使用kubeadm 安裝 kubernetes 1.15.1

時間 2019-11-11

標籤使用 kubeadm 安裝 kubernetes 1.15.1 简体版

原文原文鏈接

簡介：

Kubernetes做爲Google開源的容器運行平臺，受到了你們的熱捧。搭建一套完整的kubernetes平臺，也成爲試用這套平臺必須邁過的坎兒。kubernetes1.5版本以及以前，安裝仍是相對比較方便的，官方就有經過yum源在centos7安裝kubernetes。可是在kubernetes1.6以後，安裝就比較繁瑣了，須要證書各類認證，對於剛接觸kubernetes的人來講很不友好。html

docker : kubernetes依賴的容器運行時
kubelet: kubernetes最核心的agent組件,每一個節點都會啓動一個,負責像pods及節點的生命週期等管理
kubectl: kubernetes的命令行控制工具,只能夠在master上使用.
kubeadm: 用來bootstrap kubernetes. 初始化一個k8s集羣.

架構說明：

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

配置代理上網：

etc/profile文件內添加：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%,}"

注意這裏不能使用星號模糊匹配，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，能夠直接命令設置：git

unset https_proxy
unset http_proxy

再次使用代理：github

source /etc/profile

全部節點前置配置:

關閉防火牆

systemctl stop firewalld
systemctl disable firewalld

iptables對bridge的數據進行處理:docker

建立/etc/sysctl.d/k8s.conf文件，添加以下內容：shell

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

執行命令使修改生效。json

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

禁用SELinux

setenforce 0

編輯文件/etc/selinux/config，將SELINUX修改成disabled，以下：bootstrap

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

#SELINUX=disabled

關閉系統Swap

Kubernetes 1.8開始要求關閉系統的Swap，若是不關閉，默認配置下kubelet將沒法啓動。方法一,經過kubelet的啓動參數–fail-swap-on=false更改這個限制。方法二,關閉系統的Swap。centos

swapoff -a

修改/etc/fstab文件，註釋掉SWAP的自動掛載，使用free -m確認swap已經關閉。

#註釋掉swap分區
[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開啓ipvs的前置條件

因爲ipvs已經加入到了內核的主幹，因此爲kube-proxy開啓ipvs的前提須要加載如下的內核模塊：

ip_vs
ip_vs_rr
ip_vs_wrr
ip_vs_sh
nf_conntrack_ipv4

在全部的Kubernetes節點node1和node2上執行如下腳本:

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

上面腳本建立了的/etc/sysconfig/modules/ipvs.modules文件，保證在節點重啓後能自動加載所需模塊。使用lsmod | grep -e ip_vs -e nf_conntrack_ipv4命令查看是否已經正確加載所需的內核模塊。

接下來還須要確保各個節點上已經安裝了ipset軟件包。

yum install -y ipset

爲了便於查看ipvs的代理規則，最好安裝一下管理工具ipvsadm 。

yum install -y ipvsadm

若是以上前提條件若是不知足，則即便kube-proxy的配置開啓了ipvs模式，也會退回到iptables模式。

安裝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
已加載插件：fastestmirror
可安裝的軟件包
 * 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

安裝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

我這裏安裝的是docker-ce 18.09

設置爲開機啓動：

[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爲systemd

對於使用systemd做爲init system的Linux的發行版，使用systemd做爲docker的cgroup driver能夠確保服務器節點在資源緊張的狀況更加穩定，所以這裏修改各個節點上docker的cgroup driver爲systemd。

建立或修改/etc/docker/daemon.json：

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

重啓docker：

systemctl restart docker

docker info | grep Cgroup
Cgroup Driver: systemd

安裝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

測試地址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

安裝:

yum makecache fast
yum install -y kubelet kubeadm kubectl

安裝kubeadm init初始化集羣所需docker鏡像

開始初始化集羣以前可使用kubeadm config images pull預先在各個節點上拉取所k8s須要的docker鏡像

[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

明顯是網絡問題，k8s.gcr.io 資源獲取不了

在網上找了其餘的資源，建立一個shell文件，粘貼運行

MY_REGISTRY=gcr.azk8s.cn/google-containers

## 拉取鏡像
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
 
#刪除無用的鏡像
docker images | grep ${MY_REGISTRY} | awk '{print "docker rmi "  $1":"$2}' | sh -x

echo "end"

上面的全部操做能夠在一個節點上面完成，而後對進行復制便可。

集羣操做

kubeadm初始化配置

使用kubeadm config print init-defaults能夠打印集羣初始化默認的使用的配置：

[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: {}

從默認的配置中能夠看到，可使用imageRepository定製在集羣初始化時拉取k8s所需鏡像的地址。

基於默認配置定製出本次使用kubeadm初始化集羣所需的配置文件

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默認配置初始化的集羣，會在master節點打上node-role.kubernetes.io/master:NoSchedule的污點，阻止master節點接受調度運行工做負載。這裏測試環境只有兩個節點，因此將這個taint修改成node-role.kubernetes.io/master:PreferNoSchedule。

kubeadm初始化集羣

使用kubeadm初始化集羣，在master上執行下面的命令：

由於我使用的是虛擬機，只分配一個cpu，因此指定了參數--ignore-preflight-errors=NumCPU，若是你的cpu足夠，不要添加這個參數.

[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

上面記錄了完成的初始化輸出的內容，根據輸出的內容基本上能夠看出手動初始化安裝一個Kubernetes集羣所須要的關鍵步驟。其中有如下關鍵內容：

[kubelet-start] 生成kubelet的配置文件」/var/lib/kubelet/config.yaml」
[certs]生成相關的各類證書
[kubeconfig]生成相關的kubeconfig文件
[control-plane]使用/etc/kubernetes/manifests目錄中的yaml文件建立apiserver、controller-manager、scheduler的靜態pod
[bootstraptoken]生成token記錄下來，後邊使用kubeadm join往集羣中添加節點時會用到

下面的命令是配置常規用戶如何使用kubectl訪問集羣：

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

最後給出了將節點加入集羣的命令kubeadm join 18.16.202.163:6443 --token jrts59.18pe12atfafgcxca \ --discovery-token-ca-cert-hash sha256:56d6c7d7b63a9109444ece68a1b155d8a9ac049ba57febab2c72d40d8ab7d426

若是初始化過程出現問題，使用以下命令重置：

kubeadm reset

查看一下集羣狀態，確認個組件都處於healthy狀態：

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

將slaver節點添加到集羣

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

查看集羣信息

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

重啓kubelet：

# 重載全部修改過的配置文件
systemctl daemon-reload
# 重啓kubelet
systemctl start kubelet.service
# 開機重啓
systemctl enable kubelet.service

查看集羣信息：

[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運行：

[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>

安裝Pod Network

接下來安裝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有多個網卡的話，參考flannel issues 39701，目前須要在kube-flannel.yml中使用--iface參數指定集羣主機內網網卡的名稱，不然可能會出現dns沒法解析。須要將kube-flannel.yml下載到本地，flanneld啓動參數加上--iface=<iface-name>

# 若是Node有多個網卡的話，參考flannel issues 39701，
# https://github.com/kubernetes/kubernetes/issues/39701
# 目前須要在kube-flannel.yml中使用--iface參數指定集羣主機內網網卡的名稱，
# 不然可能會出現dns沒法解析。容器沒法通訊的狀況，須要將kube-flannel.yml下載到本地，
# flanneld啓動參數加上--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，是你當前的網卡,或者能夠指定多網卡

測試集羣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.

進入後執行nslookup kubernetes.default確認解析正常:

[ 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

當前容器網絡：

[ 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:

# 只有網絡插件也安裝配置完成以後，才能會顯示爲ready狀態

[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

從集羣中移除Node

若是須要從集羣中移除node2這個Node執行下面的命令：

在master節點上執行：

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

在node2上執行：

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開啓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爲configmaps縮寫

kube-proxy配置修改後爲：

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

加粗部分就爲修改部分。

重啓各個節點上的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

日誌中打印出了Using ipvs Proxier，說明ipvs模式已經開啓。