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使用kubeadm部署集群

1、配置kubernetes源

[root@k8s-master ~]# cd /etc/yum.repos.d/

配置阿里云的源：https://opsx.alibaba.com/mirror

[root@k8s-master yum.repos.d]# wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo　　#配置dokcer源

[root@k8s-master ~]# cat <<EOF > /etc/yum.repos.d/kubernetes.repo　　#配置kubernetes源
> [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

[root@k8s-master yum.repos.d]# yum repolist #查看可用源

将源拷贝到node01和node02节点

[root@k8s-master yum.repos.d]# scp kubernetes.repo docker-ce.repo k8s-node1:/etc/yum.repos.d/
kubernetes.repo                         100%  276   276.1KB/s   00:00    
docker-ce.repo                          100% 2640     1.7MB/s   00:00    
[root@k8s-master yum.repos.d]# scp kubernetes.repo docker-ce.repo k8s-node2:/etc/yum.repos.d/
kubernetes.repo                         100%  276   226.9KB/s   00:00    
docker-ce.repo                          100% 2640     1.7MB/s   00:00    

2、Master节点安装docker、kubelet、kubeadm、还有命令行工具kubectl

[root@k8s-master yum.repos.d]# yum install -y docker-ce kubelet kubeadm kubectl 
[root@k8s-master ~]# systemctl start docker
[root@k8s-master ~]# systemctl enable docker

启动docker，docker需要到自动到docker仓库中所依赖的镜像文件，这些镜像文件会因为在国外仓库而下载无法完成，所以最好预先下载镜像文件，kubeadm也可以支持本地私有仓库进行获取镜像文件。

3、预先下载镜像

在master节点上使用docker pull拉取镜像，再通过tag打标签
docker pull xiyangxixia/k8s-proxy-amd64:v1.11.1
docker tag xiyangxixia/k8s-proxy-amd64:v1.11.1 k8s.gcr.io/kube-proxy-amd64:v1.11.1
docker pull xiyangxixia/k8s-scheduler:v1.11.1
docker tag xiyangxixia/k8s-scheduler:v1.11.1 k8s.gcr.io/kube-scheduler-amd64:v1.11.1
docker pull xiyangxixia/k8s-controller-manager:v1.11.1
docker tag xiyangxixia/k8s-controller-manager:v1.11.1 k8s.gcr.io/kube-controller-manager-amd64:v1.11.1
docker pull xiyangxixia/k8s-apiserver-amd64:v1.11.1
docker tag xiyangxixia/k8s-apiserver-amd64:v1.11.1 k8s.gcr.io/kube-apiserver-amd64:v1.11.1
docker pull xiyangxixia/k8s-etcd:3.2.18
docker tag xiyangxixia/k8s-etcd:3.2.18 k8s.gcr.io/etcd-amd64:3.2.18
docker pull xiyangxixia/k8s-coredns:1.1.3
docker tag xiyangxixia/k8s-coredns:1.1.3 k8s.gcr.io/coredns:1.1.3
docker pull xiyangxixia/k8s-pause:3.1
docker tag xiyangxixia/k8s-pause:3.1 k8s.gcr.io/pause:3.1
docker pull xiyangxixia/k8s-flannel:v0.10.0-s390x
docker tag xiyangxixia/k8s-flannel:v0.10.0-s390x quay.io/coreos/flannel:v0.10.0-s390x
docker pull xiyangxixia/k8s-flannel:v0.10.0-ppc64le
docker tag xiyangxixia/k8s-flannel:v0.10.0-ppc64le quay.io/coreos/flannel:v0.10.0-ppc64l
docker pull xiyangxixia/k8s-flannel:v0.10.0-arm
docker tag xiyangxixia/k8s-flannel:v0.10.0-arm quay.io/coreos/flannel:v0.10.0-arm
docker pull xiyangxixia/k8s-flannel:v0.10.0-amd64
docker tag xiyangxixia/k8s-flannel:v0.10.0-amd64 quay.io/coreos/flannel:v0.10.0-amd64

node节点上拉取的镜像

docker pull xiyangxixia/k8s-pause:3.1
docker tag xiyangxixia/k8s-pause:3.1 k8s.gcr.io/pause:3.1
docker pull xiyangxixia/k8s-proxy-amd64:v1.11.1
docker tag xiyangxixia/k8s-proxy-amd64:v1.11.1 k8s.gcr.io/kube-proxy-amd64:v1.11.1
docker pull xiyangxixia/k8s-flannel:v0.10.0-amd64
docker tag xiyangxixia/k8s-flannel:v0.10.0-amd64 quay.io/coreos/flannel:v0.10.0-amd64

4、部署kubernetes的Master节点

[root@k8s-master ~]# vim /etc/sysconfig/kubelet 　　#修改kubelet禁止提示swap警告
KUBELET_EXTRA_ARGS="--fail-swap-on=false" #如果配置了swap不然提示出错信息
更改kubelet配置，不提示swap警告信息，最好关闭swap

[root@k8s-master ~]# swapoff -a　　#关闭swap

[root@k8s-master ~]# kubeadm init --kubernetes-version=v1.11.1 --pod-network-cidr=10.244.0.0/16 --service-cidr=10.96.0.0/12 --ignore-preflight-errors=Swap   　　#初始化 
[init] using Kubernetes version: v1.11.1
[preflight] running pre-flight checks
I0821 18:14:22.223765   18053 kernel_validator.go:81] Validating kernel version
I0821 18:14:22.223894   18053 kernel_validator.go:96] Validating kernel config
    [WARNING SystemVerification]: docker version is greater than the most recently validated version. Docker version: 18.06.0-ce. Max validated version: 17.03
[preflight/images] Pulling images required for setting up a Kubernetes cluster
[preflight/images] This might take a minute or two, depending on the speed of your internet connection
[preflight/images] You can also perform this action in beforehand using ‘kubeadm config images pull‘
[kubelet] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[preflight] Activating the kubelet service
[certificates] Generated ca certificate and key.
[certificates] Generated apiserver certificate and key.
[certificates] apiserver serving cert is signed for DNS names [k8s-master kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.56.11]
[certificates] Generated apiserver-kubelet-client certificate and key.
[certificates] Generated sa key and public key.
[certificates] Generated front-proxy-ca certificate and key.
[certificates] Generated front-proxy-client certificate and key.
[certificates] Generated etcd/ca certificate and key.
[certificates] Generated etcd/server certificate and key.
[certificates] etcd/server serving cert is signed for DNS names [k8s-master localhost] and IPs [127.0.0.1 ::1]
[certificates] Generated etcd/peer certificate and key.
[certificates] etcd/peer serving cert is signed for DNS names [k8s-master localhost] and IPs [192.168.56.11 127.0.0.1 ::1]
[certificates] Generated etcd/healthcheck-client certificate and key.
[certificates] Generated apiserver-etcd-client certificate and key.
[certificates] valid certificates and keys now exist in "/etc/kubernetes/pki"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/admin.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/kubelet.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/controller-manager.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/scheduler.conf"
[controlplane] wrote Static Pod manifest for component kube-apiserver to "/etc/kubernetes/manifests/kube-apiserver.yaml"
[controlplane] wrote Static Pod manifest for component kube-controller-manager to "/etc/kubernetes/manifests/kube-controller-manager.yaml"
[controlplane] wrote Static Pod manifest for component kube-scheduler to "/etc/kubernetes/manifests/kube-scheduler.yaml"
[etcd] Wrote Static Pod manifest for a local etcd instance to "/etc/kubernetes/manifests/etcd.yaml"
[init] waiting for the kubelet to boot up the control plane as Static Pods from directory "/etc/kubernetes/manifests" 
[init] this might take a minute or longer if the control plane images have to be pulled
[apiclient] All control plane components are healthy after 51.033696 seconds
[uploadconfig] storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.11" in namespace kube-system with the configuration for the kubelets in the cluster
[markmaster] Marking the node k8s-master as master by adding the label "node-role.kubernetes.io/master=‘‘"
[markmaster] Marking the node k8s-master as master by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[patchnode] Uploading the CRI Socket information "/var/run/dockershim.sock" to the Node API object "k8s-master" as an annotation
[bootstraptoken] using token: dx7mko.j2ug1lqjra5bf6p2
[bootstraptoken] configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstraptoken] configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstraptoken] configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[bootstraptoken] creating the "cluster-info" ConfigMap in the "kube-public" namespace
[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 192.168.56.11:6443 --token dx7mko.j2ug1lqjra5bf6p2 --discovery-token-ca-cert-hash sha256:93fe958796db44dcc23764cb8d9b6a2e67bead072e51a3d4d3c2d36b5d1007cf

到了这步就可以完成Kubernetes Master的部署，这个过程需要几分钟。部署完成后，kubeadm会生成一行指令：

kubeadm join 192.168.56.11:6443 --token dx7mko.j2ug1lqjra5bf6p2 --discovery-token-ca-cert-hash sha256:93fe958796db44dcc23764cb8d9b6a2e67bead072e51a3d4d3c2d36b5d1007cf

这个kubeadm join指令，就是用于给这个Master节点添加更多的工作节点（Worker）的命令，后面在部署Worker节点时会用到它，需要记录下来。

此外，kubeadm还会提示我们第一次使用Kubernetes集群所需要配置的命令：

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

? 需要配置这些命令的原因是：Kubernetes集群默认需要加密的方式访问。所以，这几条命令，就是将刚刚生成的Kubernetes集群的安全配置文件，保存到当前用户的.kube目录下，kubectl默认会使用这个目录下的授权信息进行访问Kubernetes集群。如果不那么做的话，我们每次都需要通过export KUBECONFIG环境变量告诉kubectl这个安全配置文件的位置。

如果是使用root用户部署，可以使用export进行定义环境变量

[root@k8s-master ~]# export KUBECONFIG=/etc/kubernetes/admin.conf

到此，集群的初始化已经完成，可以使用kubectl get cs进行查看集群的健康状态信息：

[root@k8s-master ~]# kubectl get cs
NAME                 STATUS    MESSAGE              ERROR
controller-manager   Healthy   ok                   
scheduler            Healthy   ok                   
etcd-0               Healthy   {"health": "true"}
[root@k8s-master ~]# kubectl get node
NAME         STATUS     ROLES     AGE       VERSION
k8s-master   NotReady   master    43m       v1.11.2

从上面的结果可以看到，master的组件controller-manager、scheduler、etcd都处于正常状态。那么apiserver到哪去了？要知道kubectl是通过apiserver进行通信，从而在etcd中获取到集群的状态信息，所以可以获取到集群的状态信息，即表示apiserver是处于正常运行的状态。使用kubectl get node获取节点信息，可以看到master节点的状态是NotReady，这是因为还没有部署好Pod网络。

5、安装网络插件CNI

安装Pod网络插件，用于保证Pod之间的相互通信。在每个集群当中只能有一个Pod网络，在部署flannel之前需要更改的内核参数将桥接的IPv4的流量进行转发给iptables链，这是CNI插件的运行的前提要求。

[root@k8s-master ~]# cat /proc/sys/net/bridge/bridge-nf-call-iptables
1
[root@k8s-master ~]# cat /proc/sys/net/bridge/bridge-nf-call-ip6tables
1
[root@k8s-master ~]# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/c5d10c8/Documentation/kube-flannel.yml
clusterrole.rbac.authorization.k8s.io/flannel created
clusterrolebinding.rbac.authorization.k8s.io/flannel created
serviceaccount/flannel created
configmap/kube-flannel-cfg created
daemonset.extensions/kube-flannel-ds created

[root@k8s-master ~]# kubectl get node　　#再查看master节点的状态信息，就是已经是Ready状态了
NAME         STATUS    ROLES     AGE       VERSION
k8s-master   Ready     master    3h        v1.11.2

至此，Kubernetes的Master节点就已经部署完成，在默认情况下，Kubernetes的Master节点是不能运行用户Pod的，这个属于Kubernetes的污点机制。

6、部署Kubernetes的Worker节点

Kubernetes的Worker节点和Master节点几乎是相同的，它们运行这都是一个kubelet组件。唯一的区别在于kubeadm init的过程中，kubelet启动后，Master节点还会自动运行kube-api-server、kube-scheduler、kube-controller-manager这三个系统Pod。

所以，相比之下，部署Worker节点只需要2步即可完成：

（1）在所有Worker节点上执行"安装kubeadm、kubelet和docker"

（2）执行部署Master节点时生产的kubeadm join指令

[root@k8s-node01 ~]# yum install -y docker kubeadm kubelet
[root@k8s-node01 ~]# systemctl enable dokcer kubelet
[root@k8s-node01 ~]# systemctl start docker

这里需要提前拉取好镜像，如果docker配置了代理另说，按本次方法，提前拉取node节点所需要的镜像。

[root@k8s-node01 ~]# kubeadm join 192.168.56.11:6443 --token dx7mko.j2ug1lqjra5bf6p2 --discovery-token-ca-cert-hash sha256:93fe958796db44dcc23764cb8d9b6a2e67bead072e51a3d4d3c2d36b5d1007cf

[root@k8s-master ~]# kubectl get node　　
NAME         STATUS     ROLES     AGE       VERSION
k8s-master   Ready      master    7h        v1.11.2
k8s-node01   NotReady   <none>    3h        v1.11.2

加入集群后，查看节点状态信息，看到node01节点的状态为NotReady，是因为node01节点上还没有镜像或者是还在拉取镜像。等待拉取完镜像就会启动对应的Pod。

[root@k8s-node01 ~]# docker ps
CONTAINER ID        IMAGE                  COMMAND                  CREATED             STATUS              PORTS               NAMES
5502c29b43df        f0fad859c909           "/opt/bin/flanneld -…"   3 minutes ago       Up 3 minutes                            k8s_kube-flannel_kube-flannel-ds-pgpr7_kube-system_23dc27e3-a5af-11e8-84d2-000c2972dc1f_1
db1cc0a6fec4        d5c25579d0ff           "/usr/local/bin/kube…"   3 minutes ago       Up 3 minutes                            k8s_kube-proxy_kube-proxy-vxckf_kube-system_23dc0141-a5af-11e8-84d2-000c2972dc1f_0
bc54ad3399e8        k8s.gcr.io/pause:3.1   "/pause"                 9 minutes ago       Up 9 minutes                            k8s_POD_kube-proxy-vxckf_kube-system_23dc0141-a5af-11e8-84d2-000c2972dc1f_0
cbfca066b71d        k8s.gcr.io/pause:3.1   "/pause"                 10 minutes ago      Up 10 minutes                           k8s_POD_kube-flannel-ds-pgpr7_kube-system_23dc27e3-a5af-11e8-84d2-000c2972dc1f_0

[root@k8s-master ~]# kubectl get pods -n kube-system -o wide
NAME                                 READY     STATUS    RESTARTS   AGE       IP              NODE
coredns-78fcdf6894-nmcmz             1/1       Running   0          1d        10.244.0.3      k8s-master
coredns-78fcdf6894-p5pfm             1/1       Running   0          1d        10.244.0.2      k8s-master
etcd-k8s-master                      1/1       Running   1          1d        192.168.56.11   k8s-master
kube-apiserver-k8s-master            1/1       Running   8          1d        192.168.56.11   k8s-master
kube-controller-manager-k8s-master   1/1       Running   4          1d        192.168.56.11   k8s-master
kube-flannel-ds-n5c86                1/1       Running   0          1d        192.168.56.11   k8s-master
kube-flannel-ds-pgpr7                1/1       Running   1          1d        192.168.56.12   k8s-node01
kube-proxy-rxlt7                     1/1       Running   1          1d        192.168.56.11   k8s-master
kube-proxy-vxckf                     1/1       Running   0          1d        192.168.56.12   k8s-node01
kube-scheduler-k8s-master            1/1       Running   2          1d        192.168.56.11   k8s-master

[root@k8s-master ~]# kubectl get node　　#此时再查看状态已经变成Ready
NAME         STATUS    ROLES     AGE       VERSION
k8s-master   Ready     master    1d        v1.11.2
k8s-node01   Ready     <none>    1d        v1.11.2

7、新增加集群的Worker节点

[root@k8s-node02 ~]# yum install -y docker kubeadm kubelet
[root@k8s-node02 ~]# systemctl enable docker kubelet
[root@k8s-node02 ~]# systemctl start docker

同样预先拉取好node节点所需镜像，在此处犯错的还有，根据官方说明tonken的默认有效时间为24h，由于时间差，导致这里的token失效，可以使用kubeadm token list查看token，发现之前初始化的tonken已经失效了。

[root@k8s-master ~]# kubeadm token list
TOKEN                     TTL       EXPIRES                     USAGES                   DESCRIPTION   EXTRA GROUPS

dx7mko.j2ug1lqjra5bf6p2   <invalid>   2018-08-22T18:15:43-04:00   authentication,signing   The default bootstrap token generated by ‘kubeadm init‘.   system:bootstrappers:kubeadm:default-node-token

那么此处需要重新生成token，生成的方法如下：

[root@k8s-master ~]# kubeadm token create
1vxhuq.qi11t7yq2wj20cpe

如果没有值--discovery-token-ca-cert-hash，可以通过在master节点上运行以下命令链来获取：

[root@k8s-master ~]# openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null |    openssl dgst -sha256 -hex | sed ‘s/^.* //‘

8cb2de97839780a412b93877f8507ad6c94f73add17d5d7058e91741c9d5ec78

此时，再运行kube join命令将node02加入到集群当中，此处的--discovery-token-ca-cert-hash依旧可以使用初始化时的证书

[root@k8s-node02 ~]# kubeadm join 192.168.56.11:6443 --token 1vxhuq.qi11t7yq2wj20cpe --discovery-token-ca-cert-hash sha256:93fe958796db44dcc23764cb8d9b6a2e67bead072e51a3d4d3c2d36b5d1007cf

[root@k8s-master ~]# kubectl get node
NAME         STATUS    ROLES     AGE       VERSION
k8s-master   Ready     master    1d        v1.11.2
k8s-node01   Ready     <none>    1d        v1.11.2
k8s-node02   Ready     <none>    2h        v1.11.2

8、通过Taint/Toleration调整Master执行Pod策略

在前面我们了解到，默认情况下Master节点上是不允许运行用户Pod的。而Kubernetes采用的是Taint/Toleration机制。

其原理是：一旦某个节点被加上了一个Taint，即被“打上了污点”，那么所有Pod就都不能在这个节点上运行，因为Kubernetes的Pod都有"洁癖"。

除非，有个别的Pod声明自己能容忍这个"污点"，即声明Toleration，它才可以在这个节点上运行。

其中，为节点打上"污点"（Taint）的命令是：

$ kubectl taint nodes node1 foo=bar:NoSchedule

此时，该node1节点就会增加一个键值对格式的Taint，即foo=bar:NoSchedule。其中值里面的NoSchedule，意味着这个Taint只会在调度新Pod时产生作用，而不会影响已经在node1上运行的Pod，哪怕它们没有Toleration。

那么Pod又该如何声明Toleration呢？？

只需要在Pod的yaml文件中的spec部署，加入toleration字段即可：

apiVersion: v1
kind: Pod
...
spec:
  tolerations:
  - key: "foo"
    operator: "Equal"
    value: "bar"
    effect: "NoSchedule"

这个Toleration的含义是：这个Pod能容忍所有键值对为foo=bar的Taint（operator:"Equal"，"等于"操作）

我们可以通过kubectl describe来检查一下Master节点上的Taint字段：

[root@k8s-master ~]# kubectl describe node k8s-master
Name:               k8s-master
Roles:              master
.....
Taints:             node-role.kubernetes.io/master:NoSchedule
......

可以看到，Master节点默认被加上了node-role.kubernetes.io/master:NoSchedule这样的一个"污点"，其中键是node-role.kubernetes.io/master，而没有提供"值"。

此时，需要用"Exists"操作符（operator: "Exists"，"存在"即可）来说明该Pod能够容忍所有以foo为键的Taint，才能让这个Pod运行在该Master节点上：

apiVersion: v1
kind: Pod
...
spec:
  tolerations:
  - key: "foo"
    operator: "Exists"
    effect: "NoSchedule"

当然，我们还可以通过删除这个Taint，来解决污点阻碍的问题：

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

我们在"node-role.kubernetes.io/master"这个键后面增加了一个横线"-"，表示移除所有以"node-role.kubernetes.io/master"为键的Taint。

到此，使用kubeadm部署k8s集群就暂时告一段落啦！！！！

Kubernetes学习之路（一）之Kubeadm部署K8S集群

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原文地址：http://blog.51cto.com/jinlong/2311708