Config - ConfigMaps

Question 1

1.

What are ConfigMaps used for?

Answer 1

• to pass configuration data in the form of key-value pairs in kubernetes
• when a pod is created, inject the config data into the pod, so that the key-value pairs available as environment variables for the hosted application in the pod

Question 2

Which phases are involved in working with ConfigMaps?

Answer 2

• create the configMap
• Inject into the pod

Question 3

How do you create configMaps?

Answer 3

Imperative ‘kubectl create configmap …’
Adding the key-value pairs as arguments

‘kubectl create configmap
< config-name> –from-literal=< key>=< value>’

‘kubectl create configmap app-config –from-literal=APP_COLOR=blue’

Question 4

How do you create a config-map from a file?

Answer 4

‘kubectl create config-map app-config –from-file=app_config.properties’

Question 5

What is the decision where to create a configMap from based on?

Answer 5

• based on the amount of properties to be configured
• many properties are easier from a file

Question 6

How does a declarative configMap look?

Answer 6

Yaml file

apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  APP_COLOR: blue
	APP_MODE: prod

Question 7

How can you view a config map?

Answer 7

kubectl get configmaps

kubectl describe configmaps

Question 8

How do you use ConfigMaps in pods?

Answer 8

in Yaml

spec:
 containers:
   - name:
    image:
		ports:
		  - containerPort: 8080
		 envFrom:
		   - configMapRef:
			     name: app-config

Question 9

What options exist in regards to defining config maps in pods?

Answer 9

1. As a single env:
   ~~~
   env:
   - name: APP_COLOR
   valueFrom:
   configMapKeyRef:
   name: app-config
   key: APP_COLOR
   ~~~
2. whole env:
   ~~~
   envFrom:
   - configMapRef:
   name: app-config
   ~~~
3. As data in a file / Volume:
   ~~~
   volumes:
   - name: app-config-volume
   configMap:
   name: app-config
   ~~~

Question 10

Wie wird configmap abgekürzt?

Answer 10

cm