OpenShift & K8S Cheat Sheet

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1 Kubernetes

1.1 Setup

1.1.1 kubectl-neat

mkdir $HOME/bin ; cd $HOME/bin 
rm -f kubectl-neat
chmod 700 kubectl-neat
tar vxfz kubectl-neat_linux_amd64.tar.gz
rm -f LICENSE kubectl-neat_linux_amd64.tar.gz

1.1.2 kubectl

mkdir $HOME/bin ; cd $HOME/bin 
rm -f kubectl
curl -LO$(curl -s
chmod 700 kubectl
grep 'kubectl completion bash' $HOME/.bashrc || echo 'source <(kubectl completion bash)' >> $HOME/.bashrc

1.1.3 helm

curl | sh
grep 'helm completion bash' $HOME/.bashrc || echo 'source <(helm completion bash)' >> $HOME/.bashrc

1.2 Daily


1.2.1 SHELL

  • Authenticate Kubectl
export KUBECONFIG=<PATH-TO-CONFIG>/kubeconfig-dev.yaml

1.2.2 Use Helm

export KUBECONFIG=/etc/rancher/k3s/k3s.yaml # for K3S
helm search hub wordpress --max-col-width 120
helm repo add stable
helm repo add bitnami
helm repo update

1.2.3 Install APP with Helm

kubectl create namespace wordpress
kubectl config set-context --current --namespace=wordpress
helm install my-wordpress bitnami/wordpress
kubectl get all
kubectl delete service my-wordpress
kubectl get pods
kubectl exec my-wordpress-55dc589b4c-ldkxj -- printenv | grep HTTP
kubectl expose deployment/my-wordpress --port=8080 --name=my-wordpress
kubectl get service
kubectl create ingress ingress-www*=my-wordpress:8080
# User: user
# Password: $(kubectl get secret --namespace wordpress my-wordpress -o jsonpath="{.data.wordpress-password}" | base64 --decode)

helm delete my-wordpress
kubectl delete namespace wordpress

1.2.4 Export current Namespace Objects

for n in $(kubectl get -o=name pvc,configmap,ingress,service,secret,deployment,statefulset,hpa,job,cronjob | grep -v 'secret/default-token')
   kubectl get -o=yaml --export $n > $(dirname $n)_$(basename $n).yaml

1.2.5 Export Objects for all Namespaces

for n in $(kubectl get -o=custom-columns=NAMESPACE:.metadata.namespace,KIND:.kind, pv,pvc,configmap,ingress,service,secret,deployment,statefulset,hpa,job,cronjob,serviceaccount --all-namespaces | grep -v 'secrets/default-token')
    if (( $i < 1 )); then
        if [[ "$namespace" == "PersistentVolume" ]]; then
    elif (( $i < 2 )); then
    elif (( $i < 3 )); then
        if [[ "$namespace" != "NAMESPACE" ]]; then
            mkdir -p $namespace
            yaml=$((kubectl get $kind -o=yaml $name -n $namespace ) 2>/dev/null)
            if [[ $kind != 'Secret' || $yaml != *"type:"* ]]; then
                echo "Saving ${namespace}/${kind}.${name}.yaml"
                kubectl get $kind -o=yaml $name -n $namespace > $namespace/$kind.$name.yaml

1.2.6 Export all Manifests in all Namespaces

while read -r line
    output=$(kubectl get "$line" --all-namespaces -o yaml 2>/dev/null | grep '^items:')
    if ! grep -q "\[\]" <<< $output; then
        echo -e "\n======== "$line" manifests ========\n"
        kubectl get "$line" --all-namespaces -o yaml
done < <(kubectl api-resources | awk '{print $1}' | grep -v '^NAME' | grep -v events | sort -u)

1.2.7 .bash_profile

  • openshift project/user prompt
source <(kubectl completion bash)
export PS1='### \D{%d.%m.%Y_%H:%M} \u@\e[1;32m\h\e[m:\w \e[1;33m✯ $(kubectl config view -o jsonpath="{.contexts[].context.namespace}")\e[m \n# '
  • password gen
genpasswd() {
   local l=$1
   [ "$l" == "" ] && l=16
   tr -dc A-Za-z0-9_=., < /dev/urandom | head -c ${l} | xargs 

1.3 Deploy

1.3.1 Create and change into Namespace

kubectl create namespace mynamespace
kubectl config set-context --current --namespace=mynamespace

1.3.2 Deploy Docker Container and Expose Service

kubectl create deployment xfce --image=christian773/xfce-vnc:latest --port=6901

1.3.3 Inject VARS into Deployment/Container

kubectl edit deployment nginx1
  - name: nginx
    image: nginx:1.7.9
    - name: MY_VAT
      value: MY_VALUE

1.3.4 Get Environment VARS of Pod

kubectl exec pod-name -- printenv

1.3.5 Expose Container Port as Service

kubectl expose deployment nginx-app --port=8080 --name=nginx-service

1.3.6 Create Ingress Rule for Service

kubectl create ingress ingress-www*=nginx-service:8080

1.4 Configure

1.4.1 Traefik Config


kubectl edit deployments traefik -n kube-system
kubectl -n kube-system edit cm traefik

1.5 Debug

1.5.1 Run Container with custom Command

kubectl run -i --tty busybox --image=busybox -- sh

1.5.2 Attach Container in Pod (log)

kubectl attach busybox -c busybox -i -t

1.5.3 Jump into Pods Shell

kubectl exec --stdin --tty shell-demo -- /bin/bash

1.5.4 Get all Containers on all Namespaces

kubectl get pods --all-namespaces -o jsonpath="{..image}" |tr -s 'space:' '\n' |sort |uniq -c

1.5.5 Get all Containers grouped by Pods for all Namespaces

kubectl get pods --all-namespaces -o=jsonpath='{range .items[*]}{"\n"}{}{":\t"}{range .spec.containers[*]}{.image}{", "}{end}{end}' |sort

1.5.6 Open Firewall for NodePort (non persistent)

kubectl describe svc | grep NodePort: | awk '{print $3}' | tr 'A-Z' 'a-z' | grep -v '^$' | while read PORT
  echo PORT=$PORT
  firewall-cmd --zone=public --add-port=$PORT

2 OpenShift

2.1 Install

2.1.1 OC & KUBECTL (OKD)

mkdir $HOME/bin ; cd $HOME/bin 
rm -f oc
wget$(curl -L | grep openshift-client-linux | grep href= | cut -d\" -f2 )
tar vxfz openshift-client-linux-*.tar.gz
rm -rf openshift-client-linux-*.tar.gz
grep 'oc completion bash' $HOME/.bashrc || echo 'source <(oc completion bash)' >> $HOME/.bashrc
grep 'kubectl completion bash' $HOME/.bashrc || echo 'source <(kubectl completion bash)' >> $HOME/.bashrc

2.1.2 OC & KUBECTL (OpenShift)

mkdir $HOME/bin ; cd $HOME/bin 
rm -f oc kubectl
tar vxfz oc.tar.gz 
rm -f oc.tar.gz
grep 'oc completion bash' $HOME/.bashrc || echo 'source <(oc completion bash)' >> $HOME/.bashrc
grep 'kubectl completion bash' $HOME/.bashrc || echo 'source <(kubectl completion bash)' >> $HOME/.bashrc

2.1.3 .bash_profile

  • openshift project/user prompt
function ps1(){
   export PS1='[\u@\h($(oc whoami -c 2>/dev/null|cut -d/ -f3,1)) \W]\$ '
function ps1e(){
   export PS1='# [\d \t \u@\h($(oc whoami -c 2>/dev/null|cut -d/ -f3,1)) \W]\n$ '
  • password gen
genpasswd() {
        local l=$1
        [ "$l" == "" ] && l=16
        tr -dc A-Za-z0-9_=%.,: < /dev/urandom | head -c ${l} | xargs 

3 Administration

3.1 daily cmds

oc get nodes -o wide
oc get all -o wide --all-namespaces
oc get ep -o wide
oc get events --sort-by='.lastTimestamp'
oc get rolebindings --all-namespaces
oc get pv
oc get pvc
oc get projects
oc get users
oc get groups

3.2 inspect user/group permissions

oc get rolebinding -o wide -n gitea
oc get rolebinding -o wide --all-namespaces

3.3 inspect imagestreams

oc get is -n openshift
oc describe is php -n openshift
oc export -n openshift isimage php@42c4a9072f

4 snippets

4.1 run as root (anyuid)

oc create serviceaccount sa-anyuid
oc adm policy add-scc-to-user anyuid -z sa-anyuid
# create new-app before to get a dc
oc patch dc/deployment-config-name --patch '{"spec":{"template":{"spec":{"serviceAccountName": "sa-anyuid"}}}}'

4.2 run as root (anyuid) for every pod in project

oc adm policy add-scc-to-user anyuid -z default

4.3 imagestream demo (build service)

  • get all the imagestreams
oc get is -n openshift
  • inspect nginx imagestream
oc describe is nginx -n openshift
  • setup new project
oc new-project is-demo
  • setup the dev environment
oc new-app --name=html-dev  nginx:1.10~
oc get all
oc logs -f builds/html-dev-1
oc get svc
oc expose svc/html-dev
oc get route
  • show this app to the qa team
oc get is
oc tag docker-registry.default.svc:5000/is-demo/html-dev:latest is-demo/html-qa:1.0
oc get is
oc new-app --name=html-qa --image-stream="is-demo/html-qa:1.0"
oc expose svc/html-qa
  • now go and make some changes to the git repo, then push it to github
now lets build the latest dev release
oc start-build html-dev
oc status
oc get pods
  • check dev application for latest changes
  • check if qa application remains in desired state
  • now commit the new dev branch to qa branch
oc get is
oc tag docker-registry.default.svc:5000/is-demo/html-dev html-qa:1.1
  • change the imagestream to newer release
oc edit dc/html-qa
oc get dc
oc get pods
  • check if qa application is reflecting latest changes from v1.1
  • now we rollback the qa release to v1.0
oc edit dc/html-qa
oc get dc
oc get pods
  • check if qa application is reflecting the rollbacked version v1.0

5 database backup

5.1 mariadb (os v3.9)

  • install global backup template
oc create -f

5.2 database backup with oc

oc rsh dc/mariadb /bin/sh -i -c "MYSQL_PWD=$MYSQL_ROOT_PASSWORD /usr/bin/mysqldump -u root --skip-lock-tables \$MYSQL_DATABASE" > mysqldb.sql

6 Maintenance

6.1 CleanUp old docker images on nodes

Keeping up to three tag revisions 1, and keeping resources (images, image streams and pods) younger than sixty minutes:
oc adm prune images --keep-tag-revisions=3 --keep-younger-than=60m
Pruning every image that exceeds defined limits:
oc adm prune images --prune-over-size-limit
CopyPaste example
oc adm prune images --keep-tag-revisions=3 --keep-younger-than=60m --confirm
oc adm prune images --prune-over-size-limit --confirm