OpenShift & K8S Cheat Sheet

1 Kubernetes

1.1 Setup

1.1.1 oc

mkdir $HOME/bin ; cd $HOME/bin 
curl -L https://github.com/$(curl -L -s https://github.com/openshift/okd/releases | grep  openshift-client-linux- | head -1 | cut -d\" -f2) --output openshift-client-linux.tar.gz
tar vxfz openshift-client-linux.tar.gz
rm -f openshift-client-linux.tar.gz README.md

1.1.2 kubectl-neat

mkdir $HOME/bin ; cd $HOME/bin 
rm -f kubectl-neat
wget https://github.com/itaysk/kubectl-neat/releases/latest/download/kubectl-neat_linux_amd64.tar.gz
chmod 700 kubectl-neat
tar vxfz kubectl-neat_linux_amd64.tar.gz
rm -f LICENSE kubectl-neat_linux_amd64.tar.gz

1.1.3 kubectl

mkdir $HOME/bin ; cd $HOME/bin 
rm -f kubectl
curl -LO https://storage.googleapis.com/kubernetes-release/release/$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/linux/amd64/kubectl
chmod 700 kubectl
grep 'kubectl completion bash' $HOME/.bashrc || echo 'source <(kubectl completion bash)' >> $HOME/.bashrc

1.1.4 kustomize

cd $HOME/bin
curl -s "https://raw.githubusercontent.com/kubernetes-sigs/kustomize/master/hack/install_kustomize.sh"  | bash

1.1.5 helm

curl https://raw.githubusercontent.com/helm/helm/master/scripts/get-helm-3 | sh
grep 'helm completion bash' $HOME/.bashrc || echo 'source <(helm completion bash)' >> $HOME/.bashrc

1.2 Daily

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

1.2.1 SHELL

• Authenticate Kubectl

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

1.2.2 Use Helm

• https://artifacthub.io/
• https://hub.helm.sm/
• https://hub.kubeapps.com/

export KUBECONFIG=/etc/rancher/k3s/k3s.yaml # for K3S
helm search hub wordpress --max-col-width 120
helm repo add stable https://charts.helm.sh/stable
helm repo add bitnami https://charts.bitnami.com/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 --rule=wp.vm20.test.domain.ch/*=my-wordpress:8080

firefox https://wp.vm20.test.domain.ch/login
# 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 .bashrc

• kubectl helpers

source <(kubectl completion bash)
export PS1="# \$(kubectl config view -o jsonpath="{.contexts[].context.namespace}") $PS1"
alias kn='kubectl get ns'
alias kp='kubectl get pods'
alias ka='kubectl get all'
alias kpvc='kubectl get pvc'
alias kpv='kubectl get pv'

_knd_complete() {
    local curr_arg="${COMP_WORDS[COMP_CWORD]}"
    COMPREPLY=( $(kubectl get namespaces --no-headers -o custom-columns=":metadata.name" | grep "^$curr_arg") )
}

knd() {
    if [[ -n "$1" ]]; then
        kubectl config set-context --current --namespace="$1"
    else
        echo "Usage: knd <namespace>"
        echo "Available namespaces:"
        kubectl get namespaces --no-headers -o custom-columns=":metadata.name"
    fi
}

complete -F _knd_complete knd

kpvcc() {
    # Prompt for user input with defaults
    read -p "Name [pvc1]: " pvc_name
    pvc_name=${pvc_name:-pvc1}
    read -p "Access Modes [ReadWriteOnce]: " access_modes
    access_modes=${access_modes:-ReadWriteOnce}
    read -p "Storage [5Gi]: " storage
    storage=${storage:-5Gi}
    # Apply the PVC using inline YAML
    kubectl apply -f - <<EOF
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: $pvc_name
spec:
  accessModes:
    - $access_modes
  resources:
    requests:
      storage: $storage
  storageClassName: local-path
EOF

    echo "PVC '$pvc_name' created with AccessModes='$access_modes' and Storage='$storage'"
}

1.3 Deploy

1.3.1 Create Secret

username=myuser
read password

kubectl create secret generic db-user-pass --from-literal=username=$username --from-literal=password="$password"

kubectl get secret db-user-pass -o jsonpath='{.data.password}' | base64 --decode

----REF IN POD------
    env:
       - name: SECRET_USERNAME
         valueFrom:
           secretKeyRef:
             name: db-user-pass
             key: username

1.3.2 Create and change into Namespace

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

1.3.3 Deploy Docker Container and Expose Service

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

1.3.4 Inject VARS into Deployment/Container

kubectl edit deployment nginx1

spec:
  containers:
  - name: nginx
    image: nginx:1.7.9
    env:
    - name: MY_VAT
      value: MY_VALUE

1.3.5 Get Environment VARS of Pod

kubectl exec pod-name -- printenv

1.3.6 Expose Container Port as Service

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

1.3.7 Create Ingress Rule for Service

kubectl create ingress ingress-www --rule=www.domain.com/*=nginx-service:8080

1.3.8 Docker Pull Secret

oc create secret docker-registry docker --docker-server=docker.io --docker-username=username1 --docker-email=chris@domain.ch --docker-password=xcgsedfgsdfhgsdfg
oc secrets link default docker --for=pull
oc new-app --name wiki --image image.registry.tld/image:tag --source-secret=docker

1.4 Change/Update

1.4.1 Force Deployment to pull (latest)

oc get deployments
oc set env deployment/myapp UPDATE_TIMESTAMP="$(date)"
oc rollout status deployment/myapp
oc describe pod [POD_NAME]

1.5 Configure

1.5.1 Traefik Config

- https://levelup.gitconnected.com/a-guide-to-k3s-ingress-using-traefik-with-nodeport-6eb29add0b4b

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

1.6 Debug

1.6.1 Run Container with custom Command

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

1.6.2 Attach Container in Pod (log)

kubectl attach busybox -c busybox -i -t

1.6.3 Jump into Pods Shell

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

1.6.4 Get all Containers on all Namespaces

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

1.6.5 Get all Containers grouped by Pods for all Namespaces

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

1.6.6 Open Firewall for NodePort (non persistent)

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

2 OpenShift

2.1 Install

2.1.1 OC & KUBECTL (OKD)

mkdir $HOME/bin ; cd $HOME/bin 
rm -f oc
wget https://github.com/$(curl -L https://github.com/openshift/okd/releases/latest/ | grep openshift-client-linux | grep href= | cut -d\" -f2 )
tar vxfz openshift-client-linux-*.tar.gz
rm -rf README.md 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
wget https://mirror.openshift.com/pub/openshift-v4/clients/oc/latest/linux/oc.tar.gz
tar vxfz oc.tar.gz 
rm -f README.md 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 .bashrc

genpasswd() {
   local l=$1
   [ "$l" == "" ] && l=16
   tr -dc A-Za-z0-9_=., < /dev/urandom | head -c ${l} | xargs
}

source <(kubectl completion bash)
export PS1="# \$(kubectl config view -o jsonpath="{.contexts[].context.namespace}") $PS1"

_knd_complete() {
    local curr_arg="${COMP_WORDS[COMP_CWORD]}"
    COMPREPLY=( $(kubectl get namespaces --no-headers -o custom-columns=":metadata.name" | grep "^$curr_arg") )
}

knd() {
    if [[ -n "$1" ]]; then
        kubectl config set-context --current --namespace="$1"
    else
        echo "Usage: knd <namespace>"
        echo "Available namespaces:"
        kubectl get namespaces --no-headers -o custom-columns=":metadata.name"
    fi
}

complete -F _knd_complete knd

alias knl='kubectl get ns'
alias kp='kubectl get pods'
alias ka='kubectl get all'
alias kpvc='kubectl get pvc'
alias kpv='kubectl get pv'

kpvcc() {
    # Prompt for user input with defaults
    read -p "Name [pvc1]: " pvc_name
    pvc_name=${pvc_name:-pvc1}

    read -p "Access Modes [ReadWriteOnce]: " access_modes
    access_modes=${access_modes:-ReadWriteOnce}

    read -p "Storage [5Gi]: " storage
    storage=${storage:-5Gi}

    # Apply the PVC using inline YAML
    kubectl apply -f - <<EOF
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: $pvc_name
spec:
  accessModes:
    - $access_modes
  resources:
    requests:
      storage: $storage
  storageClassName: standard
EOF

    echo "PVC '$pvc_name' created with AccessModes='$access_modes' and Storage='$storage'"
}

2.2 Debug

2.2.1 etcd

M1=$(oc get nodes -l node-role.kubernetes.io/master  | grep Ready | head -1 | cut -d' ' -f1 )
oc rsh -n openshift-etcd etcd-$M1  <<EOF                                        
etcdctl member list -w table
EOF

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~https://github.com/joe-speedboat/openshift.html.devops.git#master
oc get all
oc logs -f builds/html-dev-1

oc get svc
oc expose svc/html-dev --hostname=html-dev.app.domain.com
oc get route

curl http://html-dev.app.domain.com

• 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 --hostname=html-qa.app.domain.com
curl html-qa.app.domain.com

• 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

curl http://html-dev.app.domain.com

• check if qa application remains in desired state

curl html-qa.app.domain.com

• 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

curl html-qa.app.domain.com

• 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

curl html-qa.app.domain.com

5 database backup

5.1 mariadb

• install global backup template

oc create -f https://raw.githubusercontent.com/joe-speedboat/openshift.mariadb-backup-cronjob/master/mariadb-backup-template_okd410.yaml

• more information can be found on git repo mariadb-backup-cronjob

5.2 mariadb 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

oc rsh deployments/mariadb /bin/bash -i -c "MYSQL_PWD=\$MARIADB_ROOT_PASSWORD /usr/bin/mysqldump -u root --skip-lock-tables \$MYSQL_DATABASE" > mariadb.sql

5.3 postgresql dump with kubectl

kubectl exec zammad-postgresql-0 -- bash -c "PGPASSWORD="xxx" pg_dump -Uzammad zammad_production" > zammad_production.sql

6 Maintenance

6.1 Databases

6.1.1 Mariadb login

MYSQL_PWD="$MARIADB_ROOT_PASSWORD" mysql -u root $MYSQL_DATABASE

6.1.2 mysql login

 mysql -u $MYSQL_USER -p"$MYSQL_PASSWORD" $MYSQL_DATABASE

6.2 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