[KUBEADM] 01.cluster init

cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo

[kubernetes]

name=Kubernetes

baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-\$basearch

enabled=1

gpgcheck=1

repo_gpgcheck=1

gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg

exclude=kubelet kubeadm kubectl

EOF

sudo yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes

sudo systemctl enable --now kubelet

systemctl daemon-reload

systemctl restart kubelet

[root@master01 ~]# kubeadm init

W1204 19:03:38.547621   16877 configset.go:348] WARNING: kubeadm cannot validate component configs for API groups [kubelet.config.k8s.io kubeproxy.config.k8s.io]

[init] Using Kubernetes version: v1.19.4

[preflight] Running pre-flight checks

[WARNING Firewalld]: firewalld is active, please ensure ports [6443 10250] are open or your cluster may not function correctly

[WARNING Hostname]: hostname "master01" could not be reached

[WARNING Hostname]: hostname "master01": lookup master01 on 192.168.1.1:53: no such host

[preflight] Pulling images required for setting up a Kubernetes cluster

[preflight] This might take a minute or two, depending on the speed of your internet connection

[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'

[certs] Using certificateDir folder "/etc/kubernetes/pki"

[certs] Generating "ca" certificate and key

[certs] Generating "apiserver" certificate and key

[certs] apiserver serving cert is signed for DNS names [kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local master01] and IPs [10.96.0.1 192.168.1.109]

[certs] Generating "apiserver-kubelet-client" certificate and key

[certs] Generating "front-proxy-ca" certificate and key

[certs] Generating "front-proxy-client" certificate and key

[certs] Generating "etcd/ca" certificate and key

[certs] Generating "etcd/server" certificate and key

[certs] etcd/server serving cert is signed for DNS names [localhost master01] and IPs [192.168.1.109 127.0.0.1 ::1]

[certs] Generating "etcd/peer" certificate and key

[certs] etcd/peer serving cert is signed for DNS names [localhost master01] and IPs [192.168.1.109 127.0.0.1 ::1]

[certs] Generating "etcd/healthcheck-client" certificate and key

[certs] Generating "apiserver-etcd-client" certificate and key

[certs] Generating "sa" key and public key

[kubeconfig] Using kubeconfig folder "/etc/kubernetes"

[kubeconfig] Writing "admin.conf" kubeconfig file

[kubeconfig] Writing "kubelet.conf" kubeconfig file

[kubeconfig] Writing "controller-manager.conf" kubeconfig file

[kubeconfig] Writing "scheduler.conf" kubeconfig file

[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"

[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"

[kubelet-start] Starting the kubelet

[control-plane] Using manifest folder "/etc/kubernetes/manifests"

[control-plane] Creating static Pod manifest for "kube-apiserver"

[control-plane] Creating static Pod manifest for "kube-controller-manager"

[control-plane] Creating static Pod manifest for "kube-scheduler"

[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"

[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s

[apiclient] All control plane components are healthy after 31.017563 seconds

[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace

[kubelet] Creating a ConfigMap "kubelet-config-1.19" in namespace kube-system with the configuration for the kubelets in the cluster

[upload-certs] Skipping phase. Please see --upload-certs

[mark-control-plane] Marking the node master01 as control-plane by adding the label "node-role.kubernetes.io/master=''"

[mark-control-plane] Marking the node master01 as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]

[bootstrap-token] Using token: z51nf9.1g3ai062038ztpx9

[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles

[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to get nodes

[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials

[bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token

[bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster

[bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace

[kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key

[addons] Applied essential addon: CoreDNS

[addons] Applied essential addon: kube-proxy

Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

  mkdir -p $HOME/.kube

  sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config

  sudo chown $(id -u):$(id -g) $HOME/.kube/config

You should now deploy a pod network to the cluster.

Run "kubectl apply -f [podnetwork].yaml" with one of the options listed at:

  https://kubernetes.io/docs/concepts/cluster-administration/addons/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 192.168.1.109:6443 --token z51nf9.1g3ai062038ztpx9 \

    --discovery-token-ca-cert-hash sha256:3781a245e9c470155ad0c2b6b4934758aa9294ce5b0ed0c56c5e124d35bb8acf 

https://computingforgeeks.com/install-kubernetes-cluster-on-centos-with-kubeadm/