Pod Design

Question 1

What is the purpose of a label?

Answer 1

Labels can be used to organize and to select subsets of objects. Labels are key/value pairs that are attached to objects, such as pods.

Question 2

What is the purpose of a selector?

Answer 2

Via a label selector, the client/user can identify a set of objects. They allow kubernetes objects to be filtered by their label.

Question 3

In a Pod definition, how are labels applied?

Answer 3

metadata: labels: key1: value1 key2: value2

Question 4

What is the imperative command to select a pod with a label? (e.g. label foo with value bar)

Answer 4

kubectl get po --selector foo=bar

Question 5

In a ReplicaSet definition, how are the pods to be managed by the ReplicaSet selected? (e.g. pods with label foo with value bar)

Answer 5

spec: selector: matchLabels: foo: bar

Question 6

In a Service definition, how are the pods to be exposed by the Service selected? (e.g. pods with label foo and value bar)

Answer 6

spec: selector: foo: bar

Question 7

What is the purpose of annotations?

Answer 7

You can use Kubernetes annotations to attach arbitrary non-identifying metadata to objects

Question 8

In definition files, how are annotations applied to Kubernetes objects? (e.g. an annotation with key foo and value bar)

Answer 8

metadata: annotations: foo: bar

Question 9

What is the imperative command for determining the status of a rollout? (e.g. for deployment named dep1)

Answer 9

kubectl rollout status deployment/dep1

Question 10

What is the imperative command for finding the history of a rollout? (e.g. for a deployment named dep1)

Answer 10

kubectl rollout history deployment/dep1

Question 11

What are the types of deployment strategy?

Answer 11

• recreate (all are destroyed before new are created)
• rolling (objects are destroyed and created one at a time)

Question 12

What is the default deployment strategy?

Answer 12

rolling

Question 13

What is the imperative command for changing the image of a single container deployment? (e.g. deployment named dep1 with an nginx image being updated to nginx:1.9.1)

Answer 13

kubectl set image deployment/dep1 nginx=nginx:1.9.1

Question 14

What is the imperative command for rolling back a deployment? (e.g. deployment named dep1)

Answer 14

kubectl rollout undo deployment/dep1

Question 15

What is the imperative command for getting the history of a particular rollout revision? (e.g. for the second revision of a deployment named dep1)

Answer 15

kubectl rollout history deployment/dep1 --revision=2

Question 16

What is the purpose of a job?

Answer 16

A Job creates one or more Pods and ensures that a specified number of them successfully terminate. They typically carry out a specific task and then finish.

Question 17

Why is a Pod (with default restart policy value) not suitable for a one-off task?

Answer 17

A one-off task will eventually exit and the Pod will move into a completed state. Kubernetes will attempt to restart a pod once it has completed. Restarting, and re-undertaking the task, is not desired.

Question 18

In the Pod definition, how is a OnFailure restart policy applied?

Answer 18

spec: restartPolicy: OnFailure

Question 19

What are different types of restart policy?

Answer 19

• Always
• Never
• OnFailure

Question 20

What is the apiVersion of a Job?

Answer 20

batch/v1

Question 21

What is the imperative command to get a list of jobs

Answer 21

kubectl get jobs

Question 22

How do you retrieve the output of a job? (e.g. for a job named job1)

Answer 22

kubectl logs job1

Question 23

In the Job definition, how are multiple pods run? (e.g. run the pod 3 times successfully)

Answer 23

spec: completions: 3

Question 24

In the Job definition, how can jobs be run in parallel? (e.g. run 3 pods in parallel)

Answer 24

spec: parallelism: 3

Question 25

What is the purpose of a CronJob?

Answer 25

A CronJob creates Jobs on a repeating schedule.

Question 26

What is the apiVersion of a CronJob?

Answer 26

batch/v1beta

Question 27

What are the two required spec properties of a CronJob?

Answer 27

spec: schedule: "" jobTemplate: {}

Question 28

What are the five properties of the CronJob schedule (in order)?

Answer 28

• minute (0 - 59)
• hour (0 - 23)
• day of the month (1 - 31)
• month (1 - 12)
• day of the week (0 - 6). Sunday to Saturday

Question 29

What is the imperative command to list all the CronJobs?

Answer 29

kubectl get cronjobs