Introduction to Kubernetes
Kubernetes (K8S) is an open source container cluster management system, which can realize the functions of automatic deployment, automatic expansion and maintenance of container cluster. It is not only a container layout tool, but also a new distributed architecture leading scheme based on container technology. On the basis of Docker technology, it provides deployment and operation, resource scheduling, service discovery and dynamic scaling functions for container applications, which improves the convenience of large-scale container cluster management.
There are two types of K8S cluster: management node and working node. The management node is mainly responsible for K8S cluster management, information exchange and task scheduling among nodes in the cluster, and life cycle management of containers, Pod, NameSpaces, PV, etc. Work nodes mainly provide computing resources for containers and pods. Pod and containers all run on work nodes. Work nodes communicate with management nodes through kubelet services to manage the life cycle of containers and communicate with other nodes in the cluster.
Tip: master and open key login
ssh-keygen ssh-copy-id root@192.168.3.71 ssh-copy-id root@192.168.3.72
Installation Environment Configuration (Next step needs to be performed on all hosts)
1. Before installation, the following preparations should be made. Three CentOS 7 hosts are as follows (more or less can be determined by themselves, at least two or more):
Setting Host Names on Autonomous Machines
192.168.3.70
#hostnamectl set-hostname master
Or modify the configuration file to permanently modify your host name, and modify the file by following steps
cat >> /etc/sysconfig/network << EOF hostname=master EOF
2. Edit / etc/hosts file and add domain name resolution.
cat <<EOF >>/etc/hosts 192.168.3.70 master 192.168.3.71 node1 192.168.3.72 node2 EOF
3. Close firewalls, selinux and swap.
systemctl stop firewalld systemctl disable firewalld setenforce 0 sed -i "s/^SELINUX=enforcing/SELINUX=disabled/g" /etc/selinux/config swapoff -a sed -i 's/.*swap.*/#&/' /etc/fstab
4. The first installation opened the routing and forwarding function, many documents were not written, but I did report a mistake when I installed it.
echo "1" > /proc/sys/net/ipv4/ip_forward
5. Configure kernel parameters to transfer bridged IPv4 traffic to the chain of iptables
cat > /etc/sysctl.d/k8s.conf <<EOF
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF
Make it effective
sysctl --system
6. Configuring domestic yum sources
yum install -y wget mkdir /etc/yum.repos.d/bak && mv /etc/yum.repos.d/*.repo /etc/yum.repos.d/bak wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.cloud.tencent.com/repo/centos7_base.repo wget -O /etc/yum.repos.d/epel.repo http://mirrors.cloud.tencent.com/repo/epel-7.repo yum clean all && yum makecache
Configuration of domestic Kubernetes sources
cat <<EOF > /etc/yum.repos.d/kubernetes.repo [kubernetes] name=Kubernetes baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/ enabled=1 gpgcheck=1 repo_gpgcheck=1 gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg EOF
Configure docker source
wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo -O /etc/yum.repos.d/docker-ce.repo
3. Start installing docker, kubeadm, kubectl, kubelet
1. Install docker
yum install -y docker-ce-18.06.1.ce-3.el7 systemctl enable docker && systemctl start docker docker version
2. Install kubeadm, kubelet, kubectl
yum install -y kubelet kubeadm kubectl systemctl enable kubelet
IV. master Deployment
Tip: Execute on master node
1. Initialize Kubernetes cluster in master.
kubeadm init --kubernetes-version=1.15.0 --apiserver-advertise-address=192.168.3.70 --image-repository registry.aliyuncs.com/google_containers --service-cidr=10.1.0.0/16 --pod-network-cidr=10.244.0.0/16
apiserver-advertise-address=192.168.3.70 (master address)
Finally, token is generated as follows
kubeadm join 192.168.3.70:6443 --token kekvgu.nw1n76h84f4camj6 \ --discovery-token-ca-cert-hash sha256:4ee74205227c78ca62f2d641635afa4d50e6634acfaa8291f28582c7e3b0e30e
2. Configuring the kubectl tool
The system starts kubernetes from admin.conf file, and it won't work if it's not configured.
mkdir -p /root/.kube cp /etc/kubernetes/admin.conf /root/.kube/config
kubectl get nodes # Look at all the nodes in the cluster, and it's still not read because the flannel network has not been deployed yet.
3. Deployment of flannel network
kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/a70459be0084506e4ec919aa1c114638878db11b/Documentation/kube-flannel.yml
5. node deployment
Execute the token section we generated on master directly on each node
kubeadm join 192.168.3.70:6443 --token kekvgu.nw1n76h84f4camj6 \ --discovery-token-ca-cert-hash sha256:4ee74205227c78ca62f2d641635afa4d50e6634acfaa8291f28582c7e3b0e30e
At this point, the cluster deployment is complete and the status of nodes can be obtained on the master
kubectl get nodes -o wide
Explain the successful deployment for read.