kubectl commands

kubectl-commands.md

filter kubernetes response with kubectl

make file with all results , then filter into new file

kubectl get nodes > all_nodes.txt

cat all_nodes.txt | while read line ; do if [[ $line == *"sobusy"* ]]; then echo $line; fi; done > filtered_nodes.txt

filter results by search criteria

kubectl logs <pod> <search_criteria> > some_file.txt

ex kubectl logs busybox | grep fail > logs.txt

see processes running

ps aux

kubectl commands

kubectl cluster-info - get cluster info

create

kubectl create namespace [namespace] - create a namespace

kubectl create -f [yaml file] --namespace [nmamespace] - create a pod in a specific namespace using yaml file

config

kubectl config get-contexts - get contexts

kubectl config use-context [context name] - use different context

get / describe

kubectl get componentstatus - status of all components

kubectl get pods -n testing [pod name] -o jsonpath={.spec.containers[*].name} - get container names from a pod

kubectl get --watch pod [pod name] -n testing - watch for changes to a pod

kubectl get events - get events on the cluster (events are namespaced)

kubectl get pods -l person=kevin - get resources by label

kubectl get node <node> -o wide - get more info from resource

kubectl get pods --show-labels - show all labels

kubectl describe pod -n testing [pod name] - describe pod

logs

kubectl logs -f -n testing [pod name] - get logs from a pod

kubectl logs <pod_name> | grep <search_term> - filter logs from a pod

kubectl logs -f -n testing [pod name] -c [container name] - get logs from a container

usage

kubectl top pods - get usage info for pods

kubectl top pod [pod name] --containers -n prod - get usage info for containers in a pod

kubectl top node [node name] - get top info for a node

kubectl top pod --namespace=C --selector=A=B

scale

kubectl scale rc production --replicas=6

secrets

create a secret and update it if it does not exist yet

kubectl create secret generic kevin-secret --from-file=my_secret.txt --dry-run -o yaml | kubectl apply -f -

kubectl create secret generic my-secret --from-literal=key1=supersecret - secret from literal

setup simple kubernetes pod with an ubuntu container, expose port 8080 on the node

kubectl run my_nginx --image=nginx --replicas=2 --port=80 - make simple deployment with two replicas

kubectl run ubuntu-pod --image=gcr.io/google_containers/ubuntu:14.04 --port=8080

kubectl expose deployment ubuntu-pod --type=NodePort - create service for existing service

rolling update

set an image to a new version on a deployment, which will trigger an update

kubectl set image deployment/nginx-deployment nginx=nginx:1.9.1 --record

kubectl rollout history deployment/nginx-deployment - check history

kubectl rollout status deployment nginx-deployment - check rollout status

kubectl label pods --all person=kevin - attach label to resource

kubectl label pods --all person- - remove label from resource

drain

kubectl drain $node --delete-local-data=true --force (add & to throw into the background)

dns lookup

run nginx pods via deployment

$ kubectl run nginx-is-dumb --image=nginx --replicas=2 --port=80
deployment "nginx-is-dumb" created

back them by a service

$ kubectl expose deployment nginx-is-dumb
service "nginx-is-dumb" exposed

$ kubectl run busybox --image=busybox --rm --restart=OnFailure -ti -- /bin/nslookup nginx-is-dumb.default
Server:    10.11.240.10
Address 1: 10.11.240.10 kube-dns.kube-system.svc.cluster.local

In order to get the pod’s IP address, look up the ip for the pod by running kubectl describe pod nginx-is-dumb, and then, inside the busybox temp pod, run:

kubectl run busybox --image=busybox --rm --restart=OnFailure -ti -- /bin/nslookup <pod-ip>.default.pod.cluster.local

which will give you four lines of output. We want the bottom two lines.

other dns lookup

create nginx pod and expose it k run -it --rm --restart=Never --image=infoblox/dnstools:latest dnstools

nslookup nginx.default.svc.cluster.local

etcd backup

sudo chown -R student:student /opt

ssh onto etcd node

sudo su -

cat /proc/$(pgrep etcd)/environ | xargs -0 -n1 echo | grep ETCD_DATA

that will give you the data directory

etcdctl backup --data-dir <data directory> --backup-dir <target dir>

bring components onto node

ssh onto the node you want to setup

scp hk8s-node-1:/etc/systemd/system/kubelet.service .
scp hk8s-node-1:/etc/systemd/system/kube-proxy.service .
scp kubelet.service ik8s-node-0:
scp kube-proxy.service ik8s-node-0:
ssh ik8s-node-0 

manually edit over there, put into /etc/systemd/system, use systemctl, etc.

have kubelet bring up a resource

• ssh onto worker node
• sudo su -
• Edit /etc/systemd/system/kubelet.service
• Add --pod-manifest-path /etc/kubernetes/manifests
• mkdir -p /etc/kubernetes/manifests make sure path exists
• Add the pod manifest file (this is the yaml file) to /etc/kubernetes/manifests
• systemcl daemon-reload
• systemctl restart kubelet.service or whatever the kubelet service is called, on juju was sudo systemctl restart snap.kubelet.daemon.service