首页 资讯 社群 我的社区 搜索

使用kubeadm搭建Kubernetes(1.10.2)集群(国内环境)

LM123
2019-05-28 17:17:57

目标

  • 在您的机器上建立一个安全的Kubernetes集群。
  • 在集群里安装网络插件,以便应用之间可以相互通讯。
  • 在集群上运行一个简单的微服务。

准备

主机

  • 一台或多台运行Ubuntu 16.04+的主机。
  • 最好选至少有 2 GB 内存的双核主机。
  • 集群中完整的网络连接,公网或者私网都可以。

软件

安装Docker

sudo apt-get update
sudo apt-get install -y docker.io

Kubunetes建议使用老版本的docker.io,如果需要使用最新版的docker-ce,可参考上一篇博客:Docker初体验

禁用swap文件

然后需要禁用swap文件,这是Kubernetes的强制步骤。实现它很简单,编辑/etc/fstab文件,注释掉引用swap的行,保存并重启后输入sudo swapoff -a即可。

对于禁用swap内存,你可能会有点不解,具体原因可以查看Github上的Issue:Kubelet/Kubernetes should work with Swap Enabled。

步骤

(1/4)安装 kubeadm, kubelet and kubectl

  • kubeadm: 引导启动k8s集群的命令工具。
  • kubelet: 在群集中的所有计算机上运行的组件, 并用来执行如启动pods和containers等操作。
  • kubectl: 用于操作运行中的集群的命令行工具。
sudo apt-get update && sudo apt-get install -y apt-transport-https
curl -s http://packages.faasx.com/google/apt/doc/apt-key.gpg | sudo apt-key add -
sudo cat <<EOF >/etc/apt/sources.list.d/kubernetes.list
deb http://mirrors.ustc.edu.cn/kubernetes/apt/ kubernetes-xenial main
EOF
sudo apt-get update
sudo apt-get install -y kubelet kubeadm kubectl
apt-key下载地址使用了国内镜像,官方地址为:https://packages.cloud.google.com/apt/doc/apt-key.gpg。
apt安装包地址使用了中科大的镜像,官方地址为:http://apt.kubernetes.io/。

(2/4)初始化master节点

由于网络原因,我们需要提前拉取k8s初始化需要用到的Images,并添加对应的k8s.gcr.io标签:

## 拉取镜像
docker pull reg.qiniu.com/k8s/kube-apiserver-amd64:v1.10.2
docker pull reg.qiniu.com/k8s/kube-controller-manager-amd64:v1.10.2
docker pull reg.qiniu.com/k8s/kube-scheduler-amd64:v1.10.2
docker pull reg.qiniu.com/k8s/kube-proxy-amd64:v1.10.2
docker pull reg.qiniu.com/k8s/etcd-amd64:3.1.12
docker pull reg.qiniu.com/k8s/pause-amd64:3.1

## 添加Tag
docker tag reg.qiniu.com/k8s/kube-apiserver-amd64:v1.10.2 k8s.gcr.io/kube-apiserver-amd64:v1.10.2
docker tag reg.qiniu.com/k8s/kube-scheduler-amd64:v1.10.2 k8s.gcr.io/kube-scheduler-amd64:v1.10.2
docker tag reg.qiniu.com/k8s/kube-controller-manager-amd64:v1.10.2 k8s.gcr.io/kube-controller-manager-amd64:v1.10.2
docker tag reg.qiniu.com/k8s/kube-proxy-amd64:v1.10.2 k8s.gcr.io/kube-proxy-amd64:v1.10.2
docker tag reg.qiniu.com/k8s/etcd-amd64:3.1.12 k8s.gcr.io/etcd-amd64:3.1.12
docker tag reg.qiniu.com/k8s/pause-amd64:3.1 k8s.gcr.io/pause-amd64:3.1

## 在Kubernetes 1.10 中,增加了CoreDNS,如果使用CoreDNS(默认关闭),则不需要下面三个镜像。
docker pull reg.qiniu.com/k8s/k8s-dns-sidecar-amd64:1.14.10
docker pull reg.qiniu.com/k8s/k8s-dns-kube-dns-amd64:1.14.10
docker pull reg.qiniu.com/k8s/k8s-dns-dnsmasq-nanny-amd64:1.14.10

docker tag reg.qiniu.com/k8s/k8s-dns-sidecar-amd64:1.14.10 k8s.gcr.io/k8s-dns-sidecar-amd64:1.14.10
docker tag reg.qiniu.com/k8s/k8s-dns-kube-dns-amd64:1.14.10 k8s.gcr.io/k8s-dns-kube-dns-amd64:1.14.10
docker tag reg.qiniu.com/k8s/k8s-dns-dnsmasq-nanny-amd64:1.14.10 k8s.gcr.io/k8s-dns-dnsmasq-nanny-amd64:1.14.10
据说kubeadm可以自定义镜像Registry,但我并没有实验成功。

Master节点就是运行着控制组件的机器,包括etcd(集群数据库)和API服务(kubectl CLI通讯服务)。
初始化master节点, 只需随便在一台装过kubeadm的机器上运行如下命令:

sudo kubeadm init --kubernetes-version=v1.10.2 --feature-gates=CoreDNS=true --pod-network-cidr=192.168.0.0/16

init 常用主要参数:

  • --kubernetes-version: 指定Kubenetes版本,如果不指定该参数,会从google网站下载最新的版本信息。

  • --pod-network-cidr: 指定pod网络的IP地址范围,它的值取决于你在下一步选择的哪个网络网络插件,比如我在本文中使用的是Calico网络,需要指定为192.168.0.0/16

  • --apiserver-advertise-address: 指定master服务发布的Ip地址,如果不指定,则会自动检测网络接口,通常是内网IP。

  • --feature-gates=CoreDNS: 是否使用CoreDNS,值为true/false,CoreDNS插件在1.10中提升到了Beta阶段,最终会成为Kubernetes的缺省选项。

关于kubeadm更详细的的介绍请参考kubeadm官方文档

最终输出如下:

raining@raining-ubuntu:~$ sudo kubeadm init --kubernetes-version=v1.10.2 --feature-gates=CoreDNS=true --pod-network-cidr=192.168.0.0/16
[sudo] password for raining: 
[init] Using Kubernetes version: v1.10.2
[init] Using Authorization modes: [Node RBAC]
[preflight] Running pre-flight checks.
    [WARNING SystemVerification]: docker version is greater than the most recently validated version. Docker version: 17.12.1-ce. Max validated version: 17.03
    [WARNING Service-Docker]: docker service is not enabled, please run 'systemctl enable docker.service'
    [WARNING FileExisting-crictl]: crictl not found in system path
Suggestion: go get github.com/kubernetes-incubator/cri-tools/cmd/crictl
[preflight] Starting the kubelet service
[certificates] Generated ca certificate and key.
[certificates] Generated apiserver certificate and key.
[certificates] apiserver serving cert is signed for DNS names [raining-ubuntu kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.168.0.8]
[certificates] Generated apiserver-kubelet-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 [localhost] and IPs [127.0.0.1]
[certificates] Generated etcd/peer certificate and key.
[certificates] etcd/peer serving cert is signed for DNS names [raining-ubuntu] and IPs [192.168.0.8]
[certificates] Generated etcd/healthcheck-client certificate and key.
[certificates] Generated apiserver-etcd-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] 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 39.501722 seconds
[uploadconfig] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[markmaster] Will mark node raining-ubuntu as master by adding a label and a taint
[markmaster] Master raining-ubuntu tainted and labelled with key/value: node-role.kubernetes.io/master=""
[bootstraptoken] Using token: vtyk9m.g4afak37myq3rsdi
[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 192.168.0.8:6443 --token vtyk9m.g4afak37myq3rsdi --discovery-token-ca-cert-hash sha256:19246ce11ba3fc633fe0b21f2f8aaaebd7df9103ae47138dc0dd615f61a32d99

如果想在非root用户下使用kubectl,可以执行如下命令(也是kubeadm init输出的一部分):

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

kubeadm init 输出的token用于master和加入节点间的身份认证,token是机密的,需要保证它的安全,因为拥有此标记的人都可以随意向集群中添加节点。你也可以使用kubeadm命令列出,创建,删除Token,有关详细信息, 请参阅官方引用文档

我们在浏览器中输入https://<master-ip>:6443来验证一下是否部署成功,返回如下:

{
  "kind": "Status",
  "apiVersion": "v1",
  "metadata": {
    
  },
  "status": "Failure",
  "message": "forbidden: User "system:anonymous" cannot get path "/"",
  "reason": "Forbidden",
  "details": {
    
  },
  "code": 403
}

(3/4) 安装网络插件

安装一个网络插件是必须的,因为你的pods之间需要彼此通信。

网络部署必须是优先于任何应用的部署,如kube-dns(本文中使用的是coredns)在网络部署成功之前是无法使用的。kubeadm只支持容器网络接口(CNI)的网络类型(不支持kubenet)。

比较常见的network addon有:Calico, Canal, Flannel, Kube-router, Romana, Weave Net等。详细的网络列表可参考插件页面

使用下列命令来安装网络插件:

kubectl apply -f <add-on.yaml>

在本文中,我使用的是Calico网络,安装如下:

# 使用国内镜像
kubectl apply -f http://mirror.faasx.com/kubernetes/installation/hosted/kubeadm/1.7/calico.yaml

为了Calico可以正常运行,必须在执行kubeadm init时使用 --pod-network-cidr=192.168.0.0/16。

更详细的可以查看Calico官方文档:kubeadm quickstart

网络插件安装完成后,可以通过检查coredns pod的运行状态来判断网络插件是否正常运行:

kubectl get pods --all-namespaces

# 输出
NAMESPACE     NAME                                      READY     STATUS    RESTARTS   AGE
kube-system   calico-etcd-zxmvh                         1/1       Running   0          4m
kube-system   calico-kube-controllers-f9d6c4cb6-42w9j   1/1       Running   0          4m
kube-system   calico-node-jq5qb                         2/2       Running   0          4m
kube-system   coredns-7997f8864c-kfswc                  1/1       Running   0          1h
kube-system   coredns-7997f8864c-ttvj2                  1/1       Running   0          1h
kube-system   etcd-raining-ubuntu                       1/1       Running   0          1h
kube-system   kube-apiserver-raining-ubuntu             1/1       Running   0          1h
kube-system   kube-controller-manager-raining-ubuntu    1/1       Running   0          1h
kube-system   kube-proxy-vrjlq                          1/1       Running   0          1h
kube-system   kube-scheduler-raining-ubuntu             1/1       Running   0          1h

等待coredns pod的状态变成Running,就可以继续添加从节点了。

隔离主节点

默认情况下,出于安全的考虑,并不会在主节点上运行pod,如果你想在主节点上运行pod,比如:运行一个单机版的kubernetes集群时,可运行下面的命令:

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

输出类似这样:

node "test-01" untainted
taint key="dedicated" and effect="" not found.
taint key="dedicated" and effect="" not found.

这将移除所有节点的node-role.kubernetes.io/master标志,包括主节点,Scheduler便可以在任何节点上安排运行pod了。

(4/4)加入其他节点

节点就是你的负载(容器和pod等等)运行的地方,往集群里添加节点,只需要在每台机器上执行下列几步:

  • SSH 登录机器
  • 切换到root (比如 sudo su -)
  • 执行kubeadm init输出的那句命令: 
  • kubeadm join --token <token> <master-ip>:<master-port> --discovery-token-ca-cert-hash sha256:<hash>

执行后输出类似这样:

raining@ubuntu1:~$ sudo kubeadm join 192.168.0.8:6443 --token vtyk9m.g4afak37myq3rsdi --discovery-token-ca-cert-hash sha256:19246ce11ba3fc633fe0b21f2f8aaaebd7df9103ae47138dc0dd615f61a32d99
[preflight] Running pre-flight checks.
    [WARNING SystemVerification]: docker version is greater than the most recently validated version. Docker version: 17.12.1-ce. Max validated version: 17.03
    [WARNING Service-Docker]: docker service is not enabled, please run 'systemctl enable docker.service'
    [WARNING FileExisting-crictl]: crictl not found in system path
Suggestion: go get github.com/kubernetes-incubator/cri-tools/cmd/crictl
[preflight] Starting the kubelet service
[discovery] Trying to connect to API Server "192.168.0.8:6443"
[discovery] Created cluster-info discovery client, requesting info from "https://192.168.0.8:6443"
[discovery] Requesting info from "https://192.168.0.8:6443" again to validate TLS against the pinned public key
[discovery] Cluster info signature and contents are valid and TLS certificate validates against pinned roots, will use API Server "192.168.0.8:6443"
[discovery] Successfully established connection with API Server "192.168.0.8:6443"

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

Run 'kubectl get nodes' on the master to see this node join the cluster.

几秒后,你在主节点上运行kubectl get nodes就可以看到新加的机器了:

NAME             STATUS    ROLES     AGE       VERSION
raining-ubuntu   Ready     master    1h        v1.10.2
ubuntu1          Ready     <none>    2m        v1.10.2

(可选)在非主节点上管理集群

为了可以在其他电脑上使用kubectl来管理你的集群,可以从主节点上复制管理员 的kubeconfig文件到你的电脑上:

scp root@<master ip>:/etc/kubernetes/admin.conf .
kubectl --kubeconfig ./admin.conf get nodes

(可选)映射API服务到本地

如果你想从集群外部连接到API服务,可以使用工具kubectl proxy:

scp root@<master ip>:/etc/kubernetes/admin.conf .
kubectl --kubeconfig ./admin.conf proxy

这样就可以在本地这样 http://localhost:8001/api/v1 访问到API服务了。

(可选)部署一个微服务

现在可以测试你新搭建的集群了,Sock Shop就是一个微服务的样本,它体现了在Kubernetes里如何运行和连接一系列的服务。想了解更多关于微服务的内容,请查看GitHub README

kubectl create namespace sock-shop
kubectl apply -n sock-shop -f "https://github.com/microservices-demo/microservices-demo/blob/master/deploy/kubernetes/complete-demo.yaml?raw=true"

可以通过以下命令来查看前端服务是否有开放对应的端口:

kubectl -n sock-shop get svc front-end

输出类似:

NAME        TYPE       CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
front-end   NodePort   10.107.207.35   <none>        80:30001/TCP   31s

可能需要几分钟时间来下载和启用所有的容器,通过kubectl get pods -n sock-shop来获取服务的状态。

输出如下:

raining@raining-ubuntu:~$ kubectl get pods -n sock-shop
NAME                            READY     STATUS    RESTARTS   AGE
carts-6cd457d86c-wdbsg          1/1       Running   0          1m
carts-db-784446fdd6-9gsrs       1/1       Running   0          1m
catalogue-779cd58f9b-nf6n4      1/1       Running   0          1m
catalogue-db-6794f65f5d-kwc2x   1/1       Running   0          1m
front-end-679d7bcb77-4hbjq      1/1       Running   0          1m
orders-755bd9f786-gbspz         1/1       Running   0          1m
orders-db-84bb8f48d6-98wsm      1/1       Running   0          1m
payment-674658f686-xc7gk        1/1       Running   0          1m
queue-master-5f98bbd67-xgqr6    1/1       Running   0          1m
rabbitmq-86d44dd846-nf2g6       1/1       Running   0          1m
shipping-79786fb956-bs7jn       1/1       Running   0          1m
user-6995984547-nvqw4           1/1       Running   0          1m
user-db-fc7b47fb9-zcf5r         1/1       Running   0          1m

然后在你的浏览器里访问集群节点的IP和对应的端口,比如http://<master_ip>/<cluster-ip>:<port>。 在这个例子里,可能是30001,但是它可能跟你的不一样。如果有防火墙的话,确保在你访问之前开放了对应的端口。

需要注意的是,如果在多节点部署时,要使用节点的IP进行访问,而不是Master服务器的IP。

最后,卸载socks shop, 只需要在主节点上运行:

kubectl delete namespace sock-shop

卸载集群

想要撤销kubeadm做的事,首先要排除节点,并确保在关闭节点之前要清空节点。

在主节点上运行:

kubectl drain <node name> --delete-local-data --force --ignore-daemonsets
kubectl delete node <node name>

然后在需要移除的节点上,重置kubeadm的安装状态:

kubeadm reset

如果你想重新配置集群,只需运行kubeadm init或者kubeadm join并使用所需的参数即可。

参考资料

用户评论