Kubernetes

Cheats and random commands

• https://kubectlcheatsheet.com/
• https://kubernetes.io/docs/reference/kubectl/quick-reference/

kubectl apply -f - <<EOF
apiVersion: v1
kind: ServiceAccount
metadata:
  name: kubectl-actions
  namespace: my-v2-restore
EOF

kubectl get all,pvc,ingress,certificaterequests,orders,certificates,secret,cronjob,configmap -n nextcloud 

kubectl describe nodes
sudo journalctl -u k3s

kubectl scale deployment my-deployment --replicas=0    

kubectl scale deployment my-deployment --replicas=3

export IP_HELLO=192.168.0.137
curl --resolve "pi5:80:$IP_HELLO" -i http://pi5

for p in $(kubectl get pods | grep Terminating | awk '{print $1}'); do kubectl delete pod $p --grace-period=0 --force;done

/etc/kubernetes/admin.conf
~/.kube/config

Nextcloud

helm repo add nextcloud https://nextcloud.github.io/helm/
helm install my-release nextcloud/nextcloud

Database Warning:

  export APP_HOST=127.0.0.1
  export APP_PASSWORD=$(kubectl get secret --namespace default my-release-nextcloud -o jsonpath="{.data.nextcloud-password}" | base64 --decode)

helm upgrade my-release nextcloud/nextcloud \
    --set nextcloud.password=$APP_PASSWORD,nextcloud.host=$APP_HOST,service.type=ClusterIP,mariadb.enabled=false,externalDatabase.user=nextcloud,externalDatabase.database=nextcloud,externalDatabase.host=YOUR_EXTERNAL_DATABASE_HOST

Cert manager

helm install \
  cert-manager jetstack/cert-manager \
  --namespace cert-manager \
  --create-namespace \
  --version v1.17.2 \
  --set crds.enabled=true

Metallb

helm repo add metallb https://metallb.github.io/metallb
helm install metallb metallb/metallb

kubectl apply -f - <<EOF
apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
  name: first-pool
  namespace: kube-system
spec:
  addresses:
  - 192.168.0.30-192.168.0.35
---
---
apiVersion: metallb.io/v1beta1
kind: L2Advertisement
metadata:
  name: l2adv
  namespace: kube-system
spec:
  ipAddressPools:
  - first-pool
EOF

make a storage class default

kubectl patch storageclass nfs-client -p '{"metadata": {"annotations":{"storageclass.kubernetes.io/is-default-class":"true"}}}'

install kubespray

git clone https://github.com/kubernetes-sigs/kubespray.git
cd kubespray
git switch -c release-2.26 origin/release-2.26

#or shorter
git clone --depth 1 --branch release-2.26 https://github.com/kubernetes-sigs/kubespray.git

Activate kubespray env snippet:

VENVDIR=kubespray-venv
python3 -m venv $VENVDIR
source $VENVDIR/bin/activate
pip install -U -r requirements.txt

ansible-playbook -i inventory/mycluster/inventory.ini --become --become-user=root cluster.yml -v

install k3s

with rights to access it as user

curl -sfL https://get.k3s.io | INSTALL_K3S_EXEC='--write-kubeconfig-mode=644' sh -
curl -sfL https://get.k3s.io | K3S_KUBECONFIG_MODE="644" INSTALL_K3S_EXEC="server" sh -s - --flannel-backend none
curl -sfL https://get.k3s.io | K3S_KUBECONFIG_MODE="644" INSTALL_K3S_EXEC="server" sh -s - --token 424242

change interface

https://jaehong21.com/posts/k3s/02-access-outside/

sudo vi /etc/systemd/system/k3s.service

ExecStart=/usr/local/bin/k3s \
    server \
        '--disable=traefik' \
        '--token' \
        '12345' \
        '--write-kubeconfig-mode=644' \
        '–advertise-address=192.168.0.137' \
        '-tls-san=192.168.0.137' \

install nginx ingress controller

https://docs.k3s.io/cluster-access

helm upgrade --install ingress-nginx ingress-nginx \
  --repo https://kubernetes.github.io/ingress-nginx \
  --namespace ingress-nginx --create-namespace

• https://github.com/rancher/rancher/issues/35053

helm upgrade --install ingress-nginx ingress-nginx \
  --repo https://kubernetes.github.io/ingress-nginx \
  --namespace ingress-nginx --create-namespace \
  --set ingressClassResource.default=true \
  --set controller.watchIngressWithoutClass=true

patch ingress controller config

kubectl patch cm ingress-nginx-controller -n ingress-nginx -p '{"data":{"annotations-risk-level":"Critical"}}'
kubectl patch cm ingress-nginx-controller -n ingress-nginx -p '{"data":{"strict-validate-path-type":"false"}}'
kubectl patch cm ingress-nginx-controller -n ingress-nginx -p '{"data":{"enable-snippet-annotations":"true"}}'

install helm

curl -fsSL -o get_helm.sh https://raw.githubusercontent.com/helm/helm/main/scripts/get-helm-3
chmod 700 get_helm.sh
./get_helm.sh

access k3s cluster via helm

export KUBECONFIG=/etc/rancher/k3s/k3s.yaml
kubectl get pods --all-namespaces
helm ls --all-namespaces

helmfile

mkdir helmfile && cd helmfile
wget https://github.com/helmfile/helmfile/releases/download/v1.0.0-rc.12/helmfile_1.0.0-rc.12_linux_amd64.tar.gz
tar xvzf helmfile_1.0.0-rc.12_linux_amd64.tar.gz
sudo mv helmfile /usr/local/bin

helmfile apply -e dev -n opendesk

helmfile apply -e dev -n opendesk -l component=collabora

install helm-diff

helm plugin install https://github.com/databus23/helm-diff

remove k3s

/usr/local/bin/k3s-uninstall.sh

show everything in a namespace

kubectl --namespace=gitlab-runner show all

get shell

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

events

kubectl get events --namespace=gitlab-runner

get all events

kubectl get events --all-namespaces  --sort-by='.metadata.creationTimestamp'

create namespace

kubectl create ns gitlab-runner

gitlab-runner

• https://github.com/ulm0/gitlab

For swep20:

cd ~/kubernetes/gitlab-runner/
helm install --namespace gitlab-runner gitlab-runner-swep20-2 -f values_swep20.yaml gitlab/gitlab-runner
helm uninstall gitlab-runner --namespace=gitlab-runner

edit configmap via editor

kubectl edit cm -n kube-system coredns

Recreate/Restart after edit:

kubectl delete pod coredns

fix gitlab-runner for docker in docker

• https://gitlab.com/gitlab-org/gitlab-runner/-/issues/2578

Edit config map and add following before runner start command:

    # Add docker volumes
    cat >> /home/gitlab-runner/.gitlab-runner/config.toml << EOF
        [[runners.kubernetes.volumes.host_path]]
              name = "alias-docker-in-docker"
              mount_path = "/var/run/docker.sock"
              read_only = true
              host_path = "/var/run/docker.sock"
    EOF

add helm charts

helm repo add stable https://charts.helm.sh/stable 
helm repo add gitlab https://charts.gitlab.io/
helm repo update

cluster info

kubectl cluster-info

delete service and deployment

• https://www.slingacademy.com/article/how-to-completely-remove-a-kubernetes-deployment-with-examples/

kubectl get all
kubectl delete svc XY
kubectl delete deployment XY
kubectl delete pod XY
kubectl delete ns XYZ