使用kubeadm方式搭建kubernetes集群
使用kubeadm方式搭建kubernetes集群
kubeadm
Kubeadm是一个K8s部署工具，提供kubeadm init 和kebuadm join,用于快速部署Kubernetes集群。可以通过两条指令完成一个Kubernetes集群的部署：
- 使用kubeadm init 创建一个Master节点
- 使用kubeadm join <Master节点IP和端口>将Node节点加入到当前集群中
最终目标
- 在所有节点安装Docker和kubeadm，kubelet,kubectl
- 部署Kubernetes Master
- 部署容器网络插件
- 部署Kubernetes Node，将节点加入Kubernetes集群
- 部署Dashboard Web页面，可视化查看Kubernetes资源
环境准备
| 角色 | IP |
|---|---|
| k8s-master | 192.168.1.16 |
| k8s-node1 | 192.168.1.30 |
| k8s-node2 | 192.168.1.31 |
安装
系统初始化
关闭防火墙
systemctl stop firewalld
systemctl disable firewalld
关闭selinux
sed -i 's/enforcing/disabled/' /etc/selinux/config && setenforce 0
关闭swap
# 临时关闭
swapoff -a
# 永久关闭，下次生效
sed -ri 's/.*swap.*/#&/' /etc/fstab
主机名
hostnamectl set-hostname <hostname>
在master添加hosts
cat >> /etc/hosts << EOF
192.168.1.16 k8s-master
192.168.1.30 k8s-node1
192.168.1.31 k8s-node2
EOF
将桥接的IPv4流量传递到iptables的链
cat > /etc/sysctl.d/k8s.conf << EOF
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF
# 生效
sysctl --system
时间同步
yum install ntpdate -y
ntpdate time.windows.com
所有节点安装Docker/kubeadm/kubelet/kubectl
安装docker
wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo -O /etc/yum.repos.d/docker-ce.repo
yum -y install docker-ce-18.06.1.ce-3.e17
systemctl enable docker && systemctl start docker
docker --version
添加阿里云YUM软件源
设置仓库地址
cat > /etc/docker/daemon.json << EOF
{
"registry-mirrors": ["https://b9pmyelo.mirror.aliyuncs.com"]
}
EOF
向/etc/yum.repos.d/kubernetes.repo添加yum源
[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
repo_gpgcheck=0
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg
https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
安装kubeadm，kubelet，kubectl
yum install -y kubelet kubeadm kubectl
systemctl enable kubelet
部署Kubernetes Master
kubeadm init \
--apiserver-advertise-address=192.168.1.16 \
--image-repository registry.aliyuncs.com/google_containers \
--kubernetes-version v1.23.1 \
--service-cidr=10.96.0.0/12 \
--pod-network-cidr=10.244.0.0/16
参数说明：
–kubernetes-version v1.23.1 指定版本
–apiserver-advertise-address 为通告给其它组件的IP，一般应为master节点的IP地址
–service-cidr 指定service网络，不能和node网络冲突
–pod-network-cidr 指定pod网络，不能和node网络、service网络冲突
–image-repository registry.aliyuncs.com/google_containers 指定镜像源，由于默认拉取镜像地址k8s.gcr.io国内无法访问，这里指定阿里云镜像仓库地址。
如果k8s版本比较新，可能阿里云没有对应的镜像，就需要自己从其它地方获取镜像了。
配置kubectl
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
查看节点信息
kubectl get nodes
配置flannel
创建配置文件：
vim kube-flannel.yml
---
apiVersion: policy/v1beta1
kind: PodSecurityPolicy
metadata:
name: psp.flannel.unprivileged
annotations:
seccomp.security.alpha.kubernetes.io/allowedProfileNames: docker/default
seccomp.security.alpha.kubernetes.io/defaultProfileName: docker/default
apparmor.security.beta.kubernetes.io/allowedProfileNames: runtime/default
apparmor.security.beta.kubernetes.io/defaultProfileName: runtime/default
spec:
privileged: false
volumes:
- configMap
- secret
- emptyDir
- hostPath
allowedHostPaths:
- pathPrefix: "/etc/cni/net.d"
- pathPrefix: "/etc/kube-flannel"
- pathPrefix: "/run/flannel"
readOnlyRootFilesystem: false
# Users and groups
runAsUser:
rule: RunAsAny
supplementalGroups:
rule: RunAsAny
fsGroup:
rule: RunAsAny
# Privilege Escalation
allowPrivilegeEscalation: false
defaultAllowPrivilegeEscalation: false
# Capabilities
allowedCapabilities: ['NET_ADMIN', 'NET_RAW']
defaultAddCapabilities: []
requiredDropCapabilities: []
# Host namespaces
hostPID: false
hostIPC: false
hostNetwork: true
hostPorts:
- min: 0
max: 65535
# SELinux
seLinux:
# SELinux is unused in CaaSP
rule: 'RunAsAny'
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: flannel
rules:
- apiGroups: ['extensions']
resources: ['podsecuritypolicies']
verbs: ['use']
resourceNames: ['psp.flannel.unprivileged']
- apiGroups:
- ""
resources:
- pods
verbs:
- get
- apiGroups:
- ""
resources:
- nodes
verbs:
- list
- watch
- apiGroups:
- ""
resources:
- nodes/status
verbs:
- patch
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: flannel
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: flannel
subjects:
- kind: ServiceAccount
name: flannel
namespace: kube-system
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: flannel
namespace: kube-system
---
kind: ConfigMap
apiVersion: v1
metadata:
name: kube-flannel-cfg
namespace: kube-system
labels:
tier: node
app: flannel
data:
cni-conf.json: |
{
"name": "cbr0",
"cniVersion": "0.3.1",
"plugins": [
{
"type": "flannel",
"delegate": {
"hairpinMode": true,
"isDefaultGateway": true
}
},
{
"type": "portmap",
"capabilities": {
"portMappings": true
}
}
]
}
net-conf.json: |
{
"Network": "10.245.0.0/16",
"Backend": {
"Type": "vxlan"
}
}
---
apiVersion: apps/v1
kind: DaemonSet
metadata:
name: kube-flannel-ds
namespace: kube-system
labels:
tier: node
app: flannel
spec:
selector:
matchLabels:
app: flannel
template:
metadata:
labels:
tier: node
app: flannel
spec:
affinity:
nodeAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
nodeSelectorTerms:
- matchExpressions:
- key: kubernetes.io/os
operator: In
values:
- linux
hostNetwork: true
priorityClassName: system-node-critical
tolerations:
- operator: Exists
effect: NoSchedule
serviceAccountName: flannel
initContainers:
- name: install-cni
image: quay.io/coreos/flannel:v0.14.0
command:
- cp
args:
- -f
- /etc/kube-flannel/cni-conf.json
- /etc/cni/net.d/10-flannel.conflist
volumeMounts:
- name: cni
mountPath: /etc/cni/net.d
- name: flannel-cfg
mountPath: /etc/kube-flannel/
containers:
- name: kube-flannel
image: quay.io/coreos/flannel:v0.14.0
command:
- /opt/bin/flanneld
args:
- --ip-masq
- --kube-subnet-mgr
resources:
requests:
cpu: "100m"
memory: "50Mi"
limits:
cpu: "100m"
memory: "50Mi"
securityContext:
privileged: false
capabilities:
add: ["NET_ADMIN", "NET_RAW"]
env:
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
volumeMounts:
- name: run
mountPath: /run/flannel
- name: flannel-cfg
mountPath: /etc/kube-flannel/
volumes:
- name: run
hostPath:
path: /run/flannel
- name: cni
hostPath:
path: /etc/cni/net.d
- name: flannel-cfg
configMap:
name: kube-flannel-cfg
执行yaml文件：
kubectl apply -f kube-flannel.yml
查看flannel部署结果：
kubectl -n kube-system get pods -o wide
查看node状态：
kubectl get nodes
部署Kubernetes Node
在192.168.1.30跟192.168.1.31上向集群添加新节点，执行在kubeadm init输出的kubeadm join命令:
kubeadm join 192.168.1.16:6443 --token smmkaf.f9mft92fmix6dwby \
--discovery-token-ca-cert-hash sha256:5ee2a223c8151b27efb73783b4df000aa23532964f77e86e2d25fb826748da28
测试Kubernetes集群
在Kubernetes中创建一个Pod，验证是否正常运行：
kubectl create deployment nginx --image=nginx
kubectl expose deployment nginx --port 80 --type NodePort
kubectl get pod,svc
访问地址：http://NodeIP:Port
安装过程出现的问题
升级系统内核
CentOS 7.x 系统自带的 3.10.x 内核存在一些 Bugs，导致运行的 Docker、Kubernetes 不稳定。
CentOS 允许使用 ELRepo，这是一个第三方仓库，可以将内核升级到最新版本。
要在 CentOS 7 上启用 ELRepo 仓库，请运行：
rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
rpm -Uvh http://www.elrepo.org/elrepo-release-7.0-2.el7.elrepo.noarch.rpm
仓库启用后，你可以使用下面的命令列出可用的内核相关包：
yum --disablerepo="*" --enablerepo="elrepo-kernel" list available
安装最新的主线稳定内核：
yum --enablerepo=elrepo-kernel install kernel-ml
最后，重启机器并应用最新内核，接着运行下面的命令检查最新内核版本：
curl: Peer reports incompatible or unsupported protocol version
查找原因是curl,nss版本低的原因，解决办法就是更新nss,curl。
yum update nss curl
初始化 Kubernetes 问题（配置文件已存在）
kubeadm reset
初始化 Kubernetes 问题（failed to run Kubelet: misconfiguration: kubelet cgroup driver: “cgroupfs” is different from docker cgroup driver: “systemd” ）
初始化失败，提示kubelet 健康状态不正常。
查看 kubelet 状态 systemctl status kubelet，提示error: failed to run Kubelet: failed to create kubelet: misconfiguration: kubelet cgroup driver: “systemd” is different from docker cgroup driver: “cgroupfs”。
修改docker，只需在/etc/docker/daemon.json中，添加"exec-opts": [“native.cgroupdriver=systemd”]即可
{
"registry-mirrors":["https://docker.mirrors.ustc.edu.cn"],
"exec-opts": ["native.cgroupdriver=systemd"]
}
修改kubelet：
cat > /var/lib/kubelet/config.yaml <<EOF
apiVersion: kubelet.config.k8s.io/v1beta1
kind: KubeletConfiguration
cgroupDriver: systemd
EOF
重启docker 与 kubelet:
systemctl daemon-reload
systemctl restart docker
systemctl restart kubelet
检查 docker info|grep “Cgroup Driver” 是否输出 Cgroup Driver: systemd:
