Container Images and Practical

Posted by Manish Panchmatia on Sunday, October 18, 2020 Labels: , / Comments: (0)

Let me share few useful container images to play around with K8s

1. katacoda/docker-http-server
2. k8s.gcr.io/echoserver:1.10
3. nginx
4. busybox
- command: 
  - tail
  - -f
  - /dev/null
5. mendhak/http-https-echo
6.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: echoserver
spec:
  replicas: 3
  selector:
    matchLabels:
      app: echoserver
  template:
    metadata:
      labels:
        app: echoserver
    spec:
      containers:
      - image: gcr.io/google_containers/echoserver:1.0
        imagePullPolicy: Always
        name: echoserver
        ports:
        - containerPort: 8080
---
apiVersion: v1
kind: Service
metadata:
  name: echoserver
spec:
  ports:
  - port: 80
    targetPort: 8080
    protocol: TCP
  selector:
    app: echoserver
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: echoserver
  annotations:
    kubernetes.io/ingress.class: "nginx"
spec:
  rules:
  - host: echo.example.com
    http:
      paths:
      - path: /
        backend:
          serviceName: echoserver
          servicePort: 80
---
7. curl
apiVersion: apps/v1 
kind: Deployment
metadata:
  name: client
  namespace: cli
spec:
  selector:
    matchLabels:
      app: cli
  replicas: 1
  template:
    metadata:
      labels:
        app: cli
    spec:
      containers:
      - name: client
        image: curlimages/curl:latest
        env:
        - name: ADDRESS
          value: "service_name.svc.cluster.local"
        command: [ "/bin/sh", "-c", "while true; do date; curl $ADDRESS 2>/dev/null | grep '<title>'; sleep 0.5; done;" ]

8. kubectl run -it --rm test --image=curlimages/curl --restart=Never -- /bin/sh

9. Docker Image: us-docker.pkg.dev/google-samples/containers/gke/hello-app:2.0

K8s microservice: kubectl expose deploy hw11 --port=80 --target-port=8080 --dry-run=client -o yaml

Script : please run in pod as per 8 above. 

while true; 
do curl n2iwf;
sleep 1; 
done

10. Echo server: hashicorp/http-echo:0.2.3 Port 5678

Here are example Dockerfiles

Here are few posts about hands on with K8s


CKA and CKAD: My Notes and Website Links

Posted by Manish Panchmatia Labels: , , , / Comments: (0)

Let me post all links, for CKA and CKAD exam

I posted series of articles at my blog: http://layers7.blogspot.com/ as my study note: 

CKAD 

Imperative commands with kubectl http://layers7.blogspot.com/2020/06/imperative-commands-with-kubectl.html

CKA

CKA Tips http://layers7.blogspot.com/2020/10/cka-tips.html
CKA 14: JSON http://layers7.blogspot.com/2020/08/cka-14-json.html
CKA 13: Troubleshooting http://layers7.blogspot.com/2020/08/cka-13-troubleshooting.html
CKA 10: Install K8s the Hard Way http://layers7.blogspot.com/2020/08/cka-10-install-k8s-hard-way.html
Kelseyhightower Kubernetes hard way http://layers7.blogspot.com/2020/05/kelseyhightower-kubernetes-hard-way.html
CKA 9: Networking http://layers7.blogspot.com/2020/08/cka-9-networking.html
CKA 8: Storage http://layers7.blogspot.com/2020/08/cka-8-storage.html
K8s API : http://layers7.blogspot.com/2020/08/k8s-api.html
CKA 7: Security http://layers7.blogspot.com/2020/08/cka-7-security.html
CKA 6: Cluster Maintenance http://layers7.blogspot.com/2020/08/cka-6-cluster-maintenance.html
CKA 5: Application Life Cycle Management http://layers7.blogspot.com/2020/08/cka-5-application-life-cycle-management.html
CKA 4: Logging and Monitoring http://layers7.blogspot.com/2020/07/cka-4-logging-and-monitoring.html
CKA 3: Scheduling http://layers7.blogspot.com/2020/07/cka-scheduling.html
Tmux : http://layers7.blogspot.com/2020/06/tmux.html
RBAC in K8s : http://layers7.blogspot.com/2020/06/rbac-in-k8s.html
CKA 2: K8s Core Concepts http://layers7.blogspot.com/2020/06/cka-k8s-core-concepts.html

To know more about K8s from my blog

Apart form there are many links material on Internet. Here is the list of website, that I am aware about

https://github.com/StenlyTU/K8s-training-official

https://www.shrlrn.com/

https://www.manning.com/books/kubernetes-in-action#toc

https://amartus.com/amartus-kubernetes-exam-tips/

https://devopscube.com/kubernetes-certification-tips/

CKAD
https://itnext.io/the-kubernetes-workloads-3bcf99168c05
https://itnext.io/introduction-to-stateful-services-kubernetes-6018fd99338d
https://itnext.io/learn-how-to-configure-your-kubernetes-apps-using-the-configmap-object-d8f30f99abeb

https://github.com/kelseyhightower/kubernetes-the-hard-way around 10 hrs
https://azure.microsoft.com/en-in/resources/kubernetes-up-and-running/
https://kubernetes.io/
https://discuss.kubernetes.io/
https://kubernetes.io/training/
https://training.linuxfoundation.org/training/kubernetes-for-developers/#outline
https://www.edx.org/course/introduction-to-kubernetes
https://www.edx.org/course/introduction-to-linux
https://killer.sh/course/preview/e84d0e31-4fff-4c42-8afd-be1bdbc0d994
https://github.com/dgkanatsios/CKAD-exercises/blob/master/a.core_concepts.md
https://kubernetes.io/docs/reference/kubectl/cheatsheet/
https://learnk8s.io/troubleshooting-deployments
https://learnk8s.io/academy
https://kodekloud.com/
https://kubernauts.de/en/training/kubernetes-training-course.html
https://docs.google.com/presentation/d/13EQKZSQDounPC1I6EC4PmqaRmdCrpT3qswQJz9KRCyE/edit#slide=id.g33599df588_13_58  It has many excerises
https://collabnix.github.io/kubelabs/
https://www.katacoda.com/courses/kubernetes/playground
https://www.youtube.com/watch?v=c63qr8EFVWE
https://docs.google.com/spreadsheets/d/10NltoF_6y3mBwUzQ4bcQLQfCE1BWSgUDcJXy-Qp2JEU/edit#gid=0
https://killer.sh/
https://github.com/ShubhamTatvamasi/kubernetes-practice-tests
https://github.com/suchakra012/kubernetes-practice-tests

CKA Tips

Posted by Manish Panchmatia on Sunday, October 11, 2020 Labels: , , / Comments: (0)

 * Network Policy: 

- If we put podSelector: {} then it means all pods

- if we do not mention about podSelector at all, then it means none of the pod. 

* We can set env, sa, image, selector, and resources (Requests and Limit)  with kubectl set command

* We can set subject (user | sa | group) for rolebinding | clusterrolebinding

* now (k8s 1.18) kubectl run is only for pod. Not for deployment and job

* We cannot create pv, pvc , .... cannot be with kubectl create

* With 'kubectl expose' command we cannot specify nodePort value. With kubectl create service we can. 

* with 'kubectl create deploy' we can specify replica. Not containerPort

* kubectl auth can-i VERB_ACTION RESOURCE_OBJECT --as USER --namespace NS

* kubectl explain K8s_OBJECT is useful. kubectl explain K8s_OBJECT --recursive is more useful

* kubectl api-resources is useful to know short form

* grep -A N , grep -B N, grep -C N: Here N is number of line. A means after, B is before 

* to run on specific node : nodeName

* mount secret : secretName ; mount configMap : name at Volumes section

* securityContext.capabilities is only for container, not for pod

* useful command: kubectl config set-context --current --namespace=default

* verify taint with kubectl describe node | grep -i Taint

* If we edit replicaset, it impacts when new pod is created. 

* If replicaset is part of deployment and if we delete replicaset, it will be recreate with same name. 

* If pod is part of replicaset and if we delete pod, it will be created with different name. 

* Replicaset has name. Pod has genearateName