K8S（一）-搭建k8s集群

K8S（一）-搭建k8s集群
集群组成：

master 主节点，不需要太多，高可用
node 真正提供工作的节点，也叫worker节点，为了运行容器的节点

master节点主要由四个模块组成：
- APIServer 提供了资源操作的唯一入口，任何对资源进行增删改查的操作都要交给APIServer处理后再提交给etcd。kubectl就是对api server的调用。
- scheduler 负责资源的调度，按照预定的调度策略将Pod调度到相应的机器上；
- controller manager 负责维护集群的状态，比如故障检测、自动扩展、滚动更新等；
- etcd 是一个高可用的kv存储系统，Kubernetes使用它来存储各个资源的状态，支持Restful的API。
node节点主要由三个模块组成：
- Container runtime 容器运行环境，常用docker容器
- kubelet 负责维护容器的生命周期，管理pods和pods上面的容器
- kube-proxy 负责为Service提供cluster内部的服务发现和负载均衡
安装部署

方法1：将k8s所有组件都运行为系统级的守护进程，包括master节点上的4个组件和node节点上的3个组件。全部需要手动安装，包括证书等，安装过程较复杂。

方法2：使用kubeadm工具来部署，把k8s的组件运行为pod：master的4个组件全部运行为pod，node节点上的kube-proxy也运行为pod，需要注意这里的pod都是static pod。

这里采用方法2来安装, kubeadm https://github.com/kubernetes/kubeadm

master&slave: 安装kubeadm，docker, kubectl, flannel(支持pod间互相通信)
master : kubeadm init
slave: kubeadm join

1.时间同步，关闭防火墙。

2.安装docker。wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo

2.配置kubernetes yum源
```
[kubernetes]
name=kubernetes Repo
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/
enabled=1
gpgcheck=1
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
```
wget https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
rpm --import rpm-package-key.gpg

4.安装所需组件
yum install kubelet-1.14.3 kubeadm-1.14.3 kubectl-1.14.3 docker-ce-18.09*
```
vim /etc/docker/daemon.json

{
"registry-mirrors": ["https://3s01e0d2.mirror.aliyuncs.com"],
"exec-opts": ["native.cgroupdriver=systemd"],
"log-driver": "json-file",
"log-opts": {
"max-size": "100m"
},
"storage-driver": "overlay2",
"storage-opts": [
"overlay2.override_kernel_check=true"
]
}
```
systemctl start docker

systemctl enable docker

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

忽略swap
vim /etc/sysconfig/kubelet
[root@heaven00 ~]# cat /etc/sysconfig/kubelet
KUBELET_EXTRA_ARGS="--fail-swap-on=false"

master节点

初始化master节点
```
# kubeadm init  --kubernetes-version=v1.14.3 --pod-network-cidr=10.244.0.0/16 --service-cidr=10.96.0.0/12 --ignore-preflight-errors=swap
[init] using Kubernetes version: v1.14.3
[preflight] running pre-flight checks
    [WARNING KubernetesVersion]: kubernetes version is greater than kubeadm version. Please consider to upgrade kubeadm. kubernetes version: beadm version: 1.11.x

[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy

Your Kubernetes master 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/

You can now join any number of machines by running the following on each node
as root:

  kubeadm join 172.17.8.128:6443 --token 825yrh.qe2kpku40dwcwusb --discovery-token-ca-cert-hash sha256:02b158edd568a75523cb12a1561b65937bcf146319484fd86f88e9
```
```
执行：
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
```
# kubectl get cs

# kubectl get nodes
NAME STATUS ROLES AGE VERSION
master01 NotReady master 164m v1.11.2 #nodes处于NotReady状态，因为缺少网络组件

部署网络组件 flannel
```
# 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-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
```
等待一会儿

docker image ls 看到flannel镜像下载下来

kubectl get pods -n kube-system 查看pods运行在，

才说明flannel安装成功
```
# kubectl get pods -n kube-system
NAME                               READY   STATUS    RESTARTS   AGE
coredns-8686dcc4fd-qg5jz           1/1     Running   0          4m33s
coredns-8686dcc4fd-vx64c           1/1     Running   0          4m33s
etcd-master01                      1/1     Running   0          3m46s
kube-apiserver-master01            1/1     Running   0          3m42s
kube-controller-manager-master01   1/1     Running   0          3m33s
kube-flannel-ds-amd64-5sbrx        1/1     Running   1          2m49s
kube-flannel-ds-amd64-wlr5x        1/1     Running   0          3m34s
kube-proxy-d2pzd                   1/1     Running   0          2m49s
kube-proxy-gpwkg                   1/1     Running   0          4m33s
kube-scheduler-master01            1/1     Running   0          3m49s  
```
再查看 kubectl get nodes 会看到已经ready
```
# kubectl get nodes
NAME            STATUS   ROLES    AGE     VERSION
master01        Ready    master   5m52s   v1.14.3
```
# kubelet get ns

node节点

安装组件
```
# yum install kubelet-1.14.3  kubeadm-1.14.3  kubectl-1.14.3 
```
加入集群
```
# kubeadm join 172.17.8.128:6443 --token j1u40p.5is2liahibv1gwgk  --discovery-token-ca-cert-hash sha256:51579863a2ff093f730c0552c13c44ea87e270064a7fc9ba5bac069ca47cf2cb 
[preflight] Running pre-flight checks
[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-1.14" 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.
```
node加入集群后 在master上面查看

]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
node01 Ready <none> 3d21h v1.14.3
master01 Ready master 3d21h v1.14.3

kubectl get pods -n kube-system -o wide 可以查看集群内所有的pods，包括node节点的

报错1：

启动docker时报错：Error starting daemon: Error initializing network controller: list bridge addresses failed: no available network

解决：需要手动添加下docker0网桥：,注意不要跟虚拟机在同一网段

brctl addbr docker0
ip addr add 172.17.0.1/16 dev docker0
ip link set dev docker0 up
systemctl restart docker

报错2：初始化kubeadm时

[preflight] Some fatal errors occurred:
[ERROR ImagePull]: failed to pull image [k8s.gcr.io/kube-apiserver-amd64:v1.14.3]: exit status 1
[ERROR ImagePull]: failed to pull image [k8s.gcr.io/kube-controller-manager-amd64:v1.14.3]: exit status 1
[ERROR ImagePull]: failed to pull image [k8s.gcr.io/kube-scheduler-amd64:v1.14.3]: exit status 1
[ERROR ImagePull]: failed to pull image [k8s.gcr.io/kube-proxy-amd64:v1.14.3]: exit status 1
[ERROR ImagePull]: failed to pull image [k8s.gcr.io/pause:3.1]: exit status 1
[ERROR ImagePull]: failed to pull image [k8s.gcr.io/etcd-amd64:3.2.18]: exit status 1
[ERROR ImagePull]: failed to pull image [k8s.gcr.io/coredns:1.1.3]: exit status 1
[preflight] If you know what you are doing, you can make a check non-fatal with `--ignore-preflight-errors=...`

解决方法：
通过别的镜像仓库，先将镜像下载下来然后再修改成k8s.gcr.io对应的tag
docker pull mirrorgooglecontainers/kube-apiserver-amd64:v1.14.3
docker pull mirrorgooglecontainers/kube-controller-manager-amd64:v1.14.3
docker pull mirrorgooglecontainers/kube-scheduler-amd64:v1.14.3
docker pull mirrorgooglecontainers/kube-proxy-amd64:v1.14.3
docker pull mirrorgooglecontainers/pause:3.1
docker pull mirrorgooglecontainers/etcd-amd64:3.2.18
docker pull coredns/coredns:1.3.1

修改tag：

docker tag mirrorgooglecontainers/kube-apiserver-amd64:v1.14.3 k8s.gcr.io/kube-apiserver:v1.14.3
docker tag mirrorgooglecontainers/kube-controller-manager-amd64:v1.14.3 k8s.gcr.io/kube-controller-manager:v1.14.3
docker tag mirrorgooglecontainers/kube-scheduler-amd64:v1.14.3 k8s.gcr.io/kube-scheduler:v1.14.3
docker tag mirrorgooglecontainers/etcd-amd64:3.2.18 k8s.gcr.io/etcd:3.3.10
docker tag mirrorgooglecontainers/kube-proxy-amd64:v1.14.3 k8s.gcr.io/kube-proxy:v1.14.3
docker tag coredns/coredns:1.3.1 k8s.gcr.io/coredns:1.3.1
docker tag mirrorgooglecontainers/pause:3.1 k8s.gcr.io/pause:3.1

报错3： node 执行 kubeadm join 加入集群时报错：

报错1：configmaps "kubelet-config-1.11" is forbidden: User "system:bootstrap:wdchig" cannot get resource "configmaps" in API group "" in the namespacetem"
原因：版本问题，当前版本为1.11.2 。需要升级kubelet和kubeadm。按照上面的安装步骤来，安装的时候指定版本即可。

报错2：couldn't validate the identity of the API Server: expected a 32 byte SHA-256 hash, found 29 bytes

　　原因：kubeadm init生成的token有效期只有1天

　　解决方法：

　　在master节点检查token是否有效

　　master # kubeadm token list 查看
　　master# kubeadm token create --print-join-command 生成新的token和命令。然后在node重新执行
报错4：重新执行初始化的时候报错： error marking master: timed out waiting for the condition

解决：
```
# kubeadm reset -f && rm -rf /etc/kubernetes/
```
清理集群数据然后再 kubeadm init --kubernetes-version=v1.14.3 --pod-network-cidr=10.244.0.0/16 --service-cidr=10.96.0.0/12 --ignore-preflight-errors=Swap

报错5： master节点显示master状态为NotRedy。 coredns CrashLoopBackOff

   在网上找到方法, 说是CoreDNS启动后会通过宿主机的resolv.conf文件去获取上游DNS的信息，如果这个时候获取的DNS的服务器是本地地址的话，就会出现环路，从而被环路识别器识别出来。

解决：查看机器 /etc/resolv.conf

nameserver 127.0.0.1 修改为  nameserver 114.114.114.114 ，重新初始化后解决

报错6： node节点join时正常，但是在master查看时node显示NotReady状态。

# kubectl get nodes
NAME STATUS ROLES AGE VERSION
node01 NotReady <none> 3d20h v1.14.3
master01 Ready master 3d21h v1.14.3

# kubectl describe pod kube-proxy-l6pwk -n kube-system 查看pod详细信息

# kubectl -n kube-system logs  kube-proxy-l6pwk   查看日志

Warning FailedCreatePodSandBox 60m (x1999 over 3d20h) kubelet, node01 Failed create pod sandbox: rpc error: code = Unknown desc = failed pulling image "k8s.gcr.io/pause:3.1": Error response from daemon: Get https://k8s.gcr.io/v1/_ping: dial tcp 74.125.204.82:443: getsockopt: connection timed out
通过手动拉取镜像并打tag。解决。

报错7：加入集群后node状态为NotReady
journalctl -f -u kubelet 可在节点机器查看kubelet的输出日志信息
E0528 18:56:54.890957 24778 kubelet.go:2170] Container runtime network not ready: NetworkReady=false reason:NetworkPluginNotReady message:docker: network plugin is not ready: cni config uninitialized
docker pull quay.io/coreos/flannel:v0.12.0-amd64
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原文地址：https://www.cnblogs.com/xiaobaozi-95/p/11526326.html

K8S（一）-搭建k8s集群

master节点

node节点