2、Kubernetes 安装集群

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本文详细介绍如何使用kubeadm工具快速搭建Kubernetes集群，包括配置修改、镜像拉取、主节点与从节点的安装步骤，以及网络插件的安装。

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概述

kubeadm 是 kubernetes 的集群安装工具，能够快速安装 kubernetes 集群，安装 kubernetes 主要是安装它的各个镜像，而 kubeadm 已经为我们集成好了运行 kubernetes 所需的基本镜像。但由于国内的网络原因，在搭建环境时，无法拉取到这些镜像。此时我们只需要修改为阿里云提供的镜像服务即可解决该问题。

创建并修改配置

在/usr/local/ 目录下

mkdir -p kubernetes/cluser

执行下面命令

# 导出配置文件
kubeadm config print init-defaults --kubeconfig ClusterConfiguration > kubeadm.yml

查看生成的kubeadm.yml 如下

apiVersion: kubeadm.k8s.io/v1beta2
bootstrapTokens:
- groups:
  - system:bootstrappers:kubeadm:default-node-token
  token: abcdef.0123456789abcdef
  ttl: 24h0m0s
  usages:
  - signing
  - authentication
kind: InitConfiguration
localAPIEndpoint:
  # 修改为主节点 IP
  advertiseAddress: 192.168.40.150
  bindPort: 6443
nodeRegistration:
  criSocket: /var/run/dockershim.sock
  name: kubernetes-master
  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
# 国内不能访问 Google，修改为阿里云
imageRepository: registry.aliyuncs.com/google_containers
kind: ClusterConfiguration
# 修改版本号
kubernetesVersion: v1.15.0
networking:
  dnsDomain: cluster.local
  # 配置 POD 所在网段为我们虚拟机不重叠的网段（这里用的是 Flannel 默认网段）
  podSubnet: "10.244.0.0/16"
  serviceSubnet: 10.96.0.0/12
scheduler: {}

查看所需镜像

kubeadm config images list --config kubeadm.yml
# 输出如下
registry.aliyuncs.com/google_containers/kube-apiserver:v1.15.0
registry.aliyuncs.com/google_containers/kube-controller-manager:v1.15.0
registry.aliyuncs.com/google_containers/kube-scheduler:v1.15.0
registry.aliyuncs.com/google_containers/kube-proxy:v1.15.0
registry.aliyuncs.com/google_containers/pause:3.1
registry.aliyuncs.com/google_containers/etcd:3.3.10
registry.aliyuncs.com/google_containers/coredns:1.3.1

拉取所需镜像

需要费一些时间，耐心等待

kubeadm config images pull --config kubeadm.yml
# 输出如下
[config/images] Pulled registry.aliyuncs.com/google_containers/kube-apiserver:v1.15.0
[config/images] Pulled registry.aliyuncs.com/google_containers/kube-controller-manager:v1.15.0
[config/images] Pulled registry.aliyuncs.com/google_containers/kube-scheduler:v1.15.0
[config/images] Pulled registry.aliyuncs.com/google_containers/kube-proxy:v1.15.0
[config/images] Pulled registry.aliyuncs.com/google_containers/pause:3.1
[config/images] Pulled registry.aliyuncs.com/google_containers/etcd:3.3.10
[config/images] Pulled registry.aliyuncs.com/google_containers/coredns:1.3.1

安装主节点

kubeadm init --config=kubeadm.yml --upload-certs | tee kubeadm-init.log
# 输出如下
Flag --experimental-upload-certs has been deprecated, use --upload-certs instead
[init] Using Kubernetes version: v1.15.0
[preflight] Running pre-flight checks
        [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] 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-kubelet-client" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [kubernetes-master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.40.150]
[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 [kubernetes-master localhost] and IPs [192.168.40.150 127.0.0.1 ::1]
[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 [kubernetes-master localhost] and IPs [192.168.40.150 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-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 23.006217 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] Storing the certificates in Secret "kubeadm-certs" in the "kube-system" Namespace
[upload-certs] Using certificate key:
4a351218cf34c15b04b08b7d916c27a625418145d8d3b281ec125fd2b2ac7ab5
[mark-control-plane] Marking the node kubernetes-master as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node kubernetes-master as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: abcdef.0123456789abcdef
[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 192.168.40.150:6443 --token abcdef.0123456789abcdef \
    --discovery-token-ca-cert-hash sha256:f0759e0d352c1a5de4444782b4a676460b2ea7a2876fa0accab572b8629b72c8

配置 kubectl

mkdir -p $HOME/.kube
cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
# 非 ROOT 用户执行
chown $(id -u):$(id -g) $HOME/.kube/config

验证是否成功

kubectl get node
# 输出如下
NAME                STATUS     ROLES    AGE     VERSION
kubernetes-master   NotReady   master   4m38s   v1.15.0

安装从节点

将 Node 节点加入到集群中很简单，只需要在 Node 服务器上安装 kubeadm，kubectl，kubelet 三个工具，然后使用 kubeadm join 命令加入即可

kubeadm join 192.168.40.150:6443 --token abcdef.0123456789abcdef \
    --discovery-token-ca-cert-hash sha256:f0759e0d352c1a5de4444782b4a676460b2ea7a2876fa0accab572b8629b72c8
# 输出如下
[preflight] Running pre-flight checks
        [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] Downloading configuration for the kubelet from the "kubelet-config-1.15" ConfigMap in the kube-system namespace
[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] Activating the kubelet service
[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.

验证是否成功

回到 Master 主节点查看是否安装成功

注意：如果 Node 节点加入 Master 时配置有问题可以在 Node 节点上使用 kubeadm reset 重置配置再使用 kubeadm join 命令重新加入即可。希望在 master 节点删除 node ，可以使用 kubectl delete nodes 删除。

kubectl get node
# 输出如下
NAME                 STATUS     ROLES    AGE   VERSION
kubernetes-master    NotReady   master   20m   v1.15.0
kubernetes-node-01   NotReady   <none>   16s   v1.15.0
kubernetes-node-02   NotReady   <none>   6s    v1.15.0

查看 Pod 状态

coredns 尚未运行，此时我们还需要安装网络插件

kubectl get pod -n kube-system -o wide
# 输出如下
NAME                                        READY   STATUS    RESTARTS   AGE     IP                NODE                 NOMINATED NODE   READINESS GATES
coredns-bccdc95cf-9s4bm                     0/1     Pending   0          24m     <none>            <none>               <none>           <none>
coredns-bccdc95cf-s8ggd                     0/1     Pending   0          24m     <none>            <none>               <none>           <none>
etcd-kubernetes-master                      1/1     Running   0          24m     192.168.141.110   kubernetes-master    <none>           <none>
kube-apiserver-kubernetes-master            1/1     Running   0          24m     192.168.141.110   kubernetes-master    <none>           <none>
kube-controller-manager-kubernetes-master   1/1     Running   0          23m     192.168.141.110   kubernetes-master    <none>           <none>
kube-proxy-8s87d                            1/1     Running   0          4m56s   192.168.141.120   kubernetes-node-01   <none>           <none>
kube-proxy-cbnlb                            1/1     Running   0          4m46s   192.168.141.121   kubernetes-node-02   <none>           <none>
kube-proxy-vwhxj                            1/1     Running   0          24m     192.168.141.110   kubernetes-master    <none>           <none>
kube-scheduler-kubernetes-master            1/1     Running   0          24m     192.168.141.110   kubernetes-master    <none>           <none>