k8s集群环境搭建（一主二从--kubeadm安装）

前置条件

版本：CentOS Linux release 7.5.1804 (Core)

内存：2G

CPU：2

主机名解析
vim /etc/hosts
192.168.109.100 master
192.168.109.101 node1
192.168.109.102 node2


时间同步，这里直接使用chronyd服务从网络同步时间

systemctl start chronyd
systemctl enable chronyd
date
#查看时间是否同步


禁用iptables和firewalld服务
#关闭防火墙和iptables
systemctl stop firewalld
systemctl disabled firewalld

systemctl stop iptables
systemctl disabled iptables

禁用selinux
selinux是linux系统下的一个安全服务，如果不关闭它，在安装集群中会产生各种各样的奇葩问题

~~~powershell
# 编辑 /etc/selinux/config 文件，修改SELINUX的值为disabled
# 注意修改完毕之后需要重启linux服务
vim /etc/selinux/config
SELINUX=disabled



禁用swap分区

# 编辑分区配置文件/etc/fstab，注释掉swap分区一行
# 注意修改完毕之后需要重启linux服务
 UUID=455cc753-7a60-4c17-a424-7741728c44a1 /boot    xfs     defaults        0 0
 /dev/mapper/centos-home /home                      xfs     defaults        0 0
# /dev/mapper/centos-swap swap                      swap    defaults        0 0



修改linux的内核参数

vim /etc/sysctl.d/kubernetes.conf

net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1


# 重新加载配置
sysctl -p
# 加载网桥过滤模块
modprobe br_netfilter
# 查看网桥过滤模块是否加载成功    
lsmod | grep br_netfilter




配置ipvs功能

在kubernetes中service有两种代理模型，一种是基于iptables的，一种是基于ipvs的

两者比较的话，ipvs的性能明显要高一些，但是如果要使用它，需要手动载入ipvs模块

~~~powershell
# 1 安装ipset和ipvsadm
[root@master ~]# yum install ipset ipvsadm -y

# 2 添加需要加载的模块写入脚本文件
cat <<EOF >  /etc/sysconfig/modules/ipvs.modules
#!/bin/bash
modprobe -- ip_vs
modprobe -- ip_vs_rr
modprobe -- ip_vs_wrr
modprobe -- ip_vs_sh
modprobe -- nf_conntrack_ipv4
EOF

# 3 为脚本文件添加执行权限
 chmod +x /etc/sysconfig/modules/ipvs.modules

# 4 执行脚本文件
 /bin/bash /etc/sysconfig/modules/ipvs.modules

# 5 查看对应的模块是否加载成功
lsmod | grep -e ip_vs -e nf_conntrack_ipv4



重启服务器
reboot

安装docker

切换镜像源

wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo -O /etc/yum.repos.d/docker-ce.repo

查看当前镜像源中支持的docker版本

yum list docker-ce --showduplicates

安装特定版本的docker-ce

#必须指定--setopt=obsoletes=0，否则yum会自动安装更高版本

yum install --setopt=obsoletes=0 docker-ce-18.06.3.ce-3.el7 -y

自己找一个上边列表中有的安装就行，这里以docker-ce-18.06.3.ce-3.el7为例

添加一个配置文件

Docker在默认情况下使用的Cgroup Driver为cgroupfs，而kubernetes推荐使用systemd来代替cgroupfs

mkdir /etc/docker
cat <<EOF >  /etc/docker/daemon.json
{
  "exec-opts": ["native.cgroupdriver=systemd"],
  "registry-mirrors": ["https://kn0t2bca.mirror.aliyuncs.com"]
}
EOF

启动docker

systemctl restart docker
systemctl enable docker

验证是否安装完成

docker version
docker ps -a

安装kubernetes组件

由于kubernetes的镜像源在国外，速度比较慢，这里切换成国内的镜像源

编辑/etc/yum.repos.d/kubernetes.repo，添加下面的配置

vim /etc/yum.repos.d/kubernetes.repo

[kubernetes]
name=Kubernetes
baseurl=http://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
repo_gpgcheck=0
gpgkey=http://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg
       http://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg

安装kubeadm、kubelet和kubectl

版本可以自定义，但需要保证三个主机的版本完全相同

 yum install --setopt=obsoletes=0 kubeadm-1.17.4-0 kubelet-1.17.4-0 kubectl-1.17.4-0 -y

配置kubelet的cgroup

编辑/etc/sysconfig/kubelet，添加下面的配置

vim /etc/sysconfig/kubelet

KUBELET_CGROUP_ARGS="--cgroup-driver=systemd"
KUBE_PROXY_MODE="ipvs"

设置kubelet开机自启

 systemctl enable kubelet

准备集群镜像

~~~powershell

在安装kubernetes集群之前，必须要提前准备好集群需要的镜像，所需镜像可以通过下面命令查看

kubeadm config images list

这个是建议的镜像版本，你出现多少版本就用多少，并按我下面这个格式修改版本

# 下载镜像
# 此镜像在kubernetes的仓库中,由于网络原因,无法连接，下面提供了一种替代方案

images=(
    kube-apiserver:v1.17.4
    kube-controller-manager:v1.17.4
    kube-scheduler:v1.17.4
    kube-proxy:v1.17.4
    pause:3.1
    etcd:3.4.3-0
    coredns:1.6.5
)

for imageName in ${images[@]} ; do
	docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/$imageName
	docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/$imageName 		k8s.gcr.io/$imageName
	docker rmi registry.cn-hangzhou.aliyuncs.com/google_containers/$imageName
done

下载卡住可重新执行for循环这段

集群初始化

下面开始对集群进行初始化，并将node节点加入到集群中

> 下面的操作只需要在`master`节点上执行即可

kubeadm init \
	--kubernetes-version=v1.17.4 \
    --pod-network-cidr=10.244.0.0/16 \
    --service-cidr=10.96.0.0/12 \
    --apiserver-advertise-address=192.168.109.100#ip改为你自己的masterip

# 创建必要文件
[root@master ~]# mkdir -p $HOME/.kube
[root@master ~]# sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
[root@master ~]# sudo chown $(id -u):$(id -g) $HOME/.kube/config
~~~

上述代码会在完成kubeadm init后自动弹出

> 下面的操作只需要在`node`节点上执行即可

将node节点加入集群

下边这段代码也在完成kubeadm init后自动弹出

kubeadm join 192.168.109.100:6443 \ 
	--token 8507uc.o0knircuri8etnw2 \
	--discovery-token-ca-cert-hash \
	sha256:acc37967fb5b0acf39d7598f8a439cc7dc88f439a3f4d0c9cae88e7901b9d3f

查看集群状态

查看集群状态 此时的集群状态为NotReady，这是因为还没有配置网络插件
[root@master ~]# kubectl get nodes
NAME     STATUS     ROLES    AGE     VERSION
master   NotReady   master   6m43s   v1.17.4
node1    NotReady   <none>   22s     v1.17.4
node2    NotReady   <none>   19s     v1.17.4

安装网络插件

kubernetes支持多种网络插件，比如flannel、calico、canal等等，任选一种使用即可，本次选择flannel

 wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

修改文件中quay.io仓库为quay-mirror.qiniu.com

使用配置文件启动fannel

kubectl apply -f kube-flannel.yml

# 稍等片刻，再次查看集群节点的状态
[root@master ~]# kubectl get nodes
NAME     STATUS   ROLES    AGE     VERSION
master   Ready    master   15m     v1.17.4
node1    Ready    <none>   8m53s   v1.17.4
node2    Ready    <none>   8m50s   v1.17.4

在此提供一个改好的yml,需要的话直接复制

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']
  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/v1beta1
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/v1beta1
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": "10.244.0.0/16",
      "Backend": {
        "Type": "vxlan"
      }
    }
---
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: kube-flannel-ds-amd64
  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: beta.kubernetes.io/os
                    operator: In
                    values:
                      - linux
                  - key: beta.kubernetes.io/arch
                    operator: In
                    values:
                      - amd64
      hostNetwork: true
      tolerations:
      - operator: Exists
        effect: NoSchedule
      serviceAccountName: flannel
      initContainers:
      - name: install-cni
        image: quay-mirror.qiniu.com/coreos/flannel:v0.12.0-amd64
        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-mirror.qiniu.com/coreos/flannel:v0.12.0-amd64
        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"]
        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
---
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: kube-flannel-ds-arm64
  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: beta.kubernetes.io/os
                    operator: In
                    values:
                      - linux
                  - key: beta.kubernetes.io/arch
                    operator: In
                    values:
                      - arm64
      hostNetwork: true
      tolerations:
      - operator: Exists
        effect: NoSchedule
      serviceAccountName: flannel
      initContainers:
      - name: install-cni
        image: quay-mirror.qiniu.com/coreos/flannel:v0.12.0-arm64
        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-mirror.qiniu.com/coreos/flannel:v0.12.0-arm64
        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"]
        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
---
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: kube-flannel-ds-arm
  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: beta.kubernetes.io/os
                    operator: In
                    values:
                      - linux
                  - key: beta.kubernetes.io/arch
                    operator: In
                    values:
                      - arm
      hostNetwork: true
      tolerations:
      - operator: Exists
        effect: NoSchedule
      serviceAccountName: flannel
      initContainers:
      - name: install-cni
        image: quay-mirror.qiniu.com/coreos/flannel:v0.12.0-arm
        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-mirror.qiniu.com/coreos/flannel:v0.12.0-arm
        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"]
        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
---
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: kube-flannel-ds-ppc64le
  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: beta.kubernetes.io/os
                    operator: In
                    values:
                      - linux
                  - key: beta.kubernetes.io/arch
                    operator: In
                    values:
                      - ppc64le
      hostNetwork: true
      tolerations:
      - operator: Exists
        effect: NoSchedule
      serviceAccountName: flannel
      initContainers:
      - name: install-cni
        image: quay-mirror.qiniu.com/coreos/flannel:v0.12.0-ppc64le
        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-mirror.qiniu.com/coreos/flannel:v0.12.0-ppc64le
        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"]
        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
---
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: kube-flannel-ds-s390x
  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: beta.kubernetes.io/os
                    operator: In
                    values:
                      - linux
                  - key: beta.kubernetes.io/arch
                    operator: In
                    values:
                      - s390x
      hostNetwork: true
      tolerations:
      - operator: Exists
        effect: NoSchedule
      serviceAccountName: flannel
      initContainers:
      - name: install-cni
        image: quay-mirror.qiniu.com/coreos/flannel:v0.12.0-s390x
        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-mirror.qiniu.com/coreos/flannel:v0.12.0-s390x
        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"]
        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

服务部署

接下来在kubernetes集群中部署一个nginx程序，测试下集群是否在正常工作。以部署nginx为例

# 部署nginx
 kubectl create deployment nginx --image=nginx:1.14-alpine

# 暴露端口
 kubectl expose deployment nginx --port=80 --type=NodePort

# 查看服务状态
[root@master ~]# kubectl get pods,service
NAME                         READY   STATUS    RESTARTS   AGE
pod/nginx-86c57db685-fdc2k   1/1     Running   0          18m

NAME                 TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
service/kubernetes   ClusterIP   10.96.0.1       <none>        443/TCP        82m
service/nginx        NodePort    10.104.121.45   <none>        80:30073/TCP   17m

成功