Kubernetes 1.16.9 kubeadm 集群安装

虚拟机环境

IP	版本	角色
10.211.55.41	CentOS 7.8.2003	k8s-master-1
10.211.55.42	CentOS 7.8.2003	k8s-node-1
10.211.55.43	CentOS 7.8.2003	k8s-node-2

处理不必要的麻烦

• 代理

  宿主机有开 *X，虚拟机上的网络都是走宿主机的代理，不然 k8s 安装不成。下面有提供离线安装包。下面开启代理：

# 系统代理
$ cat >> /etc/profile << EOF

export http_proxy=http://192.168.1.188:1087
export https_proxy=http://192.168.1.188:1087
EOF

$ source /etc/profile

# Docker 拉取镜像代理配置
$ mkdir -p mkdir -p /lib/systemd/system/docker.service.d
$ cat >> /lib/systemd/system/docker.service.d/socks5-proxy.conf << EOF
[Service]
Environment="ALL_PROXY=socks5://192.168.1.188:1086"
EOF

• 字符集

  可以查看这篇博客

• 升级内核

  可以查看这篇博客

• 安装常用工具

$  yum -y install wget vim

• 本篇博客所有依赖如下：

  安装包

• 其他操作

### 三台机器同样操作
# 每天机器的 UUID 要不同
$ cat /sys/class/dmi/id/product_uuid

# 修改 hosts
$ cat >> /etc/hosts << EOF

10.211.55.41 k8s-master-1
10.211.55.42 k8s-node-1
10.211.55.43 k8s-node-2
EOF

# 关闭防火墙和 SELinux
$ systemctl disable firewalld && systemctl stop firewalld && setenforce 0
$ sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

# 关闭 Swap，自 1.8 开始，k8s 要求关闭系统 Swap，如果不关闭，kubelet 无法启动。
# swappiness 的值的大小对如何使用 swap 分区是有着很大的联系的。swappiness = 0 的时候表示最大限度使用物理内存，然后才是 swap 空间，swappiness ＝ 100 的时候表示积极的使用 swap 分区，并且把内存上的数据及时的搬运到 swap 空间里面。linux 的基本默认设置为 60。
$ swapoff -a
$ sed -i.bak '/swap/s/^/#/' /etc/fstab
# /dev/mapper/centos-swap swap                    swap    defaults        0 0

# 开机去加载系统配置 Modeles
$ cat > /etc/rc.sysinit << EOF
#!/bin/bash
for file in /etc/sysconfig/modules/*.modules ; do [ -x $file ] && $file; done
EOF

# flannel 网络需要 br_netfilter 模块支持
$ cat > /etc/sysconfig/modules/br_netfilter.modules << EOF
modprobe br_netfilter
EOF

$ chmod 755 /etc/sysconfig/modules/br_netfilter.modules \
  && bash /etc/sysconfig/modules/br_netfilter.modules

# 最大限度使用屋里空间、开启桥接网络和转发
$ cat <<EOF >  /etc/sysctl.d/k8s.conf
vm.swappiness                       = 0
net.bridge.bridge-nf-call-ip6tables = 1
net.ipv4.ip_forward                 = 1
net.bridge.bridge-nf-call-iptables  = 1
EOF

sysctl --system

如果不关闭 Swap 也可，需要修改 kubelet 的启动配置项 --fail-swap-on=false 。配置文件：/etc/sysconfig/kubelet。KUBELET_EXTRA_ARGS=–fail-swap-on=false

• kube-proxy 开启 ipvs 的前置条件

  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：

模块	说明
ip_vs
ip_vs_rr
ip_vs_wrr
ip_vs_sh
nf_conntrack_ipv4	# 从内核 4.19.1 开始已经修改成：nf_conntrack

$ 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
EOF
$ chmod 755 /etc/sysconfig/modules/ipvs.modules && bash /etc/sysconfig/modules/ipvs.modules && lsmod | grep -e ip_vs -e nf_conntrack_ipv4

  还需要确保各个节点上已经安装了 ipset 软件包 yum -y install 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 -y install 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。

安装 Docker

• 删除旧版本

$ sudo yum remove docker \
                  docker-client \
                  docker-client-latest \
                  docker-common \
                  docker-latest \
                  docker-latest-logrotate \
                  docker-logrotate \
                  docker-engine

• 安装稳定 yum 源仓库

$ 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

• 安装

# 查看版本
$ yum list docker-ce --showduplicates | sort -r
$ yum install -y docker-ce-18.09.9 docker-ce-cli-18.09.9 containerd.io

• 启动

$ systemctl enable docker && systemctl start docker

修改 docker cgoup driver 为 systemd

  CRI installation 中指出，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。

• 配置

#

$ mkdir /etc/docker
$ cat > /etc/docker/daemon.json <<EOF
{
  # "registry-mirrors": ["https://tpzm7vxj.mirror.aliyuncs.com"], # 国内镜像加速
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "100m"
  },
  "storage-driver": "overlay2",
  "storage-opts": [
    "overlay2.override_kernel_check=true"
  ]
}
EOF

$ systemctl daemon-reload && systemctl restart docker

使用 kubeadm 部署 Kubernetes

安装 kubeadm 和 kubelet

• 引用官方 yum 源：

$ 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


$ yum install -y kubelet-1.16.9 kubeadm-1.16.9 kubectl-1.16.9

  安装完毕，如图：

$ systemctl enable kubelet.service && systemctl start kubelet

kubelet 现在每隔几秒就会重启，因为它陷入了一个等待 kubeadm 指令的死循环。

  使用 kubelet --help 查看很多参数丢已经 DEPRECATED 了，官方推荐 kubelet 使用 --config 指定配置文件，并在配置文件中指定原来这些参数所配置的内容，参考。

使用 kubeadm 初始化集群

$ kubeadm init --kubernetes-version=v1.16.9 --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address=10.211.55.41

1. –kubernetes-version：指定 k8s 版本
2. –pod-network-cidr：fiannel 作为 pod 网络查件，指定范围
3. –apiserver-advertise-address：api-server 所在主机地址

这里初始化会从 Google 的镜像源拉取 Docker 镜像，如果没有????????的话应该会报错，也可离线 docker load -i 包 导出，文章头部已经提供了下载。

  重新进行初始化操作：

安装之前记得把代理取消掉。

$ kubeadm init --kubernetes-version=v1.16.9 --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address=10.211.55.41
[init] Using Kubernetes version: v1.16.9
[preflight] Running pre-flight checks
[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 "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [k8s-master-1 kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.211.55.41]
[certs] Generating "apiserver-kubelet-client" certificate and key
[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 [k8s-master-1 localhost] and IPs [10.211.55.41 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [k8s-master-1 localhost] and IPs [10.211.55.41 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "apiserver-etcd-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
[apiclient] All control plane components are healthy after 20.502757 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.16" 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 k8s-master-1 as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node k8s-master-1 as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: avmkea.3i15b2xvcdnrrwvj
[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 10.211.55.41:6443 --token avmkea.3i15b2xvcdnrrwvj \
    --discovery-token-ca-cert-hash sha256:c7811dd5d821821d0fbdb90943a80a7176b8844ca6c24774833b369c258f8ee2

  观看上方日志，可以发现有这样一些操作：

• [kubelet-start] 生成 kubelet 的配置文件 /var/lib/kubelet/config.yaml
• [certificates] 生成相关的各种证书
• [kubeconfig] 生成相关的 kubeconfig 文件
• [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
• 配置用户通过 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

• 新节点加入（其他工作节点使用此命令加入即可）

$ kubeadm join 10.211.55.41:6443 --token avmkea.3i15b2xvcdnrrwvj \
    --discovery-token-ca-cert-hash sha256:c7811dd5d821821d0fbdb90943a80a7176b8844ca6c24774833b369c258f8ee2

  查看一下集群状态，确认组件都处于 healthy 状态：

$ kubectl get cs
NAME                 AGE
scheduler            <unknown>
controller-manager   <unknown>
etcd-0               <unknown>
$ kubectl get cs -o=go-template='{{printf "|NAME|STATUS|MESSAGE|\n"}}{{range .items}}{{$name := .metadata.name}}{{range .conditions}}{{printf "|%s|%s|%s|\n" $name .status .message}}{{end}}{{end}}'
|NAME|STATUS|MESSAGE|
|scheduler|True|ok|
|controller-manager|True|ok|
|etcd-0|True|{"health":"true"}|

  这里是 unknown 请参考文章：https://segmentfault.com/a/1190000020912684。

集群初始化如果遇到问题可以使用 kubeadm reset 进行清理。

安装 Pod Network

  查看节点的状态：

$ kubectl get nodes
NAME           STATUS     ROLES    AGE     VERSION
k8s-master-1   NotReady   master   3m50s   v1.16.9

  STATUS 的值都是 NotReady，这是因为网络插件的问题，k8s 网络查件选型有很多种，这里使用网络插件 flannel。

$ kubectl apply -f kube-flannel.yml
podsecuritypolicy.policy/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.apps/kube-flannel-ds-amd64 created
daemonset.apps/kube-flannel-ds-arm64 created
daemonset.apps/kube-flannel-ds-arm created
daemonset.apps/kube-flannel-ds-ppc64le created
daemonset.apps/kube-flannel-ds-s390x created

✨ 如果 Node 有多个网卡的话，参考 issues，目前需要在 kube-flannel.yml 中使用 --iface 参数指定集群主机内网网卡的名称，否则可能会出现 dns 无法解析。需要将 kube-flannel.yml 下载到本地，flanneld 启动参数加上 --iface=<iface-name>

......
containers:
      - name: kube-flannel
        image: quay.io/coreos/flannel:v0.11.0-amd64
        command:
        - /opt/bin/flanneld
        args:
        - --ip-masq
        - --kube-subnet-mgr
        - --iface=eth1
......

  再次查看节点和 Pod 状态，确保都在 Ready/Running 状态：

$ kubectl get nodes -o wide
NAME           STATUS   ROLES    AGE     VERSION   INTERNAL-IP    EXTERNAL-IP   OS-IMAGE                KERNEL-VERSION                CONTAINER-RUNTIME
k8s-master-1   Ready    master   5m17s   v1.16.9   10.211.55.41   <none>        CentOS Linux 7 (Core)   4.4.236-1.el7.elrepo.x86_64   docker://18.9.9

$ kubectl get pods -o wide -n kube-system
NAME                                   READY   STATUS    RESTARTS   AGE     IP             NODE           NOMINATED NODE   READINESS GATES
coredns-5644d7b6d9-m2tn4               1/1     Running   0          5m10s   10.244.0.2     k8s-master-1   <none>           <none>
coredns-5644d7b6d9-n4kls               1/1     Running   0          5m10s   10.244.0.3     k8s-master-1   <none>           <none>
etcd-k8s-master-1                      1/1     Running   0          4m25s   10.211.55.41   k8s-master-1   <none>           <none>
kube-apiserver-k8s-master-1            1/1     Running   0          4m6s    10.211.55.41   k8s-master-1   <none>           <none>
kube-controller-manager-k8s-master-1   1/1     Running   0          4m31s   10.211.55.41   k8s-master-1   <none>           <none>
kube-flannel-ds-amd64-cl2gm            1/1     Running   0          53s     10.211.55.41   k8s-master-1   <none>           <none>
kube-proxy-6k77w                       1/1     Running   0          5m9s    10.211.55.41   k8s-master-1   <none>           <none>
kube-scheduler-k8s-master-1            1/1     Running   0          4m7s    10.211.55.41   k8s-master-1   <none>           <none>

让 Master 节点参与负载

  使用 kubeadm 初始化的集群，出于安全考虑 Pod 不会被调度到 Master Node 上，也就是说 Master Node 不参与工作负载。这是因为当前的 master 节点打上了 node-role.kubernetes.io/master:NoSchedule 的污点：

$ kubectl describe node k8s-master-1 | grep Taint
Taints:             node-role.kubernetes.io/master:NoSchedule

  如果你想让 Master 节点参与负载，那么去掉这个污点即可：

$ kubectl taint nodes k8s-master-1 node-role.kubernetes.io/master-
node/k8s-master-1 untainted

测试 DNS

$ 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.

$ 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

从集群中移除节点

  在 Master 上执行：

$ kubectl drain k8s-node-1 --delete-local-data --force --ignore-daemonsets
$ kubectl delete node k8s-node-1

  在 k8s-node-1 上执行：

$ kubeadm reset

Over！！！最后安装完了记得取消掉代理。