K8S之路(一) -- Kubeadm搭建K8S集羣

一：摘要概述

Kubernetes簡稱K8S，8指代中間八個字母，希臘語舵手。大衆理解的K8S都是對容器進行管理，Docker另外含義集裝箱，命名K8S的初衷就是希望可以對這些集裝箱進行管理。有偉大願景的組織才能做出偉大的貢獻，K8S的劃時代後續正文中慢慢體會，本文將幫助小白新手搭建K8S集羣。別被集羣嚇到，直白點就是K8S運行環境，只不過多加點節點機器

二：軟硬件準備

硬件的相關要求官網上有明確指導，最低要求2核16G。其中Node即工作節點推薦4核，爲了一帆風順本文將使用超高標準操作。但是如果真是小白更建議用虛擬機操作，乾淨的配置環境對於搭建K8S集羣來講會少很多困擾

序列號	操作系統	CPU	內存	IP地址
1	CentOS7	8	128	192.168.15.12
2	CentOS7	8	128	192.168.15.13
3	CentOS7	8	128	192.168.15.14

軟件準備無非就是安裝包，但是這裏只會闡述相關軟件版本，下載前請先執行後續步驟再下載。

序列號	組件名稱	版本	說明
1	kubeadm	1.16.0	初始化Master節點，僅僅需要Master節點安裝
2	kubelet	1.16.0	Node節點運行管理，Master與Node都需要安裝
3	kubectl	1.16.0	K8S命令工具，Master與Node都可以裝上

安裝K8S之前每臺服務器保證安裝Docker Engine，推薦版本18.09。安裝完成後修改daemon.json文件，詳細的Docker安裝請移步Docker安裝。修改內容如下，因爲Docker默認採用systemd驅動，但是K8S採用cgroupfs驅動，需要將兩者統一。統一的方式可以修改Docker，也可以修改K8S。K8S咱還沒裝好，就統一修改Docker

// 執行命令
vim /etc/docker/daemon.json

// 修改內容
 "exec-opts": [
        "native.cgroupdriver=cgroupfs"
    ]

三：環境準備

K8S搭建需要做許多相關配置，請務必按要求操作。不要存在僥倖心理，作者的經歷就是血淋淋的教訓

3.1 關閉防火牆

爲這事兒個人絞盡腦汁想保留防火牆，按照公司規定這是必須的防護。但是，隨着K8S安裝後的應用擴展你會發現天真寫你腦門上，還是關了吧。端口太多且有些應用組件通信端口不好找

// CentOS7檢查firewall防火牆
systemctl status firewalld.service

// 關閉防火牆
systemctl stop firewalld.service

// 解除開機自啓動
systemctl disable firewalld.service

3.2 主機名解析

保證每臺機器可以根據主機名字解析出相應的IP地址，首先修改/etc/hostname文件爲機器命名，然後修改/etc/hosts文件綁定主機名與IP

序列號	IP地址	主機名
1	192.168.15.12	k8s-master
2	192.168.15.13	k8s-node1
3	192.168.15.14	k8s-node2

// 方式1：文件修改
vim /etc/hostname

// 方式2：命令修改,CentOS7提供hostnamectl系列命令。下述命令執行完後查看/etc/hostname文件你就明白了
hostnamectl set-hostname k8s-master

// 最後結果查詢,主機名有靜態名、瞬態名等，自行了解
方式一：hostname
方拾二：hostnamectl status

3.3 關閉Swap

執行命令free -h可以查看主機內存使用情況，控制檯輸出形式如下：Mem是真正的物理內存，當這個內存達到設定使用最高比例後開始使用Swap內存，Swap內存是磁盤虛擬內存，詳解請自行學習。這裏操作就是必須關閉釋放禁止使用Swap

// 臨時關閉,開機失效
swapoff -a

// 永久關閉，但都是重啓生效。機器不能重啓請先使用臨時命令操作
方式一：sed -i 's/.*swap.*/#&/' /etc/fstab
方式二：修改文件/etc/fstab，將Swap那行註釋

3.4 關閉Selinux

Selinux增強型Linux，2.6集成爲Linux模塊，Linux的安全子系統。打開可能對後續目錄掛載產生影響，部署時將其關閉

// 臨時關閉
setenforce 0

// 永久關閉
方式一：sed -i 's/SELINUX=permissive/SELINUX=disabled/' /etc/sysconfig/selinux
	   sed -i "s/SELINUX=enforcing/SELINUX=disabled/g" /etc/selinux/config

方式二：vim /etc/selinux/config 和文件 vim /etc/sysconfig/selinux 將SELINUX參數設置爲disabled

3.5 關閉Dnsmasp

Dnsmasp一個網絡工具，可能導致Docker容器無法解析域名

// 關閉服務
systemctl stop dnsmasp

// 禁止開機自啓動
systemctl disable dnsmasp

3.6 設置系統參數

// 執行命令
vim /etc/sysctl.d/k8s.conf 

// 文件內容
net.bridge.bridge-nf-call-iptables=1
net.bridge.bridge-nf-call-ip6tables=1
net.ipv4.ip_forward=1
vm.swappiness=1
vm.overcommit_memory=1
vm.panic_on_oom=0
fs.inotify.max_user_watches=89100

// 查看效果
sysctl --system

3.7 設置系統時鐘

// 調整系統時區
timedatectl set-timezone Asia/Shanghai

// UTC時鐘與硬件一致
timedatectl set-local-rtc 0

3.8 配置阿里雲K8S yum源

K8S默認的下載源是google，國外的肯定牆了過不去。所以yum下載前需要配置國內的yum源

// 執行命令 
vim /etc/yum.repos.d/kubernetes.repo

// 文件內容
[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

四：下載安裝

請仔細檢查是否按照要求在所有主機上執行了三步驟，確保！確保！確保！很重要的事情提示三遍。上述三步驟一定要在所有主機上執行

4.1 Master主機操作

yum 下載安裝相關組件

// 安裝kubeadm、kubectl、kubelet
yum install -y kubeadm-1.16.0-0 kubectl-1.16.0-0 kubelet-1.16.0-0

啓動kublet應用

systemctl enable kubelet && systemctl start kubelet

初始化Master

kubeadm init --image-repository registry.aliyuncs.com/google_containers --kubernetes-version v1.16.0 --apiserver-advertise-address 自己的Mater主機IP地址 --pod-network-cidr=10.244.0.0/16 --token-ttl 0

後續操作，爲了可以使用kubectl客戶端命令

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

安裝通信網絡組件flanneld，因爲官方的yml下載源在國外，國內請查看第六節的yml文件。這個應用組件用於通信，此時未安裝使用命令kubectl get nodes 查看節點狀態發現其爲NotReady，裝完後將會變成Ready纔是正確的狀態

// 任意位置創建文件
touch kube-flanneld.yml

// 將第五節內容複製粘貼到文件中，並執行下述命令
kubectl apply -f kube-flanneld.yml

4.2 Node操作

yum 下載安裝相關組件

// 安裝kubeadm、kubectl、kubelet
yum install -y kubectl-1.16.0-0 kubelet-1.16.0-0

加入集羣，此時加入集羣的命令可以去Master節點上獲取。其實初始化完畢後的Master也會進行輸出，如果沒有記錄就去查詢即可

// Master節點執行命令，查詢加入集羣命令
kubeadm token create --print-join-command

// Node節點執行Master節點控制檯輸出內容即可

如果想在Node節點上操作kubectl命令請將Master節點的$HOME/.kube目錄下的config文件拷貝到Node節點的相同位置即可，不然會提示8080什麼的相關信息

五：踩坑小結

5.1 Node節點NotReady

做完所有操作後發現Node節點狀態任然是NotReady，此時執行命令kubectl get pods -n kube-system發現有的狀態顯示不是Running，此時去Node節點查看並沒有對應的Docker鏡像，處理方式就是將Master節點下載好的相關鏡像save然後Node節點load完畢後即可恢復Ready狀態。因爲本人已經安裝好，所以下圖所有都是Running

5.2 網絡錯誤

錯誤輸出

ROR FileContent--proc-sys-net-bridge-bridge-nf-call-iptables]: /proc/sys/net/bridge/bridge-nf-call-iptables contents are not set to 1

修改方法

echo 1 > /proc/sys/net/bridge/bridge-nf-call-iptables
echo 1 > /proc/sys/net/bridge/bridge-nf-call-ip6tables

六：kube-flanneld.yml文件

---
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:v0.11.0-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:v0.11.0-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:v0.11.0-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:v0.11.0-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:v0.11.0-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:v0.11.0-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:v0.11.0-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:v0.11.0-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:v0.11.0-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:v0.11.0-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