使用kubeadm 安装 kubernetes 1.15.1

时间 2019-11-11

标签使用 kubeadm 安装 kubernetes 1.15.1 繁體版

原文原文链接

简介：

Kubernetes做为Google开源的容器运行平台，受到了你们的热捧。搭建一套完整的kubernetes平台，也成为试用这套平台必须迈过的坎儿。kubernetes1.5版本以及以前，安装仍是相对比较方便的，官方就有经过yum源在centos7安装kubernetes。可是在kubernetes1.6以后，安装就比较繁琐了，须要证书各类认证，对于刚接触kubernetes的人来讲很不友好。html

docker : kubernetes依赖的容器运行时
kubelet: kubernetes最核心的agent组件,每一个节点都会启动一个,负责像pods及节点的生命周期等管理
kubectl: kubernetes的命令行控制工具,只能够在master上使用.
kubeadm: 用来bootstrap kubernetes. 初始化一个k8s集群.

架构说明：

配置host

[root@master /]# cat /etc/hosts
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6

18.16.202.163  master
18.16.202.227 slaver1
18.16.202.95  slaver2

配置代理上网：

etc/profile文件内添加：node

export http_proxy="http://18.16.202.169:8118"
export https_proxy="https://18.16.202.169:8118"

printf -v no_ip_proxy '%s,' 18.16.202.{1..255};

export no_proxy=.baidu.com,.aliyun.com,.aliyuncs.com,.360doc.com,.163.com,.163yun.com,.tencent.com,qq.com,.daocloud.io,.cn,local,localhost,localdomain,127.0.0.1,"${no_ip_proxy%,}"

注意这里不能使用星号模糊匹配，Linux中不支持linux

ip_host="192.168.3.7:8118"
export http_proxy="http://${ip_host}"                                                     
export https_proxy="https://${ip_host}"

printf -v no_ip_proxy '%s,' 192.168.236.{1..255};

export no_proxy=.baidu.com,.aliyun.com,.aliyuncs.com,.360doc.com,.163.com,.163yun.com,.tencent.com,qq.com,.daocloud.io,.cn,local,localhost,localdomain,127.0.0.1,"${no_ip_proxy%,}"

若是要取消代理，能够直接命令设置：git

unset https_proxy
unset http_proxy

再次使用代理：github

source /etc/profile

全部节点前置配置:

关闭防火墙

systemctl stop firewalld
systemctl disable firewalld

iptables对bridge的数据进行处理:docker

建立/etc/sysctl.d/k8s.conf文件，添加以下内容：shell

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

执行命令使修改生效。json

modprobe br_netfilter
sysctl -p /etc/sysctl.d/k8s.conf

禁用SELinux

setenforce 0

编辑文件/etc/selinux/config，将SELINUX修改成disabled，以下：bootstrap

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

#SELINUX=disabled

关闭系统Swap

Kubernetes 1.8开始要求关闭系统的Swap，若是不关闭，默认配置下kubelet将没法启动。方法一,经过kubelet的启动参数–fail-swap-on=false更改这个限制。方法二,关闭系统的Swap。centos

swapoff -a

修改/etc/fstab文件，注释掉SWAP的自动挂载，使用free -m确认swap已经关闭。

#注释掉swap分区
[root@localhost /]# sed -i 's/.*swap.*/#&/' /etc/fstab

#/dev/mapper/centos-swap swap                    swap    defaults        0 0
                                                                
[root@localhost /]# free -m
              total        used        free      shared  buff/cache   available
Mem:            962         154         446           6         361         612
Swap:             0           0           0

永久禁用swap

echo "vm.swappiness = 0">> /etc/sysctl.conf

kube-proxy开启ipvs的前置条件

因为ipvs已经加入到了内核的主干，因此为kube-proxy开启ipvs的前提须要加载如下的内核模块：

ip_vs
ip_vs_rr
ip_vs_wrr
ip_vs_sh
nf_conntrack_ipv4

在全部的Kubernetes节点node1和node2上执行如下脚本:

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

上面脚本建立了的/etc/sysconfig/modules/ipvs.modules文件，保证在节点重启后能自动加载所需模块。使用lsmod | grep -e ip_vs -e nf_conntrack_ipv4命令查看是否已经正确加载所需的内核模块。

接下来还须要确保各个节点上已经安装了ipset软件包。

yum install -y ipset

为了便于查看ipvs的代理规则，最好安装一下管理工具ipvsadm 。

yum install -y ipvsadm

若是以上前提条件若是不知足，则即便kube-proxy的配置开启了ipvs模式，也会退回到iptables模式。

安装docker

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

查看最新docker版本：

[root@localhost /]# yum list docker-ce.x86_64  --showduplicates |sort -r
已加载插件：fastestmirror
可安装的软件包
 * updates: mirrors.aliyun.com
Loading mirror speeds from cached hostfile
 * extras: mirrors.aliyun.com
 * elrepo: mirrors.tuna.tsinghua.edu.cn
docker-ce.x86_64            3:19.03.0-3.el7                     docker-ce-stable
docker-ce.x86_64            3:18.09.8-3.el7                     docker-ce-stable
docker-ce.x86_64            3:18.09.7-3.el7                     docker-ce-stable
docker-ce.x86_64            3:18.09.6-3.el7                     docker-ce-stable
docker-ce.x86_64            3:18.09.5-3.el7                     docker-ce-stable
docker-ce.x86_64            3:18.09.4-3.el7                     docker-ce-stable
docker-ce.x86_64            3:18.09.3-3.el7                     docker-ce-stable
docker-ce.x86_64            3:18.09.2-3.el7                     docker-ce-stable
docker-ce.x86_64            3:18.09.1-3.el7                     docker-ce-stable
docker-ce.x86_64            3:18.09.0-3.el7                     docker-ce-stable
docker-ce.x86_64            18.06.3.ce-3.el7                    docker-ce-stable
docker-ce.x86_64            18.06.2.ce-3.el7                    docker-ce-stable
docker-ce.x86_64            18.06.1.ce-3.el7                    docker-ce-stable
docker-ce.x86_64            18.06.0.ce-3.el7                    docker-ce-stable
docker-ce.x86_64            18.03.1.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            18.03.0.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.12.1.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.12.0.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.09.1.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.09.0.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.06.2.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.06.1.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.06.0.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.03.3.ce-1.el7                    docker-ce-stable
docker-ce.x86_64            17.03.2.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.03.1.ce-1.el7.centos             docker-ce-stable
docker-ce.x86_64            17.03.0.ce-1.el7.centos             docker-ce-stable

安装docker:

# sudo yum -y install docker-ce
sudo yum install -y --setopt=obsoletes=0 docker-ce-18.09.8-3.el7 
systemctl enable docker.service
systemctl restart docker

我这里安装的是docker-ce 18.09

设置为开机启动：

[root@master /]# systemctl enable docker
Created symlink from /etc/systemd/system/multi-user.target.wants/docker.service to /usr/lib/systemd/system/docker.service.

修改docker cgroup driver为systemd

对于使用systemd做为init system的Linux的发行版，使用systemd做为docker的cgroup driver能够确保服务器节点在资源紧张的状况更加稳定，所以这里修改各个节点上docker的cgroup driver为systemd。

建立或修改/etc/docker/daemon.json：

{
  "registry-mirrors": ["https://tqvgn53t.mirror.aliyuncs.com"],
  "exec-opts": ["native.cgroupdriver=systemd"]
}

重启docker：

systemctl restart docker

docker info | grep Cgroup
Cgroup Driver: systemd

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

测试地址https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64是否可用。

curl https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64

安装:

yum makecache fast
yum install -y kubelet kubeadm kubectl

安装kubeadm init初始化集群所需docker镜像

开始初始化集群以前可使用kubeadm config images pull预先在各个节点上拉取所k8s须要的docker镜像

[root@localhost /]# kubeadm config images list
W0725 10:52:57.395062    8776 version.go:98] could not fetch a Kubernetes version from the internet: unable to get URL "https://dl.k8s.io/release/stable-1.txt": Get https://dl.k8s.io/release/stable-1.txt: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
W0725 10:52:57.395395    8776 version.go:99] falling back to the local client version: v1.15.1
k8s.gcr.io/kube-apiserver:v1.15.1
k8s.gcr.io/kube-controller-manager:v1.15.1
k8s.gcr.io/kube-scheduler:v1.15.1
k8s.gcr.io/kube-proxy:v1.15.1
k8s.gcr.io/pause:3.1
k8s.gcr.io/etcd:3.3.10
k8s.gcr.io/coredns:1.3.1
[root@localhost /]# kubeadm config images pull
W0725 10:55:12.586377    8781 version.go:98] could not fetch a Kubernetes version from the internet: unable to get URL "https://dl.k8s.io/release/stable-1.txt": Get https://dl.k8s.io/release/stable-1.txt: proxyconnect tcp: net/http: TLS handshake timeout
W0725 10:55:12.586550    8781 version.go:99] falling back to the local client version: v1.15.1

明显是网络问题，k8s.gcr.io 资源获取不了

在网上找了其余的资源，建立一个shell文件，粘贴运行

MY_REGISTRY=gcr.azk8s.cn/google-containers

## 拉取镜像
docker pull ${MY_REGISTRY}/kube-apiserver:v1.15.1
docker pull ${MY_REGISTRY}/kube-controller-manager:v1.15.1
docker pull ${MY_REGISTRY}/kube-scheduler:v1.15.1
docker pull ${MY_REGISTRY}/kube-proxy:v1.15.1
docker pull ${MY_REGISTRY}/pause:3.1
docker pull ${MY_REGISTRY}/etcd:3.3.10
docker pull ${MY_REGISTRY}/coredns:1.3.1

## 添加Tag
docker tag ${MY_REGISTRY}/kube-apiserver:v1.15.1 k8s.gcr.io/kube-apiserver:v1.15.1
docker tag ${MY_REGISTRY}/kube-controller-manager:v1.15.1 k8s.gcr.io/kube-controller-manager:v1.15.1
docker tag ${MY_REGISTRY}/kube-scheduler:v1.15.1 k8s.gcr.io/kube-scheduler:v1.15.1
docker tag ${MY_REGISTRY}/kube-proxy:v1.15.1 k8s.gcr.io/kube-proxy:v1.15.1
docker tag ${MY_REGISTRY}/pause:3.1 k8s.gcr.io/pause:3.1
docker tag ${MY_REGISTRY}/etcd:3.3.10 k8s.gcr.io/etcd:3.3.10
docker tag ${MY_REGISTRY}/coredns:1.3.1 k8s.gcr.io/coredns:1.3.1
 
#删除无用的镜像
docker images | grep ${MY_REGISTRY} | awk '{print "docker rmi "  $1":"$2}' | sh -x

echo "end"

上面的全部操做能够在一个节点上面完成，而后对进行复制便可。

集群操做

kubeadm初始化配置

使用kubeadm config print init-defaults能够打印集群初始化默认的使用的配置：

[root@localhost /]# kubeadm config print init-defaults
apiVersion: kubeadm.k8s.io/v1beta2
bootstrapTokens:
- groups:
  - system:bootstrappers:kubeadm:default-node-token
  token: abcdef.0123456789abcdef
  ttl: 24h0m0s
  usages:
  - signing
  - authentication
kind: InitConfiguration
localAPIEndpoint:
  advertiseAddress: 1.2.3.4
  bindPort: 6443
nodeRegistration:
  criSocket: /var/run/dockershim.sock
  name: localhost.localdomain
  taints:
  - effect: NoSchedule
    key: node-role.kubernetes.io/master
---
apiServer:
  timeoutForControlPlane: 4m0s
apiVersion: kubeadm.k8s.io/v1beta2
certificatesDir: /etc/kubernetes/pki
clusterName: kubernetes
controllerManager: {}
dns:
  type: CoreDNS
etcd:
  local:
    dataDir: /var/lib/etcd
imageRepository: k8s.gcr.io
kind: ClusterConfiguration
kubernetesVersion: v1.14.0
networking:
  dnsDomain: cluster.local
  serviceSubnet: 10.96.0.0/12
scheduler: {}

从默认的配置中能够看到，可使用imageRepository定制在集群初始化时拉取k8s所需镜像的地址。

基于默认配置定制出本次使用kubeadm初始化集群所需的配置文件

kubeadm.yaml：

apiVersion: kubeadm.k8s.io/v1beta2
kind: InitConfiguration
localAPIEndpoint:
  advertiseAddress: 18.16.202.163
  bindPort: 6443
nodeRegistration:
  taints:
  - effect: PreferNoSchedule
    key: node-role.kubernetes.io/master
---
apiVersion: kubeadm.k8s.io/v1beta2
kind: ClusterConfiguration
kubernetesVersion: v1.15.1
networking:
  podSubnet: 10.244.0.0/16

使用kubeadm默认配置初始化的集群，会在master节点打上node-role.kubernetes.io/master:NoSchedule的污点，阻止master节点接受调度运行工做负载。这里测试环境只有两个节点，因此将这个taint修改成node-role.kubernetes.io/master:PreferNoSchedule。

kubeadm初始化集群

使用kubeadm初始化集群，在master上执行下面的命令：

由于我使用的是虚拟机，只分配一个cpu，因此指定了参数--ignore-preflight-errors=NumCPU，若是你的cpu足够，不要添加这个参数.

[root@master /]# kubeadm init --config /home/kubeadm.yaml --ignore-preflight-errors=Swap --ignore-preflight-errors=NumCPU
[init] Using Kubernetes version: v1.15.1
[preflight] Running pre-flight checks
    [WARNING NumCPU]: the number of available CPUs 1 is less than the required 2
    [WARNING HTTPProxyCIDR]: connection to "10.96.0.0/12" uses proxy "https://18.16.202.169:8118". This may lead to malfunctional cluster setup. Make sure that Pod and Services IP ranges specified correctly as exceptions in proxy configuration
    [WARNING HTTPProxyCIDR]: connection to "10.244.0.0/16" uses proxy "https://18.16.202.169:8118". This may lead to malfunctional cluster setup. Make sure that Pod and Services IP ranges specified correctly as exceptions in proxy configuration
    [WARNING Service-Docker]: docker service is not enabled, please run 'systemctl enable docker.service'
[preflight] Pulling images required for setting up a Kubernetes cluster
[preflight] This might take a minute or two, depending on the speed of your internet connection
[preflight] You can also perform this action in beforehand using 'kubeadm config images pull'
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Activating the kubelet service
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [master localhost] and IPs [18.16.202.163 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "apiserver-etcd-client" certificate and key
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [master localhost] and IPs [18.16.202.163 127.0.0.1 ::1]
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 18.16.202.163]
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "sa" key and public key
[kubeconfig] Using kubeconfig folder "/etc/kubernetes"
[kubeconfig] Writing "admin.conf" kubeconfig file
[kubeconfig] Writing "kubelet.conf" kubeconfig file
[kubeconfig] Writing "controller-manager.conf" kubeconfig file
[kubeconfig] Writing "scheduler.conf" kubeconfig file
[control-plane] Using manifest folder "/etc/kubernetes/manifests"
[control-plane] Creating static Pod manifest for "kube-apiserver"
[control-plane] Creating static Pod manifest for "kube-controller-manager"
[control-plane] Creating static Pod manifest for "kube-scheduler"
[etcd] Creating static Pod manifest for local etcd in "/etc/kubernetes/manifests"
[wait-control-plane] Waiting for the kubelet to boot up the control plane as static Pods from directory "/etc/kubernetes/manifests". This can take up to 4m0s
[kubelet-check] Initial timeout of 40s passed.
[apiclient] All control plane components are healthy after 46.528199 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.15" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --upload-certs
[mark-control-plane] Marking the node master as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node master as control-plane by adding the taints [node-role.kubernetes.io/master:PreferNoSchedule]
[bootstrap-token] Using token: jrts59.18pe12atfafgcxca
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstrap-token] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstrap-token] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstrap-token] Creating the "cluster-info" ConfigMap in the "kube-public" namespace
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy

Your Kubernetes control-plane 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/

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 18.16.202.163:6443 --token jrts59.18pe12atfafgcxca \
    --discovery-token-ca-cert-hash sha256:56d6c7d7b63a9109444ece68a1b155d8a9ac049ba57febab2c72d40d8ab7d426

上面记录了完成的初始化输出的内容，根据输出的内容基本上能够看出手动初始化安装一个Kubernetes集群所须要的关键步骤。其中有如下关键内容：

[kubelet-start] 生成kubelet的配置文件”/var/lib/kubelet/config.yaml”
[certs]生成相关的各类证书
[kubeconfig]生成相关的kubeconfig文件
[control-plane]使用/etc/kubernetes/manifests目录中的yaml文件建立apiserver、controller-manager、scheduler的静态pod
[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

最后给出了将节点加入集群的命令kubeadm join 18.16.202.163:6443 --token jrts59.18pe12atfafgcxca \ --discovery-token-ca-cert-hash sha256:56d6c7d7b63a9109444ece68a1b155d8a9ac049ba57febab2c72d40d8ab7d426

若是初始化过程出现问题，使用以下命令重置：

kubeadm reset

查看一下集群状态，确认个组件都处于healthy状态：

[root@master /]# kubectl get cs
NAME                 STATUS    MESSAGE             ERROR
scheduler            Healthy   ok                  
controller-manager   Healthy   ok                  
etcd-0               Healthy   {"health":"true"}

将slaver节点添加到集群

kubeadm join 18.16.202.163:6443 --token jrts59.18pe12atfafgcxca \
    --discovery-token-ca-cert-hash sha256:56d6c7d7b63a9109444ece68a1b155d8a9ac049ba57febab2c72d40d8ab7d426

查看集群信息

在master中查看:

[root@master /]# kubectl get nodes -o wide
NAME      STATUS   ROLES    AGE     VERSION   INTERNAL-IP     EXTERNAL-IP   OS-IMAGE                KERNEL-VERSION               CONTAINER-RUNTIME
master    Ready    master   5h7m    v1.15.1   18.16.202.163   <none>        CentOS Linux 7 (Core)   4.17.6-1.el7.elrepo.x86_64   docker://18.9.8
slaver1   Ready    <none>   4h38m   v1.15.1   18.16.202.227   <none>        CentOS Linux 7 (Core)   4.17.6-1.el7.elrepo.x86_64   docker://18.9.8
slaver2   Ready    <none>   4h35m   v1.15.1   18.16.202.95    <none>        CentOS Linux 7 (Core)   4.17.6-1.el7.elrepo.x86_64   docker://18.9.8

重启kubelet：

# 重载全部修改过的配置文件
systemctl daemon-reload
# 重启kubelet
systemctl start kubelet.service
# 开机重启
systemctl enable kubelet.service

查看集群信息：

[root@master /]# kubectl cluster-info
Kubernetes master is running at https://18.16.202.163:6443
KubeDNS is running at https://18.16.202.163:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

查看Pod运行：

[root@master /]#  kubectl get pods --all-namespaces -o wide
NAMESPACE     NAME                             READY   STATUS    RESTARTS   AGE     IP              NODE      NOMINATED NODE   READINESS GATES
kube-system   coredns-5c98db65d4-gts57         1/1     Running   0          5h9m    10.244.2.2      slaver2   <none>           <none>
kube-system   coredns-5c98db65d4-qhwrw         1/1     Running   0          5h9m    10.244.1.2      slaver1   <none>           <none>
kube-system   etcd-master                      1/1     Running   2          5h9m    18.16.202.163   master    <none>           <none>
kube-system   kube-apiserver-master            1/1     Running   2          5h8m    18.16.202.163   master    <none>           <none>
kube-system   kube-controller-manager-master   1/1     Running   5          5h9m    18.16.202.163   master    <none>           <none>
kube-system   kube-flannel-ds-amd64-2lwl8      1/1     Running   0          41m     18.16.202.227   slaver1   <none>           <none>
kube-system   kube-flannel-ds-amd64-9bjck      1/1     Running   0          41m     18.16.202.95    slaver2   <none>           <none>
kube-system   kube-flannel-ds-amd64-gxxqg      1/1     Running   0          41m     18.16.202.163   master    <none>           <none>
kube-system   kube-proxy-6gxw9                 1/1     Running   0          4h39m   18.16.202.227   slaver1   <none>           <none>
kube-system   kube-proxy-rx8vv                 1/1     Running   0          4h37m   18.16.202.95    slaver2   <none>           <none>
kube-system   kube-proxy-skw5b                 1/1     Running   3          5h9m    18.16.202.163   master    <none>           <none>
kube-system   kube-scheduler-master            1/1     Running   6          5h8m    18.16.202.163   master    <none>           <none>

安装Pod Network

接下来安装flannel network add-on：

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

podsecuritypolicy.extensions/psp.flannel.unprivileged created
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

若是Node有多个网卡的话，参考flannel issues 39701，目前须要在kube-flannel.yml中使用--iface参数指定集群主机内网网卡的名称，不然可能会出现dns没法解析。须要将kube-flannel.yml下载到本地，flanneld启动参数加上--iface=<iface-name>

# 若是Node有多个网卡的话，参考flannel issues 39701，
# https://github.com/kubernetes/kubernetes/issues/39701
# 目前须要在kube-flannel.yml中使用--iface参数指定集群主机内网网卡的名称，
# 不然可能会出现dns没法解析。容器没法通讯的状况，须要将kube-flannel.yml下载到本地，
# flanneld启动参数加上--iface=<iface-name>
    containers:
      - name: kube-flannel
        image: registry.cn-shanghai.aliyuncs.com/gcr-k8s/flannel:v0.10.0-amd64
        command:
        - /opt/bin/flanneld
        args:
        - --ip-masq
        - --kube-subnet-mgr
        - --iface=ens33
        - --iface=eth0
⚠️⚠️⚠️--iface=ens33 的值，是你当前的网卡,或者能够指定多网卡

测试集群DNS是否可用

[root@master /]# kubectl run curl --image=radial/busyboxplus:curl -it
kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead.
If you don't see a command prompt, try pressing enter.

进入后执行nslookup kubernetes.default确认解析正常:

[ root@curl-6bf6db5c4f-vhsqc:/ ]$ nslookup kubernetes.default
Server:    10.96.0.10
Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local

Name:      kubernetes.default
Address 1: 10.96.0.1 kubernetes.default.svc.cluster.local

当前容器网络：

[ root@curl-6bf6db5c4f-vhsqc:/ ]$ ifconfig
eth0      Link encap:Ethernet  HWaddr D6:20:96:C7:DA:5A  
          inet addr:10.244.2.3  Bcast:0.0.0.0  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1450  Metric:1
          RX packets:22 errors:0 dropped:0 overruns:0 frame:0
          TX packets:12 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:2285 (2.2 KiB)  TX bytes:889 (889.0 B)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

[ root@curl-6bf6db5c4f-vhsqc:/ ]$ exit
Session ended, resume using 'kubectl attach curl-6bf6db5c4f-vhsqc -c curl -i -t' command when the pod is running

查看node:

# 只有网络插件也安装配置完成以后，才能会显示为ready状态

[root@master /]# kubectl get node
NAME      STATUS   ROLES    AGE     VERSION
master    Ready    master   6h45m   v1.15.1
slaver1   Ready    <none>   6h15m   v1.15.1
slaver2   Ready    <none>   6h12m   v1.15.1

从集群中移除Node

若是须要从集群中移除node2这个Node执行下面的命令：

在master节点上执行：

kubectl drain node2 --delete-local-data --force --ignore-daemonsets
kubectl delete node node2

在node2上执行：

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

kube-proxy开启ipvs

修改ConfigMap的kube-system/kube-proxy中的config.conf，mode: "ipvs"：

[root@master /]# kubectl edit cm kube-proxy -n kube-system
configmap/kube-proxy edited

cm为configmaps缩写

kube-proxy配置修改后为：

apiVersion: v1
data:
config.conf: |-
apiVersion: kubeproxy.config.k8s.io/v1alpha1
bindAddress: 0.0.0.0
clientConnection:
acceptContentTypes: ""
burst: 10
contentType: application/vnd.kubernetes.protobuf
kubeconfig: /var/lib/kube-proxy/kubeconfig.conf
qps: 5
clusterCIDR: 10.244.0.0/16
configSyncPeriod: 15m0s
conntrack:
maxPerCore: 32768
min: 131072
tcpCloseWaitTimeout: 1h0m0s
tcpEstablishedTimeout: 24h0m0s
enableProfiling: false
healthzBindAddress: 0.0.0.0:10256
hostnameOverride: ""
iptables:
masqueradeAll: false
masqueradeBit: 14
minSyncPeriod: 0s
syncPeriod: 30s
ipvs:
excludeCIDRs: null
minSyncPeriod: 0s
scheduler: ""
strictARP: false
syncPeriod: 30s
kind: KubeProxyConfiguration
metricsBindAddress: 127.0.0.1:10249
mode: "ipvs"
nodePortAddresses: null
oomScoreAdj: -999
portRange: ""
resourceContainer: /kube-proxy

加粗部分就为修改部分。

重启各个节点上的kube-proxy pod：

[root@master /]# kubectl get pod -n kube-system | grep kube-proxy | awk '{system("kubectl delete pod "$1" -n kube-system")}'
pod "kube-proxy-6gxw9" deleted
pod "kube-proxy-rx8vv" deleted
pod "kube-proxy-skw5b" deleted

查看：

[root@master /]# kubectl get pod -n kube-system -o wide | grep kube-proxy  
kube-proxy-8cwj4                 1/1     Running   0          2m35s   18.16.202.163   master    <none>           <none>
kube-proxy-j9zpz                 1/1     Running   0          2m48s   18.16.202.227   slaver1   <none>           <none>
kube-proxy-vfgjv                 1/1     Running   0          2m38s   18.16.202.95    slaver2   <none>           <none>

[root@master /]# kubectl logs kube-proxy-8cwj4  -n kube-system
I0729 07:05:35.580934       1 server_others.go:170] Using ipvs Proxier.
W0729 07:05:35.585891       1 proxier.go:401] IPVS scheduler not specified, use rr by default
I0729 07:05:35.588572       1 server.go:534] Version: v1.15.1
I0729 07:05:35.642475       1 conntrack.go:52] Setting nf_conntrack_max to 131072
I0729 07:05:35.653344       1 config.go:96] Starting endpoints config controller
I0729 07:05:35.654584       1 controller_utils.go:1029] Waiting for caches to sync for endpoints config controller
I0729 07:05:35.654629       1 config.go:187] Starting service config controller
I0729 07:05:35.654649       1 controller_utils.go:1029] Waiting for caches to sync for service config controller
I0729 07:05:35.755738       1 controller_utils.go:1036] Caches are synced for endpoints config controller
I0729 07:05:35.755806       1 controller_utils.go:1036] Caches are synced for service config controller

日志中打印出了Using ipvs Proxier，说明ipvs模式已经开启。

参考：

使用kubeadm安装Kubernetes 1.15

kubeadm安装kubernetes1.13集群

Kubernetes Install

kubectl命令大全