kubeadm安装k8s集群

系统配置

在安装之前，需要先做如下准备。两台CentOS 7.4主机如下：

cat /etc/hosts
192.168.61.11 node1
192.168.61.12 node2

如果各个主机启用了防火墙，需要开放Kubernetes各个组件所需要的端口，可以查看Installing kubeadm中的"Check required ports"一节。 这里简单起见在各节点禁用防火墙：

systemctl stop firewalld
systemctl disable firewalld

禁用SELINUX：

setenforce 0 && sed -i 's/^SELINUX=.*/SELINUX=disabled/' /etc/selinux/config

禁用swap分区

swapoff -a && sed -i '/ swap / s/^(.*)$/#1/g' /etc/fstab 

加载模块

cat > /etc/sysconfig/modules/ipvs.modules <<EOF
#!/bin/bash
modprobe -- ip_vs
modprobe -- ip_vs_rr
modprobe -- ip_vs_wrr
modprobe -- ip_vs_sh
modprobe -- nf_conntrack_ipv4
EOF
chmod 755 /etc/sysconfig/modules/ipvs.modules && bash /etc/sysconfig/modules/ipvs.modules && lsmod | grep -e ip_vs -e nf_conntrack_ipv4

创建/etc/sysctl.d/k8s.conf文件，添加如下内容：

 cat > /etc/sysctl.d/k8s.conf <<EOF
net.bridge.bridge-nf-call-iptables=1 
net.bridge.bridge-nf-call-ip6tables=1 
net.ipv4.ip_forward=1 
net.ipv4.tcp_tw_recycle=0

vm.swappiness=0 # 禁止使用 swap 空间，只有当系统 OOM 时才允许使用它 
vm.overcommit_memory=1 # 不检查物理内存是否够用

vm.panic_on_oom=0 # 开启 OOM 
fs.inotify.max_user_instances=8192 
fs.inotify.max_user_watches=1048576 
fs.file-max=52706963 
fs.nr_open=52706963 
net.ipv6.conf.all.disable_ipv6=1 
net.netfilter.nf_conntrack_max=2310720

EOF

#生效
sysctl -p /etc/sysctl.d/k8s.conf

安装插件

yum install ipset ipvsadm conntrack-tools.x86_64 -y

安装docker

yum install -y yum-utils device-mapper-persistent-data lvm2
yum-config-manager 
    --add-repo 
    https://download.docker.com/linux/centos/docker-ce.repo

yum install -y --setopt=obsoletes=0 
  docker-ce

systemctl start docker
systemctl enable docker

使用kubeadm部署kubernetes

下面在各个节点安装kubeadm和kubelet

cat <<EOF > /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 -y install kubelet kubeadm kubectl

systemctl enable kubelet.service

安装所需镜像

下面在各个节点安装所需要的的镜像

for i in `kubeadm config images list`; do   
    imageName=${i#k8s.gcr.io/}  
    docker pull registry.aliyuncs.com/google_containers/$imageName      
    docker tag registry.aliyuncs.com/google_containers/$imageName k8s.gcr.io/$imageName  
    docker rmi registry.aliyuncs.com/google_containers/$imageName
done

使用kubeadm init初始化集群

在master节点操作

kubeadm init  
--kubernetes-version=v1.12.0  
--pod-network-cidr=10.244.0.0/16  
--apiserver-advertise-address=192.168.61.11 
--ignore-preflight-errors=Swap

[init] using Kubernetes version: v1.12.0
[preflight] running pre-flight checks
        [WARNING Swap]: running with swap on is not supported. Please disable swap
[preflight/images] Pulling images required for setting up a Kubernetes cluster
[preflight/images] This might take a minute or two, depending on the speed of your internet connection
[preflight/images] You can also perform this action in beforehand using 'kubeadm config images pull'
[kubelet] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[preflight] Activating the kubelet service
[certificates] Generated etcd/ca certificate and key.
[certificates] Generated etcd/peer certificate and key.
[certificates] etcd/peer serving cert is signed for DNS names [node1 localhost] and IPs [192.168.61.11 127.0.0.1 ::1]
[certificates] Generated apiserver-etcd-client certificate and key.
[certificates] Generated etcd/server certificate and key.
[certificates] etcd/server serving cert is signed for DNS names [node1 localhost] and IPs [127.0.0.1 ::1]
[certificates] Generated etcd/healthcheck-client certificate and key.
[certificates] Generated ca certificate and key.
[certificates] Generated apiserver certificate and key.
[certificates] apiserver serving cert is signed for DNS names [node1 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.61.11]
[certificates] Generated apiserver-kubelet-client certificate and key.
[certificates] Generated front-proxy-ca certificate and key.
[certificates] Generated front-proxy-client certificate and key.
[certificates] valid certificates and keys now exist in "/etc/kubernetes/pki"
[certificates] Generated sa key and public key.
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/admin.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/kubelet.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/controller-manager.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/scheduler.conf"
[controlplane] wrote Static Pod manifest for component kube-apiserver to "/etc/kubernetes/manifests/kube-apiserver.yaml"
[controlplane] wrote Static Pod manifest for component kube-controller-manager to "/etc/kubernetes/manifests/kube-controller-manager.yaml"
[controlplane] wrote Static Pod manifest for component kube-scheduler to "/etc/kubernetes/manifests/kube-scheduler.yaml"
[etcd] Wrote Static Pod manifest for a local etcd instance to "/etc/kubernetes/manifests/etcd.yaml"
[init] waiting for the kubelet to boot up the control plane as Static Pods from directory "/etc/kubernetes/manifests"
[init] this might take a minute or longer if the control plane images have to be pulled
[apiclient] All control plane components are healthy after 26.503672 seconds
[uploadconfig] storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.12" in namespace kube-system with the configuration for the kubelets in the cluster
[markmaster] Marking the node node1 as master by adding the label "node-role.kubernetes.io/master=''"
[markmaster] Marking the node node1 as master by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[patchnode] Uploading the CRI Socket information "/var/run/dockershim.sock" to the Node API object "node1" as an annotation
[bootstraptoken] using token: zalj3i.q831ehufqb98d1ic
[bootstraptoken] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstraptoken] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstraptoken] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstraptoken] creating the "cluster-info" ConfigMap in the "kube-public" namespace
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy

Your Kubernetes master 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/

You can now join any number of machines by running the following on each node
as root:

  kubeadm join 192.168.61.11:6443 --token zalj3i.q831ehufqb98d1ic --discovery-token-ca-cert-hash sha256:6ee48b19ba61a2dda77f6b60687c5fd11072ab898cfdfef32a68821d1dbe8efa

• [kubelet] 生成kubelet的配置文件"/var/lib/kubelet/config.yaml"
• [certificates]生成相关的各种证书
• [kubeconfig]生成相关的kubeconfig文件
• [bootstraptoken]生成token记录下来，后边使用kubeadm join往集群中添加节点时会用到
• 下面的命令是配置常规用户如何使用kubectl访问集群：

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

在node节点操作

 kubeadm join 192.168.61.11:6443 --token zalj3i.q831ehufqb98d1ic --discovery-token-ca-cert-hash sha256:6ee48b19ba61a2dda77f6b60687c5fd11072ab898cfdfef32a68821d1dbe8efa

安装Pod Network

mkdir -p ~/k8s/
cd ~/k8s
wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
kubectl apply -f  kube-flannel.yml

clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
serviceaccount/flannel created
configmap/kube-flannel-cfg created
daemonset.extensions/kube-flannel-ds-amd64 created
daemonset.extensions/kube-flannel-ds-arm64 created
daemonset.extensions/kube-flannel-ds-arm created
daemonset.extensions/kube-flannel-ds-ppc64le created
daemonset.extensions/kube-flannel-ds-s390x created

查看一下集群状态确认各个组件正常

kubectl get cs
NAME                 STATUS    MESSAGE              ERROR
controller-manager   Healthy   ok
scheduler            Healthy   ok
etcd-0               Healthy   {"health": "true"}

在slave节点操作

kubeadm join 192.168.61.11:6443 
--token zalj3i.q831ehufqb98d1ic 
--discovery-token-ca-cert-hash sha256:6ee48b19ba61a2dda77f6b60687c5fd11072ab898cfdfef32a68821d1dbe8efa 
--ignore-preflight-errors=Swap

集群初始化如果遇到问题，可以使用下面的命令进行清理：

kubeadm reset
ifconfig cni0 down
ip link delete cni0
ifconfig flannel.1 down
ip link delete flannel.1
rm -rf /var/lib/cni/