K8S集群搭建流程

1. 环境准备

三台Centos7主机(3G及以上RAM,2核CPU,40G硬盘空间)
网络环境:要求主机之间能够互相通信

k8s-node1 10.15.0.21
k8s-node2 10.15.0.22
k8s-node3 10.15.0.23

2. 配置过程

本环节如果没有特殊说明，其所有命令在所有主机上都要执行

1. 配置主机名

# 第一台主机
hostnamectl set-hostname k8s-node1
# 第二台主机
hostnamectl set-hostname k8s-node2
# 第三台主机
hostnamectl set-hostname k8s-node3

2. 关闭防火墙

# 关闭防火墙
systemctl stop firewalld
# 关闭防火墙的开机自启
systemctl disable firewalld

3. 关闭 swap 分区

# 增加集群稳定性,防止服务器在内存不足的时候使用 swap 分区降低集群性能

# 先临时禁用 swap 分区
sudo swapoff -a
# 修改/etc/fstab文件，注释掉Swap分区的相关行
sed -ri 's/.*swap.*/#&/' /etc/fstab

4. 同步服务器时间

# 安装时间同步工具
yum install ntpdate -y
# 使用微软的时间同步服务器
ntpdate time.windows.com

5. 安装 containerd

# 安装 yum-config-manager 相关依赖
yum install -y yum-utils device-mapper-persistent-data lvm2
# 添加软件源信息
yum-config-manager --add-repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
sed -i 's+download.docker.com+mirrors.aliyun.com/docker-ce+' /etc/yum.repos.d/docker-ce.repo
yum makecache fast
# 安装 containerd
yum install -y containerd.io cri-tools
# 配置 containerd
cat > /etc/containerd/config.toml <<EOF
disabled_plugins = ["restart"]
[plugins.linux]
shim_debug = true
[plugins.cri.registry.mirrors."docker.io"]
endpoint = ["https://3j4odb52.mirror.aliyuncs.com"]
[plugins.cri]
sandbox_image = "registry.aliyuncs.com/google_containers/pause:3.9"
EOF
# 启动 containerd 服务
systemctl start containerd
# 设置成开机自启
systemctl enable containerd
# 配置 containerd 网络
cat > /etc/modules-load.d/containerd.conf <<EOF
overlay
br_netfilter
EOF
# 配置 k8s 网络
cat > /etc/sysctl.d/k8s.conf <<EOF
net.bridge.bridge-nf-call-iptables = 1
net.bridge.bridge-nf-call-ip6tables = 1
net.ipv4.ip_forward = 1
EOF
# 加载模块
modprobe overlay
modprobe br_netfilter
# 查看 k8s 配置
sysctl -p /etc/sysctl.d/k8s.conf

6. 配置 k8s 镜像源

cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF

# 查看镜像仓库
yum repolist

7. 安装 k8s

yum install -y kubelet kubeadm kubectl

8. 启动 kubeket

systemctl start kubelet
systemctl enable kubelet

3. 初始化 k8s 集群

在control-plane主机上执行:

kubeadm init \
--apiserver-advertise-address=10.15.0.21 \
--pod-network-cidr=10.244.0.0/16 \
--image-repository registry.aliyuncs.com/google_containers

执行完成后的回显如下，会给一段其他节点加入该集群的命令:

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

Alternatively, if you are the root user, you can run:

  export KUBECONFIG=/etc/kubernetes/admin.conf

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 10.15.0.21:6443 --token ee016g.60vwpgmf6z7sgdyy \
        --discovery-token-ca-cert-hash sha256:f5bf614871aa605779a1bf14ef87aa6a866f13c61219702948640fac6d82e96e

首先根据回显在control-plane主机执行以下三条命令:

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

然后在其他的worknode主机上执行加入集群的命令:

kubeadm join 10.15.0.21:6443 --token ee016g.60vwpgmf6z7sgdyy \
        --discovery-token-ca-cert-hash sha256:f5bf614871aa605779a1bf14ef87aa6a866f13c61219702948640fac6d82e96e

在control-plane主机上执行命令查看节点是否加入：

watch -n 1 -d kubectl get nodes

发现节点都已经加入进来了，但是都没有准备就绪，这时候安装Flannel网络插件实现跨主机Pod通信，让节点能够正常就绪:

vi kube-flannel.yml

将以下内容复制到文件中(也可以自己去gihub上下载以后复制，需梯子):

https://github.com/flannel-io/flannel

apiVersion: v1
kind: Namespace
metadata:
  labels:
    k8s-app: flannel
    pod-security.kubernetes.io/enforce: privileged
  name: kube-flannel
---
apiVersion: v1
kind: ServiceAccount
metadata:
  labels:
    k8s-app: flannel
  name: flannel
  namespace: kube-flannel
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  labels:
    k8s-app: flannel
  name: flannel
rules:
- apiGroups:
  - ""
  resources:
  - pods
  verbs:
  - get
- apiGroups:
  - ""
  resources:
  - nodes
  verbs:
  - get
  - list
  - watch
- apiGroups:
  - ""
  resources:
  - nodes/status
  verbs:
  - patch
- apiGroups:
  - networking.k8s.io
  resources:
  - clustercidrs
  verbs:
  - list
  - watch
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  labels:
    k8s-app: flannel
  name: flannel
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: flannel
subjects:
- kind: ServiceAccount
  name: flannel
  namespace: kube-flannel
---
apiVersion: v1
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"
      }
    }
kind: ConfigMap
metadata:
  labels:
    app: flannel
    k8s-app: flannel
    tier: node
  name: kube-flannel-cfg
  namespace: kube-flannel
---
apiVersion: apps/v1
kind: DaemonSet
metadata:
  labels:
    app: flannel
    k8s-app: flannel
    tier: node
  name: kube-flannel-ds
  namespace: kube-flannel
spec:
  selector:
    matchLabels:
      app: flannel
      k8s-app: flannel
  template:
    metadata:
      labels:
        app: flannel
        k8s-app: flannel
        tier: node
    spec:
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
            - matchExpressions:
              - key: kubernetes.io/os
                operator: In
                values:
                - linux
      containers:
      - args:
        - --ip-masq
        - --kube-subnet-mgr
        command:
        - /opt/bin/flanneld
        env:
        - name: POD_NAME
          valueFrom:
            fieldRef:
              fieldPath: metadata.name
        - name: POD_NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
        - name: EVENT_QUEUE_DEPTH
          value: "5000"
        image: docker.io/flannel/flannel:v0.22.0
        name: kube-flannel
        resources:
          requests:
            cpu: 100m
            memory: 50Mi
        securityContext:
          capabilities:
            add:
            - NET_ADMIN
            - NET_RAW
          privileged: false
        volumeMounts:
        - mountPath: /run/flannel
          name: run
        - mountPath: /etc/kube-flannel/
          name: flannel-cfg
        - mountPath: /run/xtables.lock
          name: xtables-lock
      hostNetwork: true
      initContainers:
      - args:
        - -f
        - /flannel
        - /opt/cni/bin/flannel
        command:
        - cp
        image: docker.io/flannel/flannel-cni-plugin:v1.1.2
        name: install-cni-plugin
        volumeMounts:
        - mountPath: /opt/cni/bin
          name: cni-plugin
      - args:
        - -f
        - /etc/kube-flannel/cni-conf.json
        - /etc/cni/net.d/10-flannel.conflist
        command:
        - cp
        image: docker.io/flannel/flannel:v0.22.0
        name: install-cni
        volumeMounts:
        - mountPath: /etc/cni/net.d
          name: cni
        - mountPath: /etc/kube-flannel/
          name: flannel-cfg
      priorityClassName: system-node-critical
      serviceAccountName: flannel
      tolerations:
      - effect: NoSchedule
        operator: Exists
      volumes:
      - hostPath:
          path: /run/flannel
        name: run
      - hostPath:
          path: /opt/cni/bin
        name: cni-plugin
      - hostPath:
          path: /etc/cni/net.d
        name: cni
      - configMap:
          name: kube-flannel-cfg
        name: flannel-cfg
      - hostPath:
          path: /run/xtables.lock
          type: FileOrCreate
        name: xtables-lock