA
- name: MyCustomPluginB
- schedulerName: my-scheduler-3
plugins:
prescore:
disabled:
- name: ‘’
score:
enabled:
- name: ‘’
- schedulerName: my-scheduler-4

Question 22

How do you define a priority class?

Answer 22

apiVersion: scheduling.k8s.io/v1
kind: PriorityClass
metadata:
name: high-priority
value: 1000000
globalDefault: false
description: “This should be used to XYZ service pods only”

Question 23

How do you define a priority class on a pod manifest

Answer 23

Add the priorityClassName: <priority_name> to the spec section. eg.

spec:
priorityClassName: <priority_name></priority_name>