kubeadm部署单master Kuberntes集群

本文参考kubernetes docs 使用kubeadm创建single master的Kuberntes集群

虚机两台Centos75
Kubernetes Yum Repo采用国内阿里源
版本 v1.14.1 （该版本发布时间2019-04-09）
Pod网络采用Calico

1 配置镜像源

以yum为例，Ubuntu可以采用中科大ustc的源

官方Google源

cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes
baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg
exclude=kube*
EOF

国内阿里源

cat <<EOF > /etc/yum.repos.d/kubernetes.repo
[kubernetes]
name=Kubernetes baseurl=http://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
repo_gpgcheck=0
gpgkey=http://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg http://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg
EOF

2 初始化主机

# 2.1 设置 selinux, 可以直接disable，也可以设置为permissive
## 我一般会关掉firewalld
setenforce 0
sed -i 's/^SELINUX=enforcing$/SELINUX=permissive/' /etc/selinux/config
# 2.2 关闭swap，不关闭的话 需要设置kubelet的参数 --fail-swap-on=false （默认为true）
swapoff -a
## 查看swap
free -m
## 编辑 /etc/fstab 取消开机加载swap

# 2.3 设置网络
## 2.3.1 加载内核模块 （可以直接进行2.3.3）
modprobe br_netfilter
lsmod | grep br_netfilter
## 2.3.2 配置网络等系统参数
cat <<EOF >  /etc/sysctl.d/k8s.conf
vm.swappiness = 0
net.ipv4.ip_forward = 1
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF
sysctl --system

## 2.3.3 配置内核启动自动加载
将需要加载的内核写入 /etc/modules-load.d 目录下某个文件中，注意文件权限

## 2.3.4 安装ipvs, 取代 iptables
yum -y install ipvsadm
cat > /etc/modules-load.d/ipvs  << EOF
br_netfilter
ip_vs_rr
ip_vs_wrr
ip_vs_sh
ip_vs
EOF
for m in `cat /etc/modules-load.d/ipvs`; do echo $m; done

3 下载kubernetes文件

# 查看当前yum提供的kubeadm版本，选择需要安装的版本
yum search --showduplicates kubeadmin 
# 直接安装最新版
yum install -y kubelet kubeadm kubectl --disableexcludes=kubernetes
# 如果用docker，kubelet会自动探测docker使用的cgroup driver，一般是cgroupfs，安装docker如下
docker version
yum install -y docker --disableexcludes=docker-ce
> 阿里有docker源，配置如下
> curl -O /etc/yum.repos.d/docker-ce.repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
# 如果使用其他cri 需要修改kubelet参数文件设置合适的cgroup driver
> KUBELET_EXTRA_ARGS=--cgroup-driver=whatyouwant

# 配置开机启动
systemctl enable --now kubelet (--now 同时启动kubelet)
> 此时 systemctl status kubelet 会得到kubelet无法启动，因为 /var/lib/kubelet/config.yaml 文件不存在
> 可以暂时不处理, 后面 kubeadm init 命令会创建该文件

4 master 节点

kubeadm  init --pod-network-cidr=192.169.0.0/16 --image-repository registry.aliyuncs.com/google_containers
> --pod-network-cidr 注意不要和现有主机上的各网卡的网络冲突
> --kubernetes-version v1.14.1  可用该参数制定版本,需要比刚才下载的kubelet的版本低，这样才能兼容
> --apiserver-advertise-address= 指定服务监听ip

从该命令的输出, 可以看到创建了数字证书，设置/var/lib/kubelet/config.yaml 等配置文件各关键步骤

同时：

• 1 提示需要安装pod network
• 2 设置kubectl命令的配置文件的方法
• 3 添加其他节点所使用的命令及参数

输出如下：

I0501 19:53:16.073098   11685 version.go:96] could not fetch a Kubernetes version from the internet: unable to get URL "https://dl.k8s.io/release/stable-1.txt": Get https://dl.k8s.io/release/stable-1.txt: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)
I0501 19:53:16.073210   11685 version.go:97] falling back to the local client version: v1.14.1
[init] Using Kubernetes version: v1.14.1
[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 "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [c75a.shared localhost] and IPs [10.211.55.7 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [c75a.shared localhost] and IPs [10.211.55.7 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "apiserver-etcd-client" certificate and key
[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 [c75a.shared kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 10.211.55.7]
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-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 17.003746 seconds
[upload-config] storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.14" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --experimental-upload-certs
[mark-control-plane] Marking the node c75a.shared as control-plane by adding the label "node-role.kubernetes.io/master=''"
[mark-control-plane] Marking the node c75a.shared as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: uurhat.duj8060jmku42htb
[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 10.211.55.7:6443 --token uurhat.duj8060jmku42htb 
    --discovery-token-ca-cert-hash sha256:2a3487a02927c7c496a7516af076ac3ad16e6b3721ee6c6a025bb87beace89e2

完成此步后，我们可以用 kubectl get nodes查看当前集群的节点信息, 以及 kubectl describe node 查看 node 的 label信息，可以发现master节点被打上了node-role.kubernetes.io/master label

5 pod network

以calico为例，calico自身也可以单独安装在主机上，而非Kuberntes集群上
kubectl apply -f https://docs.projectcalico.org/v3.3/getting-started/kubernetes/installation/hosted/rbac-kdd.yaml
kubectl apply -f https://docs.projectcalico.org/v3.3/getting-started/kubernetes/installation/hosted/kubernetes-datastore/calico-networking/1.7/calico.yaml

如果kubeadm init时采用的--pod-network-cidr不是192.168.0.0/16 则需要先下载calico.yaml 修改为正确的配置

查看calico pods kubectl get pods --all-namespaces

6 添加node节点

root用户执行上面kubeadm init输出的命令, 即：
kubeadmin join apiserver_ip:apiserver_port --token token --discovery-token-ca-cert-hash sha256:<hash>

1. 如果apiserver_ip是ipv6，则采用如下格式配置ip和端口: [fd00::101]:6443

2. 如果token过期或忘记，可用命令查看或创建 kubeadm token list or kubeadm token create

3. 如果忘记证书hash，可用如下命令：

 openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa - pubin -outform der 2>/dev/null | 
  openssl dgst -sha256 -hex | sed 's/^.* //'

命令如下：

kubeadm join 10.211.55.7:6443 --token uurhat.duj8060jmku42htb 
    --discovery-token-ca-cert-hash sha256:2a3487a02927c7c496a7516af076ac3ad16e6b3721ee6c6a025bb87beace89e2

输出如下：

root@c75b ~# kubeadm join 10.211.55.7:6443 --token uurhat.duj8060jmku42htb                                                   130
     --discovery-token-ca-cert-hash sha256:2a3487a02927c7c496a7516af076ac3ad16e6b3721ee6c6a025bb87beace89e2
[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-1.14" 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.

然后在前面的master节点上执行kubectl get nodes, 新节点需要1分钟左右注册到master集群，时间取决于网络和主机性能

7 删除节点

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

为便于下次再次添加该节点需要执行：kubeadm reset
网络需要单独清理，清理之前可以先查看是否有除k8s以外的网络
iptables

iptables -F && iptables -t nat -F && iptables -t mangle -F && iptables -X

ipvs

ipvsadm -C

8 部署Dashbord Add-on

8.1 执行命令

kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/v1.10.1/src/deploy/recommended/kubernetes-dashboard.yaml

8.2 这个需要翻墙下载容器镜像 k8s.gcr.io/kubernetes-dashboard-amd64:v1.10.1

通过该文(引用3)办法，已下载镜像，可以直接使用

docker pull registry.cn-hangzhou.aliyuncs.com/xw9/kubernetes-dashboard-amd64:v1.10.1
docker tag registry.cn-hangzhou.aliyuncs.com/xw9/kubernetes-dashboard-amd64:v1.10.1 k8s.gcr.io/kubernetes-dashboard-amd64:v1.10.1

8.3 配置集群外访问
通过kubectl get svc -n kube-system 可以看到kubernetes-dashboard服务了

curl -vk https://10.110.167.233 可以看到访问成功

为了集群外访问，配置该服务为NodePort类型，也可以用Ingress等方式

kubectl edit svc kubernetes-dashboard -n kube-system
# 将spec中的type由ClusterIP改为NodePort
kubectl get svc -n kube-system # 查看使用的端口号，使用https协议即可访问

打开界面，可以看到需要上传kubeconfig文件或输入令牌

8.4 创建一个管理员用户（也可以将kubernetes-dashboard加入到cluster-admin角色中）

cat > admin-user.yaml << EOF
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: admin-user
  namespace: kube-system
  
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: admin-user
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
- kind: ServiceAccount
  name: admin-user
  namespace: kube-system
EOF

kubectl apply -f admin-user.yaml

# 获取令牌
kubectl describe secrets `kubectl get sa admin-user -o 'jsonpath={.secrets[0].name}' -n kube-system` -n kube-system | awk '$1=="token:"{print $2}'

10 运行Nginx

kubectl run nginx --image=nginx:1.16.0

11 备注

IPVS已在GA了，但安装完发现，仍然使用的是iptables，还需显式指定才能生效
kubeadm init --feature-gates=SupportIPVSProxyMode=true
待下次测试

Ref 本文参考致谢

1 kubernetes
2 zzphper blog 使用kubeadm快速部署kubernetes
3 k8s镜像推送国内
4 dashbord access
5 kubernetes dashboard user

本文为©xiaowei原创，基于CC BY-NC-SA 4.0协议公开许可, 2019-05-01

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