YAML in Kubernetes

Question 1

4 top level fields

Answer 1

apiVersion:

kind:

metadata:

spec:

[all required]

Question 2

apiVersion

Answer 2

POD, Service: v1

ReplicaSet, Deployment: apps/v1

Question 3

kind

Answer 3

POD, Service, ReplicaSet, Deployment

Question 4

metadata

Answer 4

a dictionary form, data about the object

metadata expected by kubernetes

labels - do as you wish

metadata:

name: my-app-pod

labels:

app: my-app
type: front-end

Question 6

spec

Answer 6

different for different objects

soec:

containers:

• name: nginx-container
  image: nginx

Question 7

cmd for creating a pod form pod.yml

Answer 7

kubectl create -f pod.yml

Question 8

cmd list pods

Answer 8

kubectl get pods

Question 9

cmd show info about my-pod

Answer 9

kubectl describe pod my-pod

Question 10

yaml for postgress

Answer 10

apiVersion: v1
kind: Pod
metadata:
name: postgres
labels:
tier: db-tier
spec:
containers:
- name: postgres
image: postgres
env:
- name: POSTGRES_PASSWORD
value: mysecretpassword

Question 11

create pod my-nginx and look at it

Answer 11

kubectl run my-nginx –image=nginx

kubectl get pods

kubectl get pods -o wide

kubectl describe pod my-nginx

Question 12

Controllers

Answer 12

Processes that monitor kubernetes objects and respond accordingly. Control loops that watch the state of your cluster, then make or request changes where needed

Question 13

Replication Controller

Answer 13

It ensures that a specified number of pods run at all times.

Load balancing and scaling

Question 14

Replication Controller vs Replica Set

Answer 14

Older vs newer, recommended technology.

RS can be used to monitor the existing pods.

Question 15

rc-definition.yml

Answer 15

apiVersion:

kind:

metadata:

spec:

template:

pod-definition.yml - (apiVersion+kind)

replicas:

Question 16

create replication controller from my-rc.yaml

list replication controllers

list pods created

Answer 16

kubectl create -f my-rc.yaml

it creates x replicas based on a template

kubectl get replicationcontroller

kubectl get pods

rc-name..

rc-name..

rc-name..

Question 17

rs-definition.yaml

Answer 17

apiVersion: apps/v1

kind: ReplicaSet

metadata:

spec:

template:

replicas:

selector:

Question 18

selector rc vs rs

Answer 18

optional, takes labels / must have

selector:

matchLabels:

Question 19

How replica set knows what pods to monitor?

Answer 19

Labels used while creating a pod can be used as a filter

selector:

matchLabels:

key: value

Question 20

In replica set, do we need a templete if e.g. we create the rs to monitore existing pods?

Answer 20

Yes, in case one of them fails, rs will have a template to create a new one.

Question 21

Ho to scale pods definded in replica set.

Answer 21

1. Update replicas in file and:

kubectl replace -f rs-definition.yaml

2. kubectl scale –replicas=6 -f rs-definition
3. kubectl scale –replicas=6 replicaset <kind> <metadata.name> [won't update the rs.yaml]</metadata.name></kind>
4. scale based on load

Question 22

ReplicaSet spec’s 3 fields

Answer 22

spec:

template:

replicas:

selector:

Question 23

ReplicaSet template example

Answer 23

template:

metadata:
name: myapp-pod
labels:
app: myapp
spec:
containers:
- name: nginx
image: nginx

Question 24

ReplicaSet selector example

Answer 24

selector:
labels:
app: myapp

Question 25

modify definition for new-replica-set

Answer 25

kubectl edit replicaset new-replica-set

Question 26

update instances one aftr another

Answer 26

rolling updates

Question 27

What is a deployment?

Answer 27

Upgrade underlying instances seamlesly, usuing roling updates.

Question 28

create a deployment from my-deployment.yaml

list deployments

list replicaset

list pods

Answer 28

file as replica set, except for

kind: Deployment

kubectl create -f my-deployment.yaml

kubectl get deployments

kubectl get replicaset

(my-deployment-2424)

kubectl get pods

(my-deployment-37584)