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Kubernetes : Configure Master Node
2015/12/13 |
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Install Kubeadm to Configure Multi Nodes Kubernetes Cluster.
This example is based on the emvironment like follows.
For System requirements, each Node has uniq Hostname, MAC address, Product_uuid.
MAC address and Product_uuid are generally already uniq one if you installed OS on phisical machine or virtual machine with common procedure. You can see Product_uuid with the command [dmidecode -s system-uuid].
-----------+---------------------------+--------------------------+------------
| | |
eth0|10.0.0.30 eth0|10.0.0.51 eth0|10.0.0.52
+----------+-----------+ +-----------+----------+ +-----------+----------+
| [ dlp.srv.world ] | | [ node01.srv.world ] | | [ node02.srv.world ] |
| Master Node | | Worker Node | | Worker Node |
+----------------------+ +----------------------+ +----------------------+
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| [1] |
| [2] |
Configure initial setup on Master Node.
For [--apiserver-advertise-address] option, specify the IP address Kubernetes API server listens.
For [--pod-network-cidr] option, specify network which Pod Network uses.
There are some plugins for Pod Network. (refer to details below)
⇒ https://kubernetes.io/docs/concepts/cluster-administration/networking/
On this example, select Flannel. For Flannel, specify [--pod-network-cidr=10.244.0.0/16] to let Pod Network work normally.
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[root@dlp ~]# kubeadm init --apiserver-advertise-address=10.0.0.30 --pod-network-cidr=10.244.0.0/16
[init] Using Kubernetes version: v1.21.1
[preflight] Running pre-flight checks
[WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/
[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 [dlp.srv.world kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.0.0.30]
.....
.....
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
Alternatively, if you are the root user, you can run:
export KUBECONFIG=/etc/kubernetes/admin.conf
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:
# the command below is necessary to run on Worker Node when he joins to the cluster, so remember it
kubeadm join 10.0.0.30:6443 --token 31eeyr.uxvpz3b0teajkaki \
--discovery-token-ca-cert-hash sha256:f2caf4fe6f26dc6cc8188b55ee3c825e5b8d9779a61bfd4eda4b152627e56184
# set cluster admin user # if you set common user as cluster admin, login with it and run [sudo cp/chown ***] [root@dlp ~]# mkdir -p $HOME/.kube [root@dlp ~]# cp -i /etc/kubernetes/admin.conf $HOME/.kube/config [root@dlp ~]# chown $(id -u):$(id -g) $HOME/.kube/config
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| [3] | Configure Pod Network with Flannel. |
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[root@dlp ~]# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml master/Documentation/kube-flannel.yml /raw.githubusercontent.com/coreos/flannel/ podsecuritypolicy.policy/psp.flannel.unprivileged created clusterrole.rbac.authorization.k8s.io/flannel created clusterrolebinding.rbac.authorization.k8s.io/flannel created serviceaccount/flannel created configmap/kube-flannel-cfg created daemonset.apps/kube-flannel-ds created # show state ⇒ OK if STATUS = Ready [root@dlp ~]# kubectl get nodes NAME STATUS ROLES AGE VERSION dlp.srv.world Ready control-plane,master 2m4s v1.21.1 # show state ⇒ OK if all are Running [root@dlp ~]# kubectl get pods --all-namespaces NAMESPACE NAME READY STATUS RESTARTS AGE kube-system coredns-558bd4d5db-f8cvh 1/1 Running 0 117s kube-system coredns-558bd4d5db-tg8v6 1/1 Running 0 117s kube-system etcd-dlp.srv.world 1/1 Running 0 2m6s kube-system kube-apiserver-dlp.srv.world 1/1 Running 0 2m6s kube-system kube-controller-manager-dlp.srv.world 1/1 Running 0 2m6s kube-system kube-flannel-ds-wdvpn 1/1 Running 0 56s kube-system kube-proxy-wzh69 1/1 Running 0 117s kube-system kube-scheduler-dlp.srv.world 1/1 Running 0 2m6s |