简介：
Kubernetes作为Google开源的容器运行平台，受到了大家的热捧。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版本以及之前，安装还是相对比较方便的，官方就有通过yum源在centos7安装kubernetes。但是在kubernetes1.6之后，安装就比较繁琐了，需要证书各种认证，对于刚接触kubernetes的人来说很不友好。
docker : kubernetes依赖的容器运行时
kubelet: kubernetes最核心的agent组件,每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,只可以在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：
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%,}"
所有节点前置配置:
1.1 关闭防火墙
systemctl stop firewalld
systemctl disable firewalldiptables对bridge的数据进行处理:
创建/etc/sysctl.d/k8s.conf文件，添加如下内容：
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。
modprobe br_netfilter
sysctl -p /etc/sysctl.d/k8s.conf1.2 禁用SELinux
setenforce 0编辑文件/etc/selinux/config，将SELINUX修改为disabled，如下：
sed -i 's/SELINUX=permissive/SELINUX=disabled/' /etc/sysconfig/selinux
#SELINUX=disabled1.3 关闭系统Swap
Kubernetes 1.8开始要求关闭系统的Swap，如果不关闭，默认配置下kubelet将无法启动。方法一,通过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。
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 1.4 kube-proxy开启ipvs的前置条件
由于ipvs已经加入到了内核的主干，所以为kube-proxy开启ipvs的前提需要加载以下的内核模块：
ip_vs
ip_vs_rr
ip_vs_wrr
ip_vs_sh
nf_conntrack_ipv4
在所有的Kubernetes节点node1和node2上执行以下脚本:
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上面脚本创建了的/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。
接下来还需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如果以上前提条件如果不满足，则即使kube-proxy的配置开启了ipvs模式，也会退回到iptables模式。
1.5 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.1.6 修改docker cgroup driver为systemd
对于使用systemd作为init system的Linux的发行版，使用systemd作为docker的cgroup driver可以确保服务器节点在资源紧张的情况更加稳定，因此这里修改各个节点上docker的cgroup driver为systemd。
创建或修改/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: systemd1.7 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 kubectl1.8 安装kubeadm init初始化集群所需docker镜像
开始初始化集群之前可以使用kubeadm config images pull预先在各个节点上拉取所k8s需要的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
在网上找了其他的资源，创建一个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"上面的所有操作可以在一个节点上面完成，然后对进行复制即可。
集群操作
1.1 kubeadm初始化配置
使用kubeadm config print init-defaults可以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: {}从默认的配置中可以看到，可以使用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作负载。这里测试环境只有两个节点，所以将这个taint修改为node-role.kubernetes.io/master:PreferNoSchedule。
1.2 kubeadm初始化集群
使用kubeadm初始化集群，在master上执行下面的命令：
因为我使用的是虚拟机，只分配一个cpu，所以指定了参数--ignore-preflight-errors=NumCPU，如果你的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
如果初始化过程出现问题，使用如下命令重置：
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 1.3 查看集群信息
在master中查看:
[root@master /]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
master NotReady master 32m v1.15.1
slaver1 NotReady <none> 3m4s v1.15.1
slaver2 NotReady <none> 42s v1.15.1重启kubelet：
# 重载所有修改过的配置文件
systemctl daemon-reload
# 重启kubelet
systemctl start 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
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system coredns-5c98db65d4-gts57 0/1 Pending 0 4h4m
kube-system coredns-5c98db65d4-qhwrw 0/1 Pending 0 4h4m
kube-system etcd-master 1/1 Running 2 4h3m
kube-system kube-apiserver-master 1/1 Running 2 4h3m
kube-system kube-controller-manager-master 1/1 Running 5 4h3m
kube-system kube-proxy-6gxw9 1/1 Running 0 3h34m
kube-system kube-proxy-rx8vv 1/1 Running 0 3h31m
kube-system kube-proxy-skw5b 1/1 Running 3 4h4m
kube-system kube-scheduler-master 1/1 Running 6 4h3m