使用kubeadm部署生产环境kubernetes集群

本文为基于kubeadm搭建生产环境级别高可用的k8s集群。

1. 环境准备

1.0. master硬件配置

参考:

Kubernetes集群Master节点上运行着etcd、kube-apiserver、kube-controller等核心组件,对于Kubernetes集群的稳定性有着至关重要的影响,对于生产环境的集群,必须慎重选择Master规格。Master规格跟集群规模有关,集群规模越大,所需要的Master规格也越高。

说明 :可从多个角度衡量集群规模,例如节点数量、Pod数量、部署频率、访问量。这里简单的认为集群规模就是集群里的节点数量。

对于常见的集群规模,可以参见如下的方式选择Master节点的规格(对于测试环境,规格可以小一些。下面的选择能尽量保证Master负载维持在一个较低的水平上)。

节点规模 Master规格 磁盘
1~5个节点 4核8 GB(不建议2核4 GB)
6~20个节点 4核16 GB
21~100个节点 8核32 GB
100~200个节点 16核64 GB
1000个节点 32核128GB 1T SSD

注意事项:

  • 由于Etcd的性能瓶颈,Etcd的数据存储盘尽量选择SSD磁盘。

  • 为了实现多机房容灾,可将三台master分布在一个可用区下三个不同机房。(机房之间的网络延迟在10毫秒及以下级别)

  • 申请LB来做master节点的负载均衡实现高可用,LB作为apiserver的访问地址。

1.1. 设置防火墙端口策略

生产环境设置k8s节点的iptables端口访问规则。

1.1.1. master节点端口配置

协议 方向 端口范围 目的 使用者
TCP 入站 6443 Kubernetes API server 所有
TCP 入站 2379-2380 etcd server client API kube-apiserver, etcd
TCP 入站 10250 Kubelet API 自身, 控制面
TCP 入站 10259 kube-scheduler 自身
TCP 入站 10257 kube-controller-manager 自身

1.1.2. worker节点端口配置

协议 方向 端口范围 目的 使用者
TCP 入站 10250 Kubelet API 自身, 控制面
TCP 入站 30000-32767 NodePort Services 所有

添加防火墙iptables规则

master节点开放6443、2379、2380端口。

iptables -A INPUT -p tcp -m multiport --dports 6443,2379,2380,10250 -j ACCEPT

1.2. 关闭​​swap​​分区

[root@master ~]#swapoff -a
[root@master ~]#
[root@master ~]# free -m
              total        used        free      shared  buff/cache   available
Mem:            976         366         135           6         474         393
Swap:             0           0           0

# swap 一栏为0,表示已经关闭了swap

1.3. 开启br_netfilter和bridge-nf-call-iptables

参考:https://imroc.cc/post/202105/why-enable-bridge-nf-call-iptables/

# 设置加载br_netfilter模块
cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf
overlay
br_netfilter
EOF

sudo modprobe overlay
sudo modprobe br_netfilter

# 开启bridge-nf-call-iptables ,设置所需的 sysctl 参数,参数在重新启动后保持不变
cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-iptables  = 1
net.bridge.bridge-nf-call-ip6tables = 1
net.ipv4.ip_forward                 = 1
EOF

# 应用 sysctl 参数而不重新启动
sudo sysctl --system

2. 安装容器运行时

在所有主机上安装容器运行时,推荐使用containerd为runtime。以下分别是containerd与docker的安装命令。

2.1. Containerd

1、参考:安装containerd

# for ubuntu
apt install -y containerd.io

2、生成默认配置

containerd config default > /etc/containerd/config.toml

3、修改CgroupDriver为systemd

k8s官方推荐使用systemd类型的CgroupDriver。

[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc]
  ...
  [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc.options]
    SystemdCgroup = true

4、重启containerd

systemctl restart containerd

2.2. Docker

# for ubuntu
apt install -y docker.io

官方建议配置cgroupdriver为systemd。

# 修改docker进程管理器
vi /etc/docker/daemon.json
{
"exec-opts": ["native.cgroupdriver=systemd"]
}
systemctl daemon-reload && systemctl restart docker
docker info | grep -i cgroup

2.3. Container Socket

运行时 Unix 域套接字
Containerd unix:///var/run/containerd/containerd.sock
CRI-O unix:///var/run/crio/crio.sock
Docker Engine (使用 cri-dockerd) unix:///var/run/cri-dockerd.sock

3. 安装kubeadm,kubelet,kubectl

安装脚本可参考仓库:https://github.com/huweihuang/kubeadm-scripts.git

在所有主机上安装kubeadm,kubelet,kubectl。最好版本与需要安装的k8s的版本一致。

# 以Ubuntu系统为例

# 安装仓库依赖
sudo apt-get update
sudo apt-get install -y apt-transport-https ca-certificates curl

# use google registry
sudo curl -fsSLo /usr/share/keyrings/kubernetes-archive-keyring.gpg https://packages.cloud.google.com/apt/doc/apt-key.gpg
echo "deb [signed-by=/usr/share/keyrings/kubernetes-archive-keyring.gpg] https://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list

# or use aliyun registry
curl -s https://mirrors.aliyun.com/kubernetes/apt/doc/apt-key.gpg | sudo apt-key add -
tee /etc/apt/sources.list.d/kubernetes.list <<EOF 
deb https://mirrors.aliyun.com/kubernetes/apt/ kubernetes-xenial main
EOF

# 安装指定版本的kubeadm, kubelet, kubectl
apt-get update
apt-get install -y kubelet=1.24.2-00 kubeadm=1.24.2-00 kubectl=1.24.2-00

# 查询有哪些版本
apt-cache madison kubeadm

离线下载安装

#!/bin/bash
Version=${Version:-1.24.2}
wget https://dl.k8s.io/release/v${Version}/bin/linux/amd64/kubeadm
wget https://dl.k8s.io/release/v${Version}/bin/linux/amd64/kubelet
wget https://dl.k8s.io/release/v${Version}/bin/linux/amd64/kubectl
chmod +x kubeadm kubelet kubectl
cp kubeadm kubelet kubectl /usr/bin/

# add kubelet serivce
cat > /lib/systemd/system/kubelet.service << EOF
[Unit]
Description=kubelet: The Kubernetes Node Agent
Documentation=https://kubernetes.io/docs/home/
Wants=network-online.target
After=network-online.target

[Service]
ExecStart=/usr/bin/kubelet
Restart=always
StartLimitInterval=0
RestartSec=10

[Install]
WantedBy=multi-user.target
EOF

mkdir -p /etc/systemd/system/kubelet.service.d
cat > /etc/systemd/system/kubelet.service.d/10-kubeadm.conf << \EOF
# Note: This dropin only works with kubeadm and kubelet v1.11+
[Service]
Environment="KUBELET_KUBECONFIG_ARGS=--bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf"
Environment="KUBELET_CONFIG_ARGS=--config=/var/lib/kubelet/config.yaml"
# This is a file that "kubeadm init" and "kubeadm join" generates at runtime, populating the KUBELET_KUBEADM_ARGS variable dynamically
EnvironmentFile=-/var/lib/kubelet/kubeadm-flags.env
# This is a file that the user can use for overrides of the kubelet args as a last resort. Preferably, the user should use
# the .NodeRegistration.KubeletExtraArgs object in the configuration files instead. KUBELET_EXTRA_ARGS should be sourced from this file.
EnvironmentFile=-/etc/default/kubelet
ExecStart=
ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS
EOF


systemctl daemon-reload
systemctl enable kubelet
systemctl restart kubelet

4. 配置kubeadm config

参考:

4.1. 配置项说明

4.1.1. 配置类型

kubeadm config支持以下几类配置。

apiVersion: kubeadm.k8s.io/v1beta3
kind: InitConfiguration

apiVersion: kubeadm.k8s.io/v1beta3
kind: ClusterConfiguration

apiVersion: kubelet.config.k8s.io/v1beta1
kind: KubeletConfiguration

apiVersion: kubeproxy.config.k8s.io/v1alpha1
kind: KubeProxyConfiguration

apiVersion: kubeadm.k8s.io/v1beta3
kind: JoinConfiguration

可以使用以下命令打印init和join的默认配置。

kubeadm config print init-defaults
kubeadm config print join-defaults

4.1.2. Init配置

kubeadm init配置中只有InitConfigurationClusterConfiguration 是必须的。

InitConfiguration:

apiVersion: kubeadm.k8s.io/v1beta3
kind: InitConfiguration
bootstrapTokens:
  ...
nodeRegistration:
  ...
  • bootstrapTokens
  • nodeRegistration
    • criSocket:runtime的socket
    • name:节点名称
  • localAPIEndpoint
    • advertiseAddress:apiserver的广播IP
    • bindPort:k8s控制面安全端口

ClusterConfiguration:

apiVersion: kubeadm.k8s.io/v1beta3
kind: ClusterConfiguration
networking:
  ...
etcd:
  ...
apiServer:
  extraArgs:
    ...
  extraVolumes:
    ...
...
  • networking:

    • podSubnet:Pod CIDR范围
    • serviceSubnet: service CIDR范围
    • dnsDomain
  • etcd:

    • dataDir:Etcd的数据存储目录
  • apiserver

    • certSANs:设置额外的apiserver的域名签名证书
  • imageRepository:镜像仓库

  • controlPlaneEndpoint:控制面LB的域名

  • kubernetesVersion:k8s版本

4.2. Init配置示例

在master节点生成默认配置,并修改配置参数。

kubeadm config print init-defaults > kubeadm-config.yaml

修改配置内容

apiVersion: kubeadm.k8s.io/v1beta3
bootstrapTokens:
- groups:
  - system:bootstrappers:kubeadm:default-node-token
  token: abcdef.0123456789abcdef
  ttl: 24h0m0s
  usages:
  - signing
  - authentication
kind: InitConfiguration
localAPIEndpoint:
  advertiseAddress: 1.2.3.4 # 修改为apiserver的IP 或者去掉localAPIEndpoint则会读取默认IP。
  bindPort: 6443
nodeRegistration:
  criSocket: unix:///var/run/containerd/containerd.sock
  imagePullPolicy: IfNotPresent
  name: node
  taints: null
---
apiServer:
  certSANs:
  - lb.k8s.domain  # 添加额外的apiserver的域名
  - <vip/lb_ip>
  timeoutForControlPlane: 4m0s
apiVersion: kubeadm.k8s.io/v1beta3
certificatesDir: /etc/kubernetes/pki
clusterName: kubernetes
controllerManager: {}
dns: {}   # 默认为coredns
etcd:
  local:
    dataDir: /data/etcd   # 修改etcd的存储盘目录
imageRepository: k8s.gcr.io  # 修改镜像仓库地址
controlPlaneEndpoint: lb.k8s.domain  # 修改控制面域名
kind: ClusterConfiguration
kubernetesVersion: 1.24.0  # k8s 版本
networking:
  dnsDomain: cluster.local
  serviceSubnet: 10.96.0.0/12
  podSubnet: 10.244.0.0/16  # 设置pod的IP范围
scheduler: {}
---
kind: KubeletConfiguration
apiVersion: kubelet.config.k8s.io/v1beta1
cgroupDriver: systemd   # 设置为systemd

安装完成后可以查看kubeadm config

kubectl get cm -n kube-system kubeadm-config -oyaml

5. 安装Master控制面

提前拉取镜像:

kubeadm config images pull

5.1. 安装master

sudo kubeadm init --config kubeadm-config.yaml --upload-certs  --node-name <nodename>

部署参数说明:

  • --control-plane-endpoint:指定控制面(kube-apiserver)的IP或DNS域名地址。

  • --apiserver-advertise-address:kube-apiserver的IP地址。

  • --pod-network-cidr:pod network范围,控制面会自动给每个节点分配CIDR。

  • --service-cidr:service的IP范围,default "10.96.0.0/12"。

  • --kubernetes-version:指定k8s的版本。

  • --image-repository:指定k8s镜像仓库地址。

  • --upload-certs :标志用来将在所有控制平面实例之间的共享证书上传到集群。

  • --node-name:hostname-override,作为节点名称。

执行完毕会输出添加master和添加worker的命令如下:

...
You can now join any number of control-plane node by running the following command on each as a root:
    kubeadm join 192.168.0.200:6443 --token 9vr73a.a8uxyaju799qwdjv --discovery-token-ca-cert-hash sha256:7c2e69131a36ae2a042a339b33381c6d0d43887e2de83720eff5359e26aec866 --control-plane --certificate-key f8902e114ef118304e561c3ecd4d0b543adc226b7a07f675f56564185ffe0c07

Please note that the certificate-key gives access to cluster sensitive data, keep it secret!
As a safeguard, uploaded-certs will be deleted in two hours; If necessary, you can use kubeadm init phase upload-certs to reload certs afterward.

Then you can join any number of worker nodes by running the following on each as root:
    kubeadm join 192.168.0.200:6443 --token 9vr73a.a8uxyaju799qwdjv --discovery-token-ca-cert-hash sha256:7c2e69131a36ae2a042a339b33381c6d0d43887e2de83720eff5359e26aec866

5.2. 添加其他master

添加master和添加worker的差别在于添加master多了--control-plane 参数来表示添加类型为master

kubeadm join <control-plane-endpoint>:6443 --token <token> \
--discovery-token-ca-cert-hash sha256:<hash> \
--control-plane --certificate-key <certificate-key> \
--node-name <nodename>

6. 添加Node节点

kubeadm join <control-plane-endpoint>:6443 --token <token> \
--discovery-token-ca-cert-hash sha256:<hash> \
--cri-socket /run/containerd/containerd.sock \
--node-name <nodename>

7. 安装网络插件

## 如果安装之后node的状态都改为ready,即为成功
wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
kubectl apply -f ./kube-flannel.yml
kubectl get nodes

如果Pod CIDR的网段不是10.244.0.0/16,则需要加flannel配置中的网段更改为与Pod CIDR的网段一致。

7.1. 问题

  Warning  FailedCreatePodSandBox  4m6s                kubelet            Failed to create pod sandbox: rpc error: code = Unknown desc = failed to setup network for sandbox "300d9b570cc1e23b6335c407b8e7d0ef2c74dc2fe5d7a110678c2dc919c62edf": plugin type="flannel" failed (add): failed to delegate add: failed to set bridge addr: "cni0" already has an IP address different from 10.244.3.1/24

原因:

宿主机节点有cni0网卡,且网卡的IP段与flannel的CIDR网段不同,因此需要删除该网卡,让其重建。

查看cni0网卡

# ifconfig cni0 |grep -w inet
        inet 10.244.5.1  netmask 255.255.255.0  broadcast 10.244.116.255

查看flannel配置

# cat /run/flannel/subnet.env
FLANNEL_NETWORK=10.244.0.0/16
FLANNEL_SUBNET=10.244.116.1/24
FLANNEL_MTU=1450
FLANNEL_IPMASQ=true

发现cni0 IP与FLANNEL_SUBNET网段不一致,因此删除cni0重建。

解决:

ifconfig cni0 down    
ip link delete cni0

8. 部署dashboard

kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/v2.5.0/aio/deploy/recommended.yaml

镜像: kubernetesui/dashboard:v2.5.0

默认端口:8443

登录页面需要填入token或kubeconfig

参考:dashboard/creating-sample-user

apiVersion: v1
kind: ServiceAccount
metadata:
  name: admin-user
  namespace: kubernetes-dashboard
---
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: kubernetes-dashboard

创建用户

kubectl -n kubernetes-dashboard create token admin-user

9. 重置部署

# kubeadm重置
kubeadm reset

# 清空数据目录
rm -fr /data/etcd
rm -fr /etc/kubernetes
rm -fr ~/.kube/

删除flannel

ifconfig cni0 down
ip link delete cni0
ifconfig flannel.1 down
ip link delete flannel.1
rm -rf /var/lib/cni/
rm -f /etc/cni/net.d/*

10. 问题排查

10.1. kubeadm token过期

问题描述:

添加节点时报以下错误:

[discovery] The cluster-info ConfigMap does not yet contain a JWS signature for token ID "abcdef", will try again

原因:token过期,初始化token后会在24小时候会被master删除。

解决办法:

# 重新生成token
kubeadm token create --print-join-command
kubeadm token list

# kubeadm token create
oumnnc.aqlxuvdbntlvzoiv

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

基于新生成的token重新添加节点。

10.2. 修改kubeadm join的master IP或端口

kubeadm join命令会去kube-public命名空间获取名为cluster-infoConfigMap。如果需要修改kubeadm join使用的master的IP或端口,则需要修改cluster-info的configmap。

# 查看cluster-info
kubectl -n kube-public get configmaps cluster-info -o yaml

# 修改cluster-info
kubectl -n kube-public edit configmaps cluster-info

修改配置文件中的server字段

clusters:
- cluster:
    certificate-authority-data: xxx
    server: https://lb.k8s.domain:36443
  name: ""

执行kubeadm join的命令时指定新修改的master地址。

10.3. conntrack not found

[preflight] Some fatal errors occurred:
    [ERROR FileExisting-conntrack]: conntrack not found in system path

解决方法:

apt -y install conntrack

10.4. Kubelet: unable to determine runtime API version

Error: failed to run Kubelet: unable to determine runtime API version: rpc error:code = Unavailable desc = connection error: desc = "transport: Error while dialing dial unix: missing address" 

解决方法:

检查kubelet的启动参数,可以用二进制直接添加参数debug

# 查看启动参数是否遗漏,比如10-kubeadm.conf 文件参数缺失
systemctl cat --no-pager kubelet

cat /lib/systemd/system/kubelet.service

cat /etc/systemd/system/kubelet.service.d/10-kubeadm.conf

参考:


最后修改 April 2, 2024: update k8s and linux (9e9bef5)