How to Deploy a HA Kubernetes Cluster with kubeadm on CentOS7

Kubernetes is one of the most popular open source container orchestration systems. It’s used to manage the whole life of containerized applications, including deployment, scaling, upgrading etc.

Sometimes you want a Kubernetes cluster to test an application or to create a development environment quickly and easily. Kubernetes community created a tool named Kubeadm for this purpose. It greatly simplified Kubernetes deployment process. This article demonstrate how to create a simple Kubernetes cluster on CentOS7, which is able to pass Kubernetes Conformance tests, using Kubeadm. We have another article for setting up Kubernetes on Ubuntu16.04 servers. You can refer to it if you prefer Ubuntu as your Operating System.

Architecture Designing

Our example cluster consists of 5 servers in an internal network 192.168.100.0/24. Out of the 5 servers, three will be the masters nodes with IPs 192.168.100.10, 192.168.100.20, 192.168.100.30, respectively. The other two will be worker nodes and have the IPs 192.168.100.40 and 192.168.100.50, 192.168.100.60 is used as a virtual IP for Master services. You can choose to different IPs according to your own network environment. Kubernetes cluster is highly configurable. Many of its components is optional. Our deployment consists of the following components: Kubernetes, Etcd, Docker, Flannel, Helm and Nginx-ingress-controller.

Here is the server inventory and architecture

Server Name IP Address Role
Master01 192.168.100.10 Master Node
Master02 192.168.100.20 Master Node
Master03 192.168.100.30 Master Node
Node01 192.168.100.40 Worker Node
Node02 192.168.100.50 Worker Node
how-to-deploy-a-highly-available-kubernetes-cluster-with-kubeadm-on-CentOS7

Prerequisites

The servers could be bare-metal servers or virtual servers. They have the following requirements:

  • Each server has at least 2 CPU/vCPU cours, 4GB RAM and 10GB disk space.
  • All servers must have Internet access in order to download software packages.
  • Operating System on them is CentOS7 with root user enabled.

Preparing Servers

There are a few things to be done to get the servers ready. You need to perform the following task on all servers

1. Disable the Selinux


# setenforce 0
# sed -i 's/SELINUX=permissive/SELINUX=disabled/' /etc/sysconfig/selinux

2. Disable firewalld


# systemctl disable firewalld
# systemctl stop firewalld
    

3. Disable swap


# swapoff -a
# sed -i 's/^.*swap/#&/' /etc/fstab                 

4. Enable Forwarding


# iptables -P FORWARD ACCEPT

# cat <  /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
vm.swappiness=0
EOF
    
# sysctl --system              

Edit /etc/hosts file to contain the following:


master01 192.168.100.10
master02 192.168.100.20
master03 192.168.100.30      

5. Install and configure Docker


# wget https://download.docker.com/linux/static/stable/x86_64/docker-17.03.2-ce.tgz
# tar -zxvf docker-17.03.2-ce.tgz
# cd docker
# cp * /usr/local/bin                 

Change the content of /etc/systemd/system/docker.service to the following


[Unit]
Description=Docker Application Container Engine
Documentation=http://docs.docker.io
[Service]
ExecStart=/usr/local/bin/dockerd 
ExecStartPost=/sbin/iptables -I FORWARD -s 0.0.0.0/0 -j ACCEPT
ExecReload=/bin/kill -s HUP $MAINPID
Restart=on-failure
RestartSec=5
LimitNOFILE=infinity
LimitNPROC=infinity
LimitCORE=infinity
Delegate=yes
KillMode=process
[Install]
WantedBy=multi-user.target

Enable Docker service and reload configuration by running the following commands


# systemctl daemon-reload 
# systemctl enable docker 
# systemctl restart docker

6. Install kubeadm, kubectl and kubelet


#  cat <  /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64
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
EOF

# yum makecache fast && yum install -y kubelet-1.10.0-0 kubeadm-1.10.0-0 kubectl-1.10.0-0

#  cat <  /etc/systemd/system/kubelet.service.d/10-kubeadm.conf
Environment="KUBELET_CGROUP_ARGS=--cgroup-driver=cgroupfs"
EOF

# systemctl daemon-reload 
# systemctl enable kubelet 
# systemctl restart kubelet

Setting Up Kubernetes Cluster

Generating Master Configuration Files

We generate one set of configuration files on Master01(192.168.100.10) and copy them onto all Master nodes.

Download Cloudflare's PKI and TLS toolkit


# curl -o /usr/local/bin/cfssl https://pkg.cfssl.org/R1.2/cfssl_linux-amd64
# curl -o /usr/local/bin/cfssljson https://pkg.cfssl.org/R1.2/cfssljson_linux-amd64
# chmod +x /usr/local/bin/cfssl*

Create a certificates folder


# mkdir /opt/ssl

Create a certificate configuration file /opt/ssl/ca-config.json with following content


{
  "signing": {
    "default": {
      "expiry": "87600h"
    },
    "profiles": {
      "kubernetes": {
        "usages": [
            "signing",
            "key encipherment",
            "server auth",
            "client auth"
        ],
        "expiry": "87600h"
      }
    }
  }
}
vi ca-csr.json
{
  "CN": "kubernetes",
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "US",
      "ST": "TX",
      "L": "dallas",
      "O": "k8s",
      "OU": "System"
    }
  ]
}
vi etcd-csr.json
{
      "CN": "etcd",
  "hosts": [
    "127.0.0.1",
    "192.168.100.10",
    "192.168.100.20",
    "192.168.100.30"
  ],
  "key": {
    "algo": "rsa",
    "size": 2048
  },
  "names": [
    {
      "C": "US",
      "ST": "TX",
      "L": "dallas",
      "O": "k8s",
      "OU": "System"
    }
  ]
}

Generate certificates


# cd /opt/ssl/ca-config.json
# cfssl gencert -initca ca-csr.json | cfssljson -bare ca
# cfssl gencert -ca=ca.pem -ca-key=ca-key.pem -config=ca-config.json -profile=kubernetes etcd-csr.json | cfssljson -bare etcd

Copy Configuration Files to Installation Folder

To copy configuration files generated in the last step to installation folder, you need to perform the following tasks on all 3 Master nodes.

Create the certificate folder


# mkdir -p /etc/etcd/ssl

Create the etcd data director


# mkdir -p /var/lib/etcd

Copy etcd certificates from master node “Master01”


# scp -rp 192.168.100.10:/opt/ssl/*.pem /etc/etcd/ssl/

Install etcd


# wget https://github.com/coreos/etcd/releases/download/v3.3.4/etcd-v3.3.4-linux-amd64.tar.gz
# tar -zxvf etcd-v3.3.4-linux-amd64.tar.gz
# cp etcd-v3.3.4-linux-amd64/etcd* /usr/local/bin/

Setting Up ETCD Cluster

On Master01:

Create file /etc/systemd/system/etcd.service with the following content


[Unit]
Description=Etcd Server
After=network.target
After=network-online.target
Wants=network-online.target
Documentation=https://github.com/coreos
[Service]
Type=notify
WorkingDirectory=/var/lib/etcd/
ExecStart=/usr/local/bin/etcd \
--name=master01 \
--cert-file=/etc/etcd/ssl/etcd.pem \
--key-file=/etc/etcd/ssl/etcd-key.pem \
--peer-cert-file=/etc/etcd/ssl/etcd.pem \
--peer-key-file=/etc/etcd/ssl/etcd-key.pem \
--trusted-ca-file=/etc/etcd/ssl/ca.pem \
--peer-trusted-ca-file=/etc/etcd/ssl/ca.pem \
--initial-advertise-peer-urls=https://192.168.100.10:2380 \
--listen-peer-urls=https://192.168.100.10:2380 \
--listen-client-urls=https://192.168.100.10:2379,http://127.0.0.1:2379 \
--advertise-client-urls=https://192.168.100.10:2379 \
--initial-cluster-token=etcd-cluster-0 \
--initial-cluster=master01=https://192.168.100.10:2380,master02=https://192.168.100.20:2380,master03=https://192.168.100.30:2380\
--initial-cluster-state=new \
--data-dir=/var/lib/etcd
Restart=on-failure
RestartSec=5
LimitNOFILE=65536
[Install]
WantedBy=multi-user.target

Start etcd service


systemctl daemon-reload && systemctl enable etcd && systemctl start etcd

On Master02

Create file /etc/systemd/system/etcd.service with the following content


[Unit]
Description=Etcd Server
After=network.target
After=network-online.target
Wants=network-online.target
Documentation=https://github.com/coreos
[Service]
Type=notify
WorkingDirectory=/var/lib/etcd/
ExecStart=/usr/local/bin/etcd \
--name=master02 \
--cert-file=/etc/etcd/ssl/etcd.pem \
--key-file=/etc/etcd/ssl/etcd-key.pem \
--peer-cert-file=/etc/etcd/ssl/etcd.pem \
--peer-key-file=/etc/etcd/ssl/etcd-key.pem \
--trusted-ca-file=/etc/etcd/ssl/ca.pem \
--peer-trusted-ca-file=/etc/etcd/ssl/ca.pem \
--initial-advertise-peer-urls=https://192.168.100.20:2380 \
--listen-peer-urls=https://192.168.100.20:2380 \
--listen-client-urls=https://192.168.100.20:2379,http://127.0.0.1:2379 \
--advertise-client-urls=https://192.168.100.20:2379 \
--initial-cluster-token=etcd-cluster-0 \
--initial-cluster=master01=https://192.168.100.10:2380,master02=https://192.168.100.20:2380,master03=https://192.168.100.30:2380\
--initial-cluster-state=new \
--data-dir=/var/lib/etcd
Restart=on-failure
RestartSec=5
LimitNOFILE=65536
[Install]
WantedBy=multi-user.target

Start etcd service


# systemctl daemon-reload && systemctl enable etcd && systemctl start etcd

On Mmaster03

Create file /etc/systemd/system/etcd.service with the following content


[Unit]
Description=Etcd Server
After=network.target
After=network-online.target
Wants=network-online.target
Documentation=https://github.com/coreos
[Service]
Type=notify
WorkingDirectory=/var/lib/etcd/
ExecStart=/usr/local/bin/etcd \
--name=master03 \
--cert-file=/etc/etcd/ssl/etcd.pem \
--key-file=/etc/etcd/ssl/etcd-key.pem \
--peer-cert-file=/etc/etcd/ssl/etcd.pem \
--peer-key-file=/etc/etcd/ssl/etcd-key.pem \
--trusted-ca-file=/etc/etcd/ssl/ca.pem \
--peer-trusted-ca-file=/etc/etcd/ssl/ca.pem \
--initial-advertise-peer-urls=https://192.168.100.30:2380 \
--listen-peer-urls=https://192.168.100.30:2380 \
--listen-client-urls=https://192.168.100.30:2379,http://127.0.0.1:2379 \
--advertise-client-urls=https://192.168.100.30:2379 \
--initial-cluster-token=etcd-cluster-0 \
--initial-cluster=master01=https://192.168.100.10:2380,master02=https://192.168.100.20:2380,master03=https://192.168.100.30:2380\
--initial-cluster-state=new \
--data-dir=/var/lib/etcd
Restart=on-failure
RestartSec=5
LimitNOFILE=65536
[Install]
WantedBy=multi-user.target

Start etcd service


# systemctl daemon-reload && systemctl enable etcd && systemctl start etcd

Check ectd cluster status


# etcdctl --ca-file=/etc/etcd/ssl/ca.pem --cert-file=/etc/etcd/ssl/etcd.pem --key-file=/etc/etcd/ssl/etcd-key.pem cluster-health

Install Keepalived on All Master Nodes

The keepalived configuration file is located at /etc/keepalived/keepalived.conf. In this file , you need to replace KEEPALIVED_AUTH_PASS with your own password and make the password identical on all Master nodes, and change the interface item value to the server’s proper network interface name.

On Master01

Install keepalived


# yum install keepalived -y

Create keepalived configu file /etc/keepalived/keepalived.conf with the following content


global_defs {
   router_id LVS_k8s
}
vrrp_script CheckK8sMaster {
    script "curl -k https://192.168.100.10:6443"
    interval 3
    timeout 9
    fall 2
    rise 2
}
vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 61
    priority 80
    advert_int 1
    mcast_src_ip 192.168.100.10
    nopreempt
    authentication {
          auth_type PASS
        auth_pass KEEPALIVED_AUTH_PASS
    }
    unicast_peer {
        192.168.100.20
        192.168.100.30
    }
    virtual_ipaddress {
        192.168.100.60/24
    }
    track_script {
        CheckK8sMaster
    }
}

Start keepalived


systemctl daemon-reload && systemctl enable keepalived && systemctl restart keepalived

On Master02

Install keepalived


# yum install keepalived -y

Modify /etc/keepalived/keepalived.conf file to contain the following content


global_defs {
   router_id LVS_k8s
}
vrrp_script CheckK8sMaster {
    script "curl -k https://192.168.100.20:6443"
    interval 3
    timeout 9
    fall 2
    rise 2
}
vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 61
    priority 80
    advert_int 1
    mcast_src_ip 192.168.100.20
    nopreempt
    authentication {
        auth_type PASS
        auth_pass  KEEPALIVED_AUTH_PASS
    }
    unicast_peer {
        192.168.100.10
        192.168.100.30
    }
    virtual_ipaddress {
        192.168.100.60/24
    }
    track_script {
        CheckK8sMaster
    }
}

Start keepalived


# systemctl daemon-reload && systemctl enable keepalived && systemctl restart keepalived

On Master03

Install keepalived


# yum install keepalived -y

Create keepalived configuration file /etc/keepalived/keepalived.conf with the following content


global_defs {
   router_id LVS_k8s
}
vrrp_script CheckK8sMaster {
    script "curl -k https://192.168.100.30:6443"
    interval 3
    timeout 9
    fall 2
    rise 2
}
    vrrp_instance VI_1 {
    state BACKUP
    interface eth0
    virtual_router_id 61
    priority 80
    advert_int 1
    mcast_src_ip 192.168.100.30
    nopreempt
    authentication {
        auth_type PASS
        auth_pass KEEPALIVED_AUTH_PASS
    }
    unicast_peer {
        192.168.100.10
        192.168.100.20
    }
    virtual_ipaddress {
        192.168.100.60/24
    }
    track_script {
        CheckK8sMaster
    }
}

Start keepalived


# systemctl daemon-reload && systemctl enable keepalived && systemctl restart keepalived

Initiating Master Cluster

On Master01

Create file kubeadm-config.yaml with following content


apiVersion: kubeadm.k8s.io/v1alpha1
kind: MasterConfiguration
api:
  advertiseAddress: 192.168.100.10
etcd:
  endpoints:
  - https://192.168.100.10:2379
  - https://192.168.100.20:2379
  - https://192.168.100.30:2379
  caFile: /etc/etcd/ssl/ca.pem
  certFile: /etc/etcd/ssl/etcd.pem
  keyFile: /etc/etcd/ssl/etcd-key.pem
networking:
  podSubnet: 10.244.0.0/16
apiServerCertSANs:
- 192.168.100.10
- 192.168.100.20
- 192.168.100.30
- 192.168.100.60
apiServerExtraArgs:
  endpoint-reconciler-type: lease


Run the following command to initiate Kubernetes Master services


    # kubeadm init --config kubeadm-config.yaml

Copy pki files to all other master nodes


# scp -rp /etc/kubernetes/pki 192.168.100.20:/etc/kubernetes/
# scp -rp /etc/kubernetes/pki 192.168.100.30:/etc/kubernetes/

On Master02

Create file kubeadm-config.yaml with following content


apiVersion: kubeadm.k8s.io/v1alpha1
kind: MasterConfiguration
api:
  advertiseAddress: 192.168.100.20
etcd:
  endpoints:
  - https://192.168.100.10:2379
  - https://192.168.100.20:2379
  - https://192.168.100.30:2379
  caFile: /etc/etcd/ssl/ca.pem
  certFile: /etc/etcd/ssl/etcd.pem
  keyFile: /etc/etcd/ssl/etcd-key.pem
networking:
  podSubnet: 10.244.0.0/16
apiServerCertSANs:
- 192.168.100.10
- 192.168.100.20
- 192.168.100.30
- 192.168.100.60
apiServerExtraArgs:
  endpoint-reconciler-type: lease

Run the following command to initiate Kubernetes Master services


# kubeadm init --config kubeadm-config.yaml

On Master03

Create file kubeadm-config.yaml with following content


apiVersion: kubeadm.k8s.io/v1alpha1
kind: MasterConfiguration
api:
  advertiseAddress: 192.168.100.30
etcd:
  endpoints:
  - https://192.168.100.10:2379
  - https://192.168.100.20:2379
  - https://192.168.100.30:2379
  caFile: /etc/etcd/ssl/ca.pem
  certFile: /etc/etcd/ssl/etcd.pem
  keyFile: /etc/etcd/ssl/etcd-key.pem
networking:
  podSubnet: 10.244.0.0/16
apiServerCertSANs:
- 192.168.100.10
- 192.168.100.20
- 192.168.100.30
- 192.168.100.60
apiServerExtraArgs:
  endpoint-reconciler-type: lease

Run the following command to initiate Kubernetes Master services


# kubeadm init --config kubeadm-config.yaml

Configure Kuberctl on All Master Nodes

Execute the following command on all Master nodes


# mkdir -p /root/.kube
# cp -i /etc/kubernetes/admin.conf /root/.kube/config

Configure POD networking

On one of the masters run the following command:


# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/v0.10.0/Documentation/kube-flannel.yml

Joining Worker Nodes

Thanks for kubeadm, joining a Kubernetes worker node is as simple as running a command in console. The command line with the parameters and their value is what ‘kubeadm init’ execution returned in the previous step. You merely need to copy the command line and execute it on target servers.

Installing Other Supporting Components/Systems

Installing Kubernetes Dashboard

Create file dashboard.yaml with the following content


kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: ui-anonymous
rules:
- apiGroups:
  - ""
  resources:
  - services
  - services/proxy
  verbs:
  - '*'
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: ui-anonymous-binding
  namespace: kube-system
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: ui-anonymous
subjects:
- apiGroup: rbac.authorization.k8s.io
  kind: User
  name: system:anonymous
# ------------------- Dashboard Secret ------------------- #
---
apiVersion: v1
kind: Secret
metadata:
  labels:
    k8s-app: kubernetes-dashboard
  name: kubernetes-dashboard-certs
  namespace: kube-system
type: Opaque
---
# ------------------- Dashboard Service Account ------------------- #
apiVersion: v1
kind: ServiceAccount
metadata:
  labels:
    k8s-app: kubernetes-dashboard
  name: kubernetes-dashboard
  namespace: kube-system
---
# ------------------- Kubernetes-dashboard Clusterrolebind------------#
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
  name: kubernetes-dashboard
  labels:
    k8s-app: kubernetes-dashboard
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
- kind: ServiceAccount
  name: kubernetes-dashboard
  namespace: kube-system
---
# ------------------- Dashboard Role & Role Binding ------------------- #
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: kubernetes-dashboard-minimal
  namespace: kube-system
rules:
  # Allow Dashboard to create 'kubernetes-dashboard-key-holder' secret.
- apiGroups: [""]
  resources: ["secrets"]
  verbs: ["create"]
  # Allow Dashboard to create 'kubernetes-dashboard-settings' config map.
- apiGroups: [""]
  resources: ["configmaps"]
  verbs: ["create"]
  # Allow Dashboard to get, update and delete Dashboard exclusive secrets.
- apiGroups: [""]
  resources: ["secrets"]
  resourceNames: ["kubernetes-dashboard-key-holder", "kubernetes-dashboard-certs"]
  verbs: ["get", "update", "delete"]
  # Allow Dashboard to get and update 'kubernetes-dashboard-settings' config map.
- apiGroups: [""]
  resources: ["configmaps"]
  resourceNames: ["kubernetes-dashboard-settings"]
  verbs: ["get", "update"]
  # Allow Dashboard to get metrics from heapster.
- apiGroups: [""]
  resources: ["services"]
  resourceNames: ["heapster"]
  verbs: ["proxy"]
- apiGroups: [""]
  resources: ["services/proxy"]
  resourceNames: ["heapster", "http:heapster:", "https:heapster:"]
  verbs: ["get"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: kubernetes-dashboard-minimal
  namespace: kube-system
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: kubernetes-dashboard-minimal
subjects:
- kind: ServiceAccount
  name: kubernetes-dashboard
  namespace: kube-system
---
# ------------------- Dashboard Deployment ------------------- #
kind: Deployment
apiVersion: apps/v1beta2
metadata:
  labels:
    k8s-app: kubernetes-dashboard
  name: kubernetes-dashboard
  namespace: kube-system
spec:
  replicas: 1
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      k8s-app: kubernetes-dashboard
  template:
    metadata:
      labels:
        k8s-app: kubernetes-dashboard
    spec:
      containers:
       - name: kubernetes-dashboard
        image: k8s.gcr.io/kubernetes-dashboard-amd64:v1.8.3
        ports:
        - containerPort: 8443
          protocol: TCP
        args:
          - --auto-generate-certificates
          # Uncomment the following line to manually specify Kubernetes API server Host
          # If not specified, Dashboard will attempt to auto discover the API server and connect
          # to it. Uncomment only if the default does not work.
          # - --apiserver-host=http://my-address:port
        volumeMounts:
        - name: kubernetes-dashboard-certs
          mountPath: /certs
          # Create on-disk volume to store exec logs
        - mountPath: /tmp
          name: tmp-volume
        livenessProbe:
          httpGet:
            scheme: HTTPS
            path: /
            port: 8443
          initialDelaySeconds: 30
          timeoutSeconds: 30
      volumes:
      - name: kubernetes-dashboard-certs
        secret:
          secretName: kubernetes-dashboard-certs
      - name: tmp-volume
        emptyDir: {}
      serviceAccountName: kubernetes-dashboard
      # Comment the following tolerations if Dashboard must not be deployed on master
      tolerations:
      - key: node-role.kubernetes.io/master
        effect: NoSchedule
---
# ------------------- Dashboard Service ------------------- #
kind: Service
apiVersion: v1
metadata:
  labels:
    k8s-app: kubernetes-dashboard
  name: kubernetes-dashboard
 namespace: kube-system
spec:
  ports:
    - port: 443
      targetPort: 8443
  selector:
k8s-app: kubernetes-dashboard

Execute the following command in console


# kubectl create -f dashboard.yaml

Installing Helm

The installation can be done on any Master node

Create file helm-rbac.yaml as helm RBAC file with following content


apiVersion: v1
kind: ServiceAccount
metadata:
  name: tiller
  namespace: kube-system
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: tiller-cb
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
  - kind: ServiceAccount
    name: tiller
namespace: kube-system

Exec the following command


# kubectl create -f helm-rbac.yaml
# wget https://storage.googleapis.com/kubernetes-helm/helm-v2.9.1-linux-amd64.tar.gz
# tar -zxvf helm-v2.9.1-linux-amd64.tar.gz
# cp linux-amd64/helm /usr/local/bin/

# yum install socat -y
# helm init --service-account tiller --tiller-namespace kube-system

Verifying Cluster

Check Kubernetes version


# kubectl version

how-to-deploy-a-highly-available-kubernetes-cluster-with-kubeadm-on-CentOS7

Check Kubernetes components status


# kubectl get componentstatus 

how-to-deploy-a-highly-available-kubernetes-cluster-with-kubeadm-on-CentOS7

Check the node status


# kubectl get node

how-to-deploy-a-highly-available-kubernetes-cluster-with-kubeadm-on-CentOS7
Login to the Kubernetes dashboard

Open https://192.168.100.60:6443/api/v1/namespaces/kube-system/services/https:kubernetes-dashboard:/proxy in your browser and select Token option

how-to-deploy-a-highly-available-kubernetes-cluster-with-kubeadm-on-CentOS7

Retrieve dashboard token by running following command on one of Master nodes.


# Dashboard_Secret=`kubectl get secret -n kube-system|grep kubernetes-dashboard-token|awk '{print $1}'`
# kubectl describe secret -n kube-system ${Dashboard_Secret} |sed -n '$p'|awk '{print $NF}'

how-to-deploy-a-highly-available-kubernetes-cluster-with-kubeadm-on-CentOS7
how-to-deploy-a-highly-available-kubernetes-cluster-with-kubeadm-on-CentOS7

Congratulations!

Now you have a full-function working Kubernetes cluster. You can explore our other solutions if you want to know more.

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CPUs : Dual E5-2670
RAM : 128GB
Disks : 120GB SSD + 960GB SSD + 2TB SATA
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8 Bare-Metal Servers
Master Servers : 3
CPU : Intel E3-1230
RAM : 16GB
High Availability :
Node Servers : 5
CPUs : Dual E5-2670
RAM : 128GB
Disks : 120GB SSD + 960GB SSD + 2TB SATA
$872.00 / Month

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