/kubernetes-exercises

Forget it. Its not for you. Just some kubernetes configuration exercises.

kubernetes-exercises

Forget it. Its not for you. Just some kubernetes configuration exercises.

Kubernetes shortcuts:

  • po : PODS
  • rs: replicasets
  • deploy: deployments
  • svc : services
  • ns : namespaces
  • netpol: network policies
  • pv: persistent volumes
  • pvc: persistent volume claims
  • sa : service accounts

general cmds

List PODs:

$ kubectl get pods

Show POD info:

$ kubectl describe pod <POD NAME>

Stop a POD:

$ kubectl stop pod nginx-7cdbd8cdc9-wzht9

Run a POD from a docker image

$ kubectl run nginx --image nginx

Service NodePort:

Create from yaml

$ kubectl create -f service-nodeport-definition.yaml

List services

$ kubectl get services

Service Cluster IP:

Create from yaml

$ kubectl create -f service-clusterip-definition.yaml

List services

$ kubectl get services

pod-configuration.yml:

Create from yaml

$ kubectl create -f pod-definition.yml

Update POD using yaml:

# kubectl apply -f pod-definition.yml

[cron]job-definition.yml

Create from yaml

$ kubectl create -f [cron]job-definition.yml

Update POD using yaml:

# kubectl apply -f [cron]job-definition.yml

rc-definition.yml:

Create from yaml

$ kubectl create -f rc-definition.yml

Update replication controller using yaml:

# kubectl replace -f rc-definition.yml

List replication controllers

$ kubectl get replicationcontroller

replicaset-definition.yml:

Create from yaml

$ kubectl create -f replicaset-definition.yml

Update replica set using yaml:

# kubectl replace -f replicaset-definition.yml

Delete:

# kubectl delete replicaset myapp-replicaset

Edit:

# kubectl edit replicaset myapp-replicaset

List replica set

$ kubectl get replicaset

To scale:

$ kubectl scale --replicas=6 -f replicaset-definition.yml

or using replicaset name: $ kubectl scale --replicas=6 replicaset myapp-replicaset

deployment-definition.yml:

Apply from yaml

$ kubectl apply -f deployment-definition.yml

namespace-definition.yml:

Create dev from yaml

$ kubectl apply -f namespace-definition.yml

Create dev from kubectl:

$ kubectl create namespace dev

Get resources from a specific namespace:

$ kubectl get pods --namespace=dev

Switching permanently to another namespace:

$ kubectl config set-context $(kubectl config current-context) --namespace=dev

Get resources from all namespaces:

$ kubectl get pods --all-namespaces

resource-quota.yml:

Create from yaml

$ kubectl apply -f resource-quota.yml

Others

Dashboard

Install Dashboard:

$ kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/v1.10.1/src/deploy/recommended/kubernetes-dashboard.yaml

Access Dashboard at:

$ kubectl proxy

List Dashboard PODs:

kubectl get secret,sa,role,rolebinding,services,deployments --namespace=kube-system | grep dashboard

Remove all Dashboard PODS at once:

kubectl delete deployment kubernetes-dashboard --namespace=kube-system 
kubectl delete service kubernetes-dashboard  --namespace=kube-system 
kubectl delete role kubernetes-dashboard-minimal --namespace=kube-system 
kubectl delete rolebinding kubernetes-dashboard-minimal --namespace=kube-system
kubectl delete sa kubernetes-dashboard --namespace=kube-system 
kubectl delete secret kubernetes-dashboard-certs --namespace=kube-system
kubectl delete secret kubernetes-dashboard-key-holder --namespace=kube-system

To Authenticate Using Token

Create a new ServiceAccount

kubectl create serviceaccount k8sadmin -n kube-system

Create a ClusterRoleBinding with Cluster Admin Privileges

kubectl create clusterrolebinding k8sadmin --clusterrole=cluster-admin --serviceaccount=kube-system:k8sadmin

Then you should Generate a token:

$ kubectl get secret -n kube-system | grep k8sadmin | cut -d " " -f1 | xargs -n 1 | xargs kubectl get secret  -o 'jsonpath={.data.token}' -n kube-system | base64 --decode

Now you can access it via http://localhost:8001/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy/ , then select authenticate via TOKEN and paste the generated Token in the previous step.

Others

To set a specific image:

$ kubectl set image deployment/my-deployment some-image=new-image:1.2

Deployment status:

$ kubectl rollout status deployment/myapp-deployment

Deployment History

$ kubectl rollout history deployment/myapp-deployment

Deployment Undo

$ kubectl rollout undo deployment/myapp-deployment

Discovering deployment type:

$ kubectl describe deployment

Deployment types:

  • recreate: terminate the old version and release the new one
  • ramped: release a new version on a rolling update fashion, one after the other
  • blue/green: release a new version alongside the old version then switch traffic
  • canary: release a new version to a subset of users, then proceed to a full rollout
  • a/b testing: release a new version to a subset of users in a precise way (HTTP headers, cookie, weight, etc.). A/B testing is really a technique for making business decisions based on statistics but we will briefly describe the process. This doesn’t come out of the box with Kubernetes, it implies extra work to setup a more advanced infrastructure (Istio, Linkerd, Traefik, custom nginx/haproxy, etc).

Restart Policy

Possible values Always, OnFailure, and Never. The default value is Always.

Ingress

Controller

Using NGINX as ingress controller:

  • Deployment: nginx-ingress-controller.yaml
  • Service: nginx-nodeport-service.yaml
  • ConfigMap: nginx-configuration.yaml
  • Auth: nginx-serviceaccount.yaml

Resource

Example for a demo app called myapp : ingress-sample-resource-to-myapp.yaml. Another exeample using paths is located at ingress-sample-resource-to-myapp-with-rules.yaml.

To get all ingress services:

$ kubectl describe ingress ingress-myapp

Network Policy

ingress-networkpolicy.yaml

Volumes:

To list volumes:

$ kubelctl get volume
$ kubelctl get persistentvolume

To list claims:

$ kubectl get persistentvolumeclaim
  • efemeral: volumes.yml
  • persistent: persistent-volume.yml
  • persistent claims: persistent-volume-claim.yml