Scheduling - Labels and Selectors

Q) We have deployed a number of PODs. They are labelled with tier, env and bu. How many PODs exist in the dev enviroment (env)?

$ k get po --selector='env=dev' -A --no-headers | wc -l
7

A) 7

 

Q) How many PODs are in the finance business unit (bu)?

$ k get po -A --selector bu=finance --no-headers | wc -l
6

A) 6

 

Q) How many objects are on prod environment? (including all kubernetes objects such as replicasets, deployments, etc.)

$ k get all -A --selector env=prod --no-headers | wc -l
7

A) 7

 

Q) Identify the POD which is part of the prod environment, the finance BU and of frontend tier?

$ k get po -A -l env=prod,bu=finance,tier=frontend
NAMESPACE   NAME          READY   STATUS    RESTARTS   AGE
default     app-1-zzxdf   1/1     Running   0          7m26s

A) app-1-zzxdf

 

Q) A ReplicaSet definition file is given replicaset-definition-1.yaml. Attempt to create the replicaset; you will encounter an issue with the file. Try to fix it.

$ k apply -f replicaset-definition-1.yaml 
The ReplicaSet "replicaset-1" is invalid: spec.template.metadata.labels: Invalid value: map[string]string{"tier":"nginx"}: `selector` does not match template `labels`

$ vi replicaset-definition-1.yaml

apiVersion: apps/v1
kind: ReplicaSet
metadata:
   name: replicaset-1
spec:
   replicas: 2
   selector:
      matchLabels:
        tier: front-end
   template:
     metadata:
       labels:
        # tier: nginx
        # template must match the selector > matchLabels
        tier: front-end
     spec:
       containers:
       - name: nginx
         image: nginx

$ k apply -f replicaset-definition-1.yaml 
replicaset.apps/replicaset-1 created