Kubernetes

#Current shell

source <(kubeadm completion bash)

source <(kubectl completion bash)

#Allows scheduling on the master

kubectl taint nodes --all node-role.kubernetes.io/master-

#Kubeadm

sudo dnf update kubeadm

sudo kubeadm upgrade plan

sudo kubeadm upgrade apply v1.14.1

sudo dnf update kubelet

sudo systemctl restart kubelet

https://kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade-1-14/

#Base

kubectl get nodes -o wide

kubectl get pods --all-namespaces -o wide

kubectl get deployments --all-namespaces -o wide

kubectl get services --all-namespaces -o wide

kubectl get service sleep -o json

kubectl get endpoints sleep

kubectl describe pod [-n kube-system]

kubectl describe service [-n kube-system]

kubectl apply -f /etc/kubernetes/manifests/sleep.yml

kubectl describe pod sleep-7674d45776-9rn2p -n default

kubectl exec -it sleep-7674d45776-9rn2p /bin/bash

kubectl delete service sleep

kubectl delete deployment sleep

kubectl run [--namespace=policy-demo] nginx --replicas=3 --image=nginx

kubectl expose [--namespace=policy-demo] deployment nginx --port=80 [--type=NodePort]

kubectl proxy??

kubectl port-forward $POD_NAME <local_port>:<pod_port>??

kubectl describe deployment nginx

kubectl edit deployment nginx

kubectl scale [--current-replicas=3] --replicas=2 deployment nginx

kubectl run hostnames --image=k8s.gcr.io/serve_hostname --labels=app=hostnames --port=9376 --replicas=3

#ServiceAccount

kubectl get sa --all-namespaces

#Pod

kubectl run -i --tty --rm debug --restart=Never --image=alpine -- wget -qO - 10.0.2.17:80

kubectl run -ti --rm debug --restart=Never --image busybox /bin/sh

kubectl run -i --tty --rm debug --restart=Never [--namespace=policy-demo] --image=centos -- /bin/bash

#Node

kubectl taint nodes <node_name> key=value:NoSchedule[-]

kubectl taint nodes <node_name> key=value:NoExecute

sudo docker ps | sudo crictl ps

sudo docker inspect --format '{{ .State.Pid }}' container-id-or-name | sudo crictl inspect -o json container-id-or-name | jq .info.pid

nsenter -t your-container-pid -n ip addr

nsenter -t your-container-pid -n ngrep -W byline -td any . port 53

sudo conntrack -L -d 10.96.0.10

sudo iptables -vL | grep DROP | watch -d sudo iptables -L -v -n

#Net

kubectl get po --all-namespaces -o json | jq .items[].status.podIP -r | egrep '^10' | fping

kubectl -n kube-system get configmap calico-config -oyaml

#DNS

kubectl describe services -n kube-system kube-dns

kubectl get endpoints -l k8s-app=kube-dns --all-namespaces -o json

kubectl describe pod --namespace=kube-system [coredns-86c58d9df4-6csb4]

for p in $(kubectl get pods --namespace=kube-system -l k8s-app=kube-dns -o name); do kubectl logs --namespace=kube-system $p; done

kubectl -n kube-system get configmap coredns -oyaml

kubectl -n kube-system edit configmap coredns

kubeadm upgrade apply v1.11.0 --feature-gates=CoreDNS=true

nslookup kubernetes.default.svc.cluster.local

nslookup kubernetes-dashboard.kube-system.svc.cluster.local

#Dashboard

https://github.com/kubernetes/dashboard/wiki/Creating-sample-user

https://kubernetes.io/docs/tasks/access-application-cluster/web-ui-dashboard/

https://github.com/kubernetes/dashboard/wiki/Accessing-Dashboard---1.7.X-and-above

kubectl -n kube-system describe secret $(kubectl -n kube-system get secret | grep kubernetes-dashboard-token | awk '{print $1}')

kubectl get secret $(kubectl get serviceaccount dashboard -o jsonpath="{.secrets[0].name}") -o jsonpath="{.data.token}" | base64 --decode

#MariaDB

kubectl get secret mariadb -ojsonpath="{.data.mariadb-root-password}" | base64 --decode

#Kube Proxy

http://localhost:8001/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:https/proxy/

http://localhost:8001/api/v1/namespaces/default/services/http:phpmyadmin:http/proxy/

watch -d 'kubectl get deployments --all-namespaces -o wide; echo ' ';kubectl get services --all-namespaces -o wide;echo ' ';kubectl get pods --all-namespaces -o wide;echo ' ';sudo iptables -L'

#Reference

https://kubernetes.io/docs/reference/kubectl/cheatsheet/