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一键部署利器 Kubeadm 搭建 Kubernetes

2021-05-06  本文已影响0人  读书学习看报

准备工作

阿里云买两台 ECS，至少 2 核 4G 要求，用来临时学习，一周时间即可，便宜点的差不多单台一周 30 元左右。

安装 Docker

sudo yum install -y yum-utils
sudo yum-config-manager \
    --add-repo \
    https://download.docker.com/linux/centos/docker-ce.repo
sudo yum install docker-ce docker-ce-cli containerd.io
sudo systemctl start docker

docker -v

加载 Kubernetes 所需镜像

由于网络问题，这里使用阿里云镜像下载，然后利用 docker tag 来重新命名为 Kubernetes 默认镜像名称。

docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/kube-apiserver:v1.19.0
docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/kube-controller-manager:v1.19.0
docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/kube-scheduler:v1.19.0
docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/kube-proxy:v1.19.0
docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/pause:3.2
docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:3.4.9-1
docker pull registry.cn-hangzhou.aliyuncs.com/google_containers/coredns:1.7.0

docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/kube-apiserver:v1.19.0 k8s.gcr.io/kube-apiserver:v1.19.0
docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/kube-controller-manager:v1.19.0 k8s.gcr.io/kube-controller-manager:v1.19.0
docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/kube-scheduler:v1.19.0 k8s.gcr.io/kube-scheduler:v1.19.0
docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/kube-proxy:v1.19.0 k8s.gcr.io/kube-proxy:v1.19.0
docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/pause:3.2 k8s.gcr.io/pause:3.2
docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/etcd:3.4.9-1 k8s.gcr.io/etcd:3.4.9-1
docker tag registry.cn-hangzhou.aliyuncs.com/google_containers/coredns:1.7.0 k8s.gcr.io/coredns:1.7.0

安装 kubeadm

kubeadm 是 Kubernetes 的一键部署利器，方便用来学习，首先需要在两个节点都安装 kubeadm、kubectl、kubelet 这三个二进制文件，由于上面下载的镜像是 v1.19.0 版本的，所以安装时请务必指定版本号。

# 添加阿里云仓库
cat <<EOF | sudo tee /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

# Set SELinux in permissive mode (effectively disabling it)
sudo setenforce 0
sudo sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config

# 这里切记指定版本号
sudo yum install -y kubelet-1.19.0 kubeadm-1.19.0 kubectl-1.19.0 --disableexcludes=kubernetes
sudo systemctl enable --now kubelet

安装成功后，可以查看其版本信息：

[root@kube002 ~]# kubeadm version
kubeadm version: &version.Info{Major:"1", Minor:"19", GitVersion:"v1.19.0", GitCommit:"e19964183377d0ec2052d1f1fa930c4d7575bd50", GitTreeState:"clean", BuildDate:"2020-08-26T14:28:32Z", GoVersion:"go1.15", Compiler:"gc", Platform:"linux/amd64"}

[root@kube002 ~]# kubectl version
Client Version: version.Info{Major:"1", Minor:"19", GitVersion:"v1.19.0", GitCommit:"e19964183377d0ec2052d1f1fa930c4d7575bd50", GitTreeState:"clean", BuildDate:"2020-08-26T14:30:33Z", GoVersion:"go1.15", Compiler:"gc", Platform:"linux/amd64"}

kubeadm init

使用 kubeadm init 来部署 Master 节点，执行后，会首先做一系列的检查工作 Running pre-flight checks。

kubeadm init --kubernetes-version=v1.19.0 --pod-network-cidr=10.244.0.0/16 --service-cidr=10.96.0.0/12

[init] Using Kubernetes version: v1.19.0
[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 configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Starting the kubelet
[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
......
[mark-control-plane] Marking the node kube001 as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node kube001 as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
......
[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
[kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key
[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 172.24.251.196:6443 --token gopfsz.5r5pp10ppen86xrv \
    --discovery-token-ca-cert-hash sha256:ea1f97ae7ff9364f2efbc4aad55d3e084a511f05ce46e2c730880c723b72ecea

大家可以详细的去看下 kubeadm init 安装时输出的日志，里面有非常多的重要信息。

其中下面这段信息会在部署 Worker 节点时用到。

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

kubeadm join

kubeadm init 会生成一个 token，可以在任意一台安装了 kubeadm、kubelet、kubectl 的机器上执行 kubeadm join。作为 Worker 节点加入 Kubernetes 集群。

kubeadm join 172.24.251.196:6443 --token gopfsz.5r5pp10ppen86xrv \
    --discovery-token-ca-cert-hash sha256:ea1f97ae7ff9364f2efbc4aad55d3e084a511f05ce46e2c730880c723b72ecea

>     --discovery-token-ca-cert-hash sha256:ea1f97ae7ff9364f2efbc4aad55d3e084a511f05ce46e2c730880c723b72ecea
[preflight] Running pre-flight checks
    [WARNING Service-Docker]: docker service is not enabled, please run 'systemctl enable docker.service'
    [WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[kubelet-start] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet-start] Starting the kubelet
[kubelet-start] Waiting for the kubelet to perform the TLS Bootstrap...

This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.

Run 'kubectl get nodes' on the control-plane to see this node join the cluster.

将 master 节点上的 /etc/kubernetes/admin.conf 文件 copy 至 Worker 节点的相同目录下，然后执行一下命令：

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

kube-apiserver.yaml

以上执行完成后，在 Worker 节点运行 kubectl get nodes 时会报错，此时需要去 master 节点修改 apiserver 的参数 --insecure-port，绕过身份认证和鉴权模块，默认值为 0。

spec:
  containers:
  - command:
    - kube-apiserver
    - --advertise-address=172.24.251.196
    - --allow-privileged=true
    - --authorization-mode=Node,RBAC
    - --client-ca-file=/etc/kubernetes/pki/ca.crt
    - --enable-admission-plugins=NodeRestriction
    - --enable-bootstrap-token-auth=true
    - --etcd-cafile=/etc/kubernetes/pki/etcd/ca.crt
    - --etcd-certfile=/etc/kubernetes/pki/apiserver-etcd-client.crt
    - --etcd-keyfile=/etc/kubernetes/pki/apiserver-etcd-client.key
    - --etcd-servers=https://127.0.0.1:2379
    - --insecure-port=8080

kubectl get nodes

kubectl get nodes 获取 Node 节点信息，会发现其状态都处于 NotReady：

[root@kube002 ~]# kubectl get nodes
NAME      STATUS     ROLES    AGE     VERSION
kube001   NotReady   master   9m13s   v1.19.0
kube002   NotReady   <none>   4m52s   v1.19.0

通过 kubectl describe node kube001 会出现如下的错误信息提示，意思是 CNI 插件还未安装，这里选择安装的网络插件是 Flannel。

KubeletNotReady 
runtime network not ready: 
NetworkReady=false 
reason:NetworkPluginNotReady message:docker: network plugin is not ready: cni config uninitialized

安装 Flannel 网络插件

网络可能存在 DNS 污染，如果访问不了下面的网址，可以前去修改 hosts 配置，执行如下命令即可：

cat >> /etc/hosts <<EOF
199.232.96.133 raw.githubusercontent.com
EOF

由于 Kubernetes 一切皆容器的设计，所以插件的安装也非常方便：

kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml

[root@kube001 ~]# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/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 created

执行成功后，可在任意节点执行如下命令，看到 Matser 节点和 Worker 节点都处于 Ready 状态了。

[root@kube002 ~]# kubectl get nodes
NAME      STATUS   ROLES    AGE   VERSION
kube001   Ready    master   15m   v1.19.0
kube002   Ready    <none>   11m   v1.19.0

kubectl taint nodes

由于 Master 节点默认是不允许被调度运行创建 Pod 的，其功能是通过打标签实现的，现在测试的话，可以允许在 Master 上创建 Pod，所以可以执行以下命令去除 Master 节点的污点。

kubectl taint nodes --all node-role.kubernetes.io/master-

安装 Dashboard

上面就已经成功的把 Kubernetes 平台安装成功了，大家可以去查询一些基础命令去执行下，看下详细的输出；下面来安装下 Kubernetes 的 UI 控制界面，首先是把 Dashboard 的 YML 文件下载到本地，因为要对其中的端口映射，和权限信息进行修改。

curl https://raw.githubusercontent.com/kubernetes/dashboard/v2.2.0/aio/deploy/recommended.yaml >> /opt/dashboard.yml

具体修改的地方如下，大家可以搜索到替换，第一处是为了能在外网访问 Dashboard UI，所以要将 Service 的 type 修改为 NodePort，然后指定要暴露的端口 nodePort: 30000。（别忘记去给 ECS 添加安全组端口）

kind: Service
apiVersion: v1
metadata:
  labels:
    k8s-app: kubernetes-dashboard
  name: kubernetes-dashboard
  namespace: kubernetes-dashboard
spec:
  ports:
    - port: 443
      targetPort: 8443
      nodePort: 30000
  selector:
    k8s-app: kubernetes-dashboard
  type: NodePort

第二处是修改默认的用户 kubernetes-dashboard 的角色，这里直接使用 Kubernetes 内置的最大管理员，生产中切记不可这样做，需要更细粒度的去控制每个账号的权限。

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: kubernetes-dashboard
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  # k8s 默认的
  name: cluster-admin
subjects:
  - kind: ServiceAccount
    name: kubernetes-dashboard
    namespace: kubernetes-dashboard

然后通过 kubectl apply -f 创建并运行：

[root@kube002 ~]# kubectl apply -f /opt/dashboard.yml 
namespace/kubernetes-dashboard created
serviceaccount/kubernetes-dashboard created
service/kubernetes-dashboard created
secret/kubernetes-dashboard-certs created
secret/kubernetes-dashboard-csrf created
secret/kubernetes-dashboard-key-holder created
configmap/kubernetes-dashboard-settings created
role.rbac.authorization.k8s.io/kubernetes-dashboard created
clusterrole.rbac.authorization.k8s.io/kubernetes-dashboard created
rolebinding.rbac.authorization.k8s.io/kubernetes-dashboard created
clusterrolebinding.rbac.authorization.k8s.io/kubernetes-dashboard created
deployment.apps/kubernetes-dashboard created
service/dashboard-metrics-scraper created
deployment.apps/dashboard-metrics-scraper created

获取登录 Token

https://ip:30000 注意要是用 https 访问

每个账号都会生成对应的 token，用来授权登录：

[root@kube002 ~]# kubectl get secret -n kubernetes-dashboard
NAME                               TYPE                                  DATA   AGE
default-token-fl6wt                kubernetes.io/service-account-token   3      72s
kubernetes-dashboard-certs         Opaque                                0      72s
kubernetes-dashboard-csrf          Opaque                                1      72s
kubernetes-dashboard-key-holder    Opaque                                2      72s
kubernetes-dashboard-token-qsktp   kubernetes.io/service-account-token   3      72s

查看 token：

[root@kube002 ~]# kubectl describe secret kubernetes-dashboard-token-qsktp -n kubernetes-dashboard
Name:         kubernetes-dashboard-token-qsktp
Namespace:    kubernetes-dashboard
Labels:       <none>
Annotations:  kubernetes.io/service-account.name: kubernetes-dashboard
              kubernetes.io/service-account.uid: 8444c0a6-3712-4c33-a926-6ddee6f6dfad

Type:  kubernetes.io/service-account-token

Data
====
ca.crt:     1066 bytes
namespace:  20 bytes
token:      eyJhbGciOiJSUzI1NiIsImtpZCI6ImQ5NlJoSHpjSEwtZ2djVU1Idy05YTh2UFpmTE03bzBsQ29scGJ6cXRxbEUifQ.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.nIp2VQYAup13_klFqgFaBVaekH5WCQ2FSZY4qaP5aggw5UrYlCXfsgMnam_TJd5m5J0ZfOeGOpm3HfhcF3PglZvdZwiR5QAeBolQLFyr38MSavyiZ15z3m7iLHEnaDXFPYc4Zz9lrRJDMrmHDSz7Kpu5Ncjwxcm-tIPsn6ymtHltkkiN88qYMKJ1PplCajE-pOkTJUg5Vybb11ZDTxEkEKWP44T6-WNLNa-jA9RsHFu7p7kXfwnnhGjEE0V0CS3hpXQK4RusWsUh-WFh1zCWc5-Vx8bGOA_UeTcuma2s8do9lt7jx_Bc94JzCadyQtRSbSVpY2Ets4zXl7A29DZtrw

登录成功后的界面：

卸载重建集群

kubeadm reset
rm -rf $HOME/.kube

~ END ~。

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