Practice on KodeKloud

Some Courses on KodeKloud

coupons in secret.txt

Pod

  • Create a new pod with the nginx image:

kubectl run nginx --image=nginx

  • How many pods are created now?

kubectl get pod

  • What is the image used to create A pod?

kubectl describe pod A | grep -i image

  • Which nodes are these pods placed on?

kubectl describe pod newpods-vkbm2 | grep -i node

kubectl get pod -o wide

  • Delete the webapp Pod.

kubectl delete pod webapp

  • Create a new pod with the name redis and the image redis123.

kubectl run redis --image=redis123

ReplicaSets

  • How many ReplicaSets exist on the system?

kubectl get replicaset --no-headers | wc -l

  • What is the image used to create the pods in the new-replica-set?

kubectl describe replicaset | grep -i image

  • Create a ReplicaSet using the replicaset-definition-1.yaml

  • You can check for apiVersion of replicaset by command

kubectl api-resources | grep replicaset

controlplane ~ ➜  cat replicaset-definition-1.yaml 
apiVersion:apps/v1
kind: ReplicaSet
metadata:
  name: replicaset-1
spec:
  replicas: 2
  selector:
    matchLabels:
      tier: frontend
  template:
    metadata:
      labels:
        tier: frontend
    spec:
      containers:
      - name: nginx
        image: nginx

controlplane ~ ➜  kubectl apply -f replicaset-definition-1.yaml 
replicaset.apps/replicaset-1 created
  • Delete the ReplicaSets:

kubectl delete replicaset replicaset-name

kubectl delete -f file-name.yaml

  • Fix the original replica set new-replica-set to use the correct busybox image.

    • Modify the image name and then save the file.

      kubectl edit replicaset new-replica-set

    • Then, delete the previous pods to get the new ones with the correct image.

  • Scale the ReplicaSet to 5 PODs.

    • Modify the replicas and then save the file

      kubectl edit replicaset new-replica-set

    • Or:

      kubectl scale rs new-replica-set --replicas=5

Label & Selector

  • How many PODs exist in the dev environment (env)?

kubectl get pod --selector env=dev --all-namespaces

kubectl get pod --selector env=dev --all-namespaces --no-headers | wc -l

  • How many objects are in the prod environment including PODs, ReplicaSets and any other objects?

kubectl get all --selector env=prod --all-namespaces --no-headers | wc -l

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

kubectl get pod --selector env=prod,bu=finance,tier=frontend --all-namespaces

Namespace

  • How many Namespaces exist on the system? namespace === ns

kubectl get namespaces --no-headers | wc -l

  • How many pods exist in the research namespace?

kubectl get pod -n research --no-headers | wc -l

  • Create a POD in the finance namespace.

kubectl run redis --image=redis -n finance

  • Which namespace has the blue pod in it?

kubectl get all --all-namespaces | grep pod | grep blue

  • What DNS name should the Blue application use to access the database db-service in the dev namespace?khác namespace.
controlplane ~ ➜  kubectl get pod --all-namespaces | grep blue
marketing       blue                                      1/1     Running            0             6m44s

controlplane ~ ➜  kubectl get all --all-namespaces | grep db-service
marketing       service/db-service        NodePort       10.43.217.112   <none>         6379:32186/TCP               7m
dev             service/db-service        ClusterIP      10.43.216.191   <none>         6379/TCP                     7m
  • Ta dùng 1 trong 2 domain sau:
    • db-service.dev.svc.cluster.local
    • db-service.dev

Deployment

  • How many Deployments exist on the system?

kubectl get deployment

Configmap

  • What is the environment variable name set on the container in the pod?

kubectl get pod webapp-color -o yaml

kubectl describe pod webapp-color

  • Update the environment variable on the POD to display a green background. Khi pod đang running thì không thể edit để thay đổi các thông tin như env variable,... chỉ có thể thay đổi image

    • Ta sẽ tiến hành ghi cái file config sang file mới và edit thông tin mong muốn

      kubectl get pod webapp-color -o yaml > webapp.yaml

    • Sau đó xóa pod cũ => apply file yaml mới

      kubectl apply -f webapp.yaml

  • How many ConfigMaps exists in the default namespace?

kubectl get configmaps

  • Identify the database host from the config map db-config.

kubectl describe configmaps db-config

kubectl get configmaps db-config -o yaml

  • Create a new ConfigMap for the webapp-color POD. Use the spec given below.
    • ConfigMap Name: webapp-config-map
    • Data: APP_COLOR=darkblue
    • Data: APP_OTHER=disregard

kubectl create configmap webapp-config-map --from-literal=APP_COLOR=darkblue --from-literal=APP_OTHER=disregard

apiVersion: v1
kind: ConfigMap
metadata:
  name: webapp-config-map
data:
  APP_COLOR: darkblue
  APP_OTHER: disregard
  • Convert from non configmap => configmap
- env:
    - name: APP_COLOR
      value: green

- env:
    - name: APP_COLOR
      valueFrom:
        configMapKeyRef: 
          name: webapp-config-map
          key: APP_COLOR

Secrets

  • How many Secrets exist on the system?

kubectl get secrets

  • How many secrets are defined in the dashboard-token secret?

kubectl get secrets dashboard-token -o yaml

  • Create a new secret named db-secret with the data given below.
    • Secret Name: db-secret
    • Secret 1: DB_Host=sql01
    • Secret 2: DB_User=root
    • Secret 3: DB_Password=password123

Method 1:

kubectl create secret generic db-secret --from-literal=DB_Host=sql01 --from-literal=DB_User=root --from-literal=DB_Password=password123

Method 2:

apiVersion: v1
kind: Secret
metadata:
  name: db-secret
type: opaque
stringData: # k8s auto encode data để lưu trữ trong secret mà không cần encode Base64 trước.
  DB_Host: sql01
  DB_User: root
  DB_Password: password123

Method 3:

apiVersion: v1
kind: Secret
metadata:
  name: db-secret
type: opaque
data: 
  DB_Host: # encode Base64
  DB_User: # encode Base64
  DB_Password: # encode Base64
  • Configure webapp-pod to load environment variables from the newly created secret.
spec:
  containers:
  - image: kodekloud/simple-webapp-mysql
    imagePullPolicy: Always
    name: webapp
    envFrom: # add
    - secretRef: # add
        name: db-secret # add

Ingress

  • Let us now deploy an Ingress Controller.

    • First, create a namespace called ingress-nginx.

    kubectl create namespace ingress-nginx

    • The NGINX Ingress Controller requires a ConfigMap object. Create a ConfigMap object with name ingress-nginx-controller in the ingress-nginx namespace.

    kubectl create configmap ingress-nginx-controller --namespace ingress-nginx

    • The NGINX Ingress Controller requires two ServiceAccounts. Create both ServiceAccount with name ingress-nginx and ingress-nginx-admission in the ingress-nginx namespace.

    kubectl create serviceaccount ingress-nginx --namespace ingress-nginx

    kubectl create serviceaccount ingress-nginx-admission --namespace ingress-nginx

    • Create the ingress resource to make the applications available at /wear and /watch on the Ingress service. Also, make use of rewrite-target annotation field: nginx.ingress.kubernetes.io/rewrite-target: /
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ingress-wear-watch
  namespace: app-space
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
    nginx.ingress.kubernetes.io/ssl-redirect: "false"
spec:
  rules:
  - http:
      paths:
      - path: /wear
        pathType: Prefix
        backend:
          service:
           name: wear-service
           port: 
            number: 8080
      - path: /watch
        pathType: Prefix
        backend:
          service:
           name: video-service
           port:
            number: 8080

Ví dụ: Nếu Ingress có nginx.ingress.kubernetes.io/rewrite-target: /app, mọi yêu cầu đến /wear sẽ được rewrite thành /app/wear trước khi được chuyển đến service wear-service.