yum remove podman* -y
yum remove buildah* -y

kubectl get namespace "<NAMESPACE>" -o json | tr -d "\n" | sed "s/\"finalizers\": \[[^]]\+\]/\"finalizers\": []/" | kubectl replace --raw /api/v1/namespaces/<NAMESPACE>/finalize -f -

cp ssl.crt /usr/local/share/ca-certificates/
update-ca-certificates
service docker restart

sudo cp -p ssl.crt /etc/pki/ca-trust/source
sudo cp ssl.crt /etc/pki/ca-trust/source/anchors/myregistrydomain.com.crt
sudo update-ca-trust extract
sudo systemctl daemon-reload
sudo systemctl restart docker

$ sudo vi /etc/docker/daemon.json

{
  "data-root":"/docker-data",
  "insecure-registries":["nexusdocker.kurumunadresi.com.tr"],
  "registry-mirrors":["https://nexusdocker.kurumunadresi.com.tr"],
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "100m"
  },
  "storage-driver": "overlay2"
}

kubectl apply -f https://k8s.io/examples/admin/dns/dnsutils.yaml
kubectl get pods dnsutils
kubectl exec -i -t dnsutils -- nslookup kubernetes.default

Server: 10.0.0.10
Address 1: 10.0.0.10

Name: kubernetes.default
Address 1: 10.0.0.1

Server: 10.96.0.10
Address 1: 10.96.0.10
nslookup: can't resolve 'kubernetes.default'
command terminated with exit code 1

$ kubectl exec -ti dnsutils -- cat /etc/resolv.conf

nameserver 10.96.0.10
search default.svc.cluster.local svc.cluster.local cluster.local kurum.gov.tr
options ndots:5

nameserver 10.96.0.10
search default.svc.cluster.local svc.cluster.local cluster.local
options ndots:5

kubectl rollout restart -n kube-system deployment/coredns

sudo rm /etc/resolv.conf
sudo ln -s /run/systemd/resolve/resolv.conf /etc/resolv.conf
sudo systemctl restart systemd-resolved
ls -l /etc/resolv.conf
cat /etc/resolv.conf

kubectl -n kube-system rollout restart deployment coredns

$ sudo mkdir -p /etc/cni/net.d
$ sudo vi /etc/cni/net.d/10-flannel.conflist

{
  "name": "cbr0",
  "plugins": [
    {
      "type": "flannel",
      "delegate": {
        "hairpinMode": true,
        "isDefaultGateway": true
      }
    },
    {
      "type": "portmap",
      "capabilities": {
        "portMappings": true
      }
    }
  ]
}

{
  "name": "cbr0",
  "cniVersion": "0.3.1",
  "plugins": [
    {
      "type": "flannel",
      "delegate": {
        "isDefaultGateway": true
      }
    },
    {
      "type": "portmap",
      "capabilities": {
        "portMappings": true
      }
    }
  ]
}

sudo chmod -Rf 777 /etc/cni /etc/cni/*
sudo chown -Rf apinizer:apinizer /etc/cni /etc/cni/*
sudo systemctl daemon-reload
sudo systemctl restart kubelet

#Hala imaj çekemeyen pod var mı kontrolü:
kubectl get pods -n kube-system
describe pod podAdi -n kube-system

sudo kubeadm alpha certs check-expiration
sudo kubeadm alpha certs renew all
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
#all the master/control-plane nodes
sudo reboot -i

sudo swapoff -a
sudo vi /etc/fstab (swap satırı kapatılacak ya da silinecek)
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
sudo reboot (isteğe bağlı)

cd /etc/kubernetes/pki/
sudo mkdir /tmp/backup | sudo mkdir /tmp/backup2
sudo mv {apiserver.crt,apiserver-etcd-client.key,apiserver-kubelet-client.crt,front-proxy-ca.crt,front-proxy-client.crt,front-proxy-client.key,front-proxy-ca.key,apiserver-kubelet-client.key,apiserver.key,apiserver-etcd-client.crt} /tmp/backup/
sudo kubeadm init phase certs all --apiserver-advertise-address <MASTER_NODE_IP>
cd /etc/kubernetes/
sudo mv {admin.conf,controller-manager.conf,kubelet.conf,scheduler.conf} /tmp/backup2
sudo kubeadm init phase kubeconfig all
sudo systemctl restart docker && sudo systemctl restart containerd && sudo systemctl restart kubelet

# Önce problemli worker node cluster'dan çıkarılır
kubectl delete node <WORKER_NODE_NAME>

# Ardından yeni bir join token oluşturulur
sudo kubeadm token create --print-join-command

# Kubernetes yapılandırması sıfırlanır.
sudo kubeadm reset

# Master'dan alınan join komutunu çalıştırılır.
sudo kubeadm join <MASTER_IP>:<PORT> --token <TOKEN> --discovery-token-ca-cert-hash sha256:<HASH>

ctr --namespace k8s.io images pull xxx.harbor.com/apinizercloud/managerxxxx -skip-verify

spec:
  topologySpreadConstraints:
    - maxSkew: 1
      topologyKey: kubernetes.io/hostname
      whenUnsatisfiable: ScheduleAnyway
      labelSelector:
        matchExpressions:
          - key: node-role.kubernetes.io/control-plane
            operator: DoesNotExist

kubectl get nodes --show-labels

kubelet --node-status-update-frequency=5s

kube-apiserver --node-monitor-grace-period=20s

kube-controller-manager --pod-eviction-timeout=2m

sudo kubeadm reset
sudo rm -rf $HOME/.kube

rm -rf /var/lib/cni/
rm -rf /var/lib/kubelet/*
rm -rf /etc/cni/
ifconfig cni0 down && ip link delete cni0
ifconfig flannel.1 down && ip link delete flannel.1
systemctl restart containerd && systemctl restart kubelet

---RHEL için machine-id değiştirme komutu---
rm -f /etc/machine-id
systemd-machine-id-setup

---Ubuntu için machine-id değiştirme komutu---
rm -f /etc/machine-id /var/lib/dbus/machine-id
systemd-machine-id-setup
cat /etc/machine-id > /var/lib/dbus/machine-id

kubeadm token create --print-join-command

kubectl get nodes
kubectl drain <NODES_OLD_HOSTNAME> --ignore-daemonsets --delete-emptydir-data
kubectl delete node <NODES_OLD_HOSTNAME>

sudo kubeadm reset
sudo hostnamectl set-hostname <NODES_NEW_HOSTNAME>
sudo reboot

hostname

# /etc/hosts üzerinde 127.0.0.1 ip'sine karşılık eski hostname duruyorsa bu kısım da yeni hostname ile değiştirilmelidir.
sudo vi /etc/hosts
rm -rf /var/lib/cni/
rm -rf /var/lib/kubelet/*
rm -rf /etc/cni/
systemctl stop kubelet && systemctl stop containerd
ifconfig cni0 down && ip link delete cni0
ifconfig flannel.1 down && ip link delete flannel.1
systemctl restart containerd && systemctl restart kubelet

kubeadm token create --print-join-command

node.kubernetes.io/unschedulable:NoSchedule

sudo reboot

kubectl taint nodes <node-name> node.kubernetes.io/unschedulable:NoSchedule-

kubectl uncordon <node-name>

# İmajın varlığı ve inspectin çalıştığı kontrol edilir.
docker inspect k8s.gcr.io/kube-scheduler:v1.18.20

# Docker versiyonu kontrol edilir.
docker --version

# Mevcut docker paketleri kaldırılır
sudo apt remove -y docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

# Uygun docker versiyonlarını listelelenir
apt-cache madison docker-ce | grep 19.03

# Docker 19.03 sürümünü kurulur
sudo apt install -y docker-ce=5:19.03.15~3-0~ubuntu-focal \
    docker-ce-cli=5:19.03.15~3-0~ubuntu-focal \
    containerd.io

# Versiyon kontrol edilir.
docker --version

# Yanlış güncelleme yapılmasını engellemek için paketler hold komutu ile sabitlenir.
sudo apt-mark hold docker-ce docker-ce-cli containerd.io

# Docker ve kubelet servisleri restart edilir.
sudo systemctl restart docker.service
sudo systemctl restart kubelet.service

sudo vi /etc/sysctl.d/k8s.conf

net.bridge.bridge-nf-call-iptables = 1

sudo sysctl --system

sudo sysctl net.bridge.bridge-nf-call-iptables

kubectl delete pod -n kube-system -l k8s-app=kube-proxy