Kubernetes

Installation

https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/#installing-kubeadm-kubelet-and-kubectl

sudo apt-get update
sudo apt-get install -y apt-transport-https ca-certificates curl
sudo mkdir -p /etc/apt/keyrings
sudo curl -fsSL https://pkgs.k8s.io/core:/stable:/v1.30/deb/Release.key | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-apt-keyring.gpg
sudo echo 'deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.30/deb/ /' | sudo tee /etc/apt/sources.list.d/kubernetes.list
sudo apt-get update
sudo apt-get install -y kubelet kubeadm kubectl
sudo apt-mark hold kubelet kubeadm kubectl

Шпаргалка по командам

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minikube start --mount-string="$HOME/go/src/github.com/nginx:/data" --mount --driver=docker
minikube ip
kubectl cluster-info
kubectl create deployment nginx-depl --image=nginx
kubectl get pod
kubectl get replicaset
kubectl get pod <POD-ID> -o wide
kubectl get deployment nginx-depl
kubectl get deployment nginx-depl -o yaml
kubectl edit deployment nginx-depl
kubectl logs <POD-ID>
kubectl describe pod <POD-ID>
kubectl exec -it <POD-ID> -- /bin/bash
kubectl apply -f <CONFIG.YML>
kubectl get deployment nginx-deployment -o yaml
# https://kubernetes.github.io/ingress-nginx/troubleshooting/
kubectl get ingress -n mongo-admin
kubectl describe ing mongo-express-ingress -n mongo-admin
kubectl describe ingress mongo-express-ingress -n mongo-admin
kubectl rollout restart deployment <deployment_name> -n <namespace>

kubectl delete --all pods --namespace=kubernetes-dashboard

System reset

minikube stop
minikube delete
rm -rf ~/.minikube
rm -rf ~/.kube
docker kill $(docker ps -q)
docker rm $(docker ps -a -q)
docker rmi $(docker images -q)
docker system prune

Setup cluster

sudo su
swapoff -a
kubeadm reset
kubeadm init

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

sudo systemctl start docker
sudo swapoff -a
sudo mv /etc/containerd/config.toml  /etc/containerd/config222.toml
sudo kubeadm reset --force
sudo kubeadm init --pod-network-cidr=10.244.0.0/16
/run/flannel/subnet.env

FLANNEL_NETWORK=10.244.0.0/16
FLANNEL_SUBNET=10.244.0.1/24
FLANNEL_MTU=1450
FLANNEL_IPMASQ=true

kubectl apply -f https://github.com/flannel-io/flannel/releases/latest/download/kube-flannel.yml

kubectl taint nodes --all node-role.kubernetes.io/control-plane-
kubectl taint nodes --all node.kubernetes.io/disk-pressure-
kubectl taint nodes --all node.kubernetes.io/not-ready-

-- FORCE SHUTDOWN POD
kubectl delete pod <PODNAME> --grace-period=0 --force --namespace <NAMESPACE>

Translate a Docker Compose File to Kubernetes Resources

• https://kubernetes.io/docs/tasks/configure-pod-container/translate-compose-kubernetes/

Helm

https://helm.sh/docs/intro/install/

Clear space / Remove unused images

crictl rmi --prune
docker image prune -a

Ansible

• https://kubernetes.io/blog/2019/03/15/kubernetes-setup-using-ansible-and-vagrant/
• https://habr.com/ru/companies/slurm/articles/810933/

Container Network Interface

• https://daily.dev/blog/kubernetes-cni-comparison-flannel-vs-calico-vs-canal
• https://kubevious.io/blog/post/comparing-kubernetes-container-network-interface-cni-providers

Ingress

• https://kubernetes.io/docs/concepts/services-networking/ingress/

Complete Reset

kubeadm reset
systemctl stop kubelet
systemctl stop docker
rm -rf /etc/cni/net.d/
rm -rf /var/lib/cni/
rm -rf /var/lib/kubelet/*
rm -rf /run/flannel
rm -rf /etc/cni/
ip link set cni0 down
ip link delete cni0
brctl delbr cni0
ifconfig flannel.1 down
systemctl start docker

Troubleshooting

Check status

kubectl version

kubectl config view

apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: DATA+OMITTED
    server: https://192.168.0.64:6443
  name: kubernetes
contexts:
- context:
    cluster: kubernetes
    user: kubernetes-admin
  name: kubernetes-admin@kubernetes
current-context: kubernetes-admin@kubernetes
kind: Config
preferences: {}
users:
- name: kubernetes-admin
  user:
    client-certificate-data: DATA+OMITTED
    client-key-data: DATA+OMITTED

kubectl cluster-info

Kubernetes control plane is running at https://192.168.0.64:6443
CoreDNS is running at https://192.168.0.64:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

kubectl describe node -A

kubectl get pod -A

NAMESPACE      NAME                                       READY   STATUS    RESTARTS      AGE
kube-flannel   kube-flannel-ds-tt45j                      1/1     Running   5 (65m ago)   80m
kube-system    coredns-76f75df574-rzth2                   1/1     Running   2 (65m ago)   87m
kube-system    coredns-76f75df574-xvdl6                   1/1     Running   2 (65m ago)   87m
kube-system    etcd-x570-aorus-ultra                      1/1     Running   2 (65m ago)   87m
kube-system    kube-apiserver-x570-aorus-ultra            1/1     Running   2 (65m ago)   87m
kube-system    kube-controller-manager-x570-aorus-ultra   1/1     Running   9 (65m ago)   87m
kube-system    kube-proxy-lm95s                           1/1     Running   2 (65m ago)   87m
kube-system    kube-scheduler-x570-aorus-ultra            1/1     Running   9 (65m ago)   87m

CoreDNS does not run

Check node is ready

kubectl get node -A

If not check it's status and Taints: should be <none>

kubectl describe node x570-aorus-ultra

If not do

nano /var/lib/kubelet/config.yaml

and add at the end

evictionHard:
    memory.available:  "100Mi"
    nodefs.available:  "2%"
    nodefs.inodesFree: "2%"
    imagefs.available: "2%"

save and do

systemctl restart containerd
systemctl restart kubelet

Flannel does not run

In logs

Failed to check br_netfilter: stat /proc/sys/net/bridge/bridge-nf-call-iptables: no such file or directory

modprobe br_netfilter
echo "br_netfilter" >> /etc/modules