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kubeadm.md

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kubeadm 部署 kubernetes

安装 kubelet kubeadm kubectl

手动下载二进制文件放入 PATH，或者使用包管理工具安装。下面介绍如何使用包管理工具安装

Ubuntu/Debian

$ apt-get update && apt-get install -y apt-transport-https
$ curl https://mirrors.aliyun.com/kubernetes/apt/doc/apt-key.gpg | apt-key add -

$ cat <<EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list
deb https://mirrors.aliyun.com/kubernetes/apt/ kubernetes-xenial main
EOF

$ apt-get update
$ apt-get install -y kubelet kubeadm kubectl

CentOS/Fedora

$ cat <<EOF | sudo tee /etc/yum.repos.d/kubernetes.repo
[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

$ setenforce 0
$ sudo yum install -y kubelet kubeadm kubectl

修改内核的运行参数

$ sysctl -a | grep net.*iptables

net.bridge.bridge-nf-call-iptables = 1
# 若未输出以上结果，请执行以下命令，若正常输出，请跳过以下命令

$ cat <<EOF | sudo tee /etc/sysctl.d/99-kubernetes-cri.conf
net.bridge.bridge-nf-call-iptables  = 1
net.ipv4.ip_forward                 = 1
net.bridge.bridge-nf-call-ip6tables = 1
EOF

# 应用配置
$ sysctl --system

配置 kubelet

修改 kubelet.service (使用包管理工具安装 kubeadm 请跳过此步，查看下一步骤)

$ sudo mkdir -p /etc/systemd/system/kubelet.service.d

/etc/systemd/system/kubelet.service.d/10-kubeadm.conf 写入以下内容(内容来自包管理工具安装的 kubeadm)

# 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/sysconfig/kubelet
ExecStart=
ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS

/etc/systemd/system/kubelet.service.d/10-proxy-ipvs.conf 写入以下内容

# 启用 ipvs 相关内核模块，用于 kube-proxy
[Service]
ExecStartPre=-modprobe ip_vs
ExecStartPre=-modprobe ip_vs_rr
ExecStartPre=-modprobe ip_vs_wrr
ExecStartPre=-modprobe ip_vs_sh

/etc/systemd/system/kubelet.service 写入以下内容

[Unit]
Description=kubelet: The Kubernetes Node Agent
Documentation=https://kubernetes.io/docs/home/

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

[Install]
WantedBy=multi-user.target
# 应用配置

$ sudo systemctl daemon-reload

修改 kubelet.service (使用包管理工具安装 kubeadm)

/etc/systemd/system/kubelet.service.d/10-proxy-ipvs.conf 写入以下内容

# 启用 ipvs 相关内核模块，用于 kube-proxy
[Service]
ExecStartPre=-modprobe ip_vs
ExecStartPre=-modprobe ip_vs_rr
ExecStartPre=-modprobe ip_vs_wrr
ExecStartPre=-modprobe ip_vs_sh
# 应用配置

$ sudo systemctl daemon-reload

部署

master

$ sudo kubeadm init --image-repository registry.cn-hangzhou.aliyuncs.com/google_containers \
      --pod-network-cidr 10.244.0.0/16 \
      --v 5 \
      --ignore-preflight-errors=all
  • --pod-network-cidr 10.244.0.0/16 参数与后续 CNI 插件有关，这里以 calico 为例，若后续部署其他类型的网络插件请更改此参数。
  • 使用 配置文件 的方式这里不再赘述

执行可能出现错误，例如缺少依赖包，根据提示安装即可。

执行成功会输出

...
[addons] Applied essential addon: CoreDNS
I1116 12:35:13.270407   86677 request.go:538] Throttling request took 181.409184ms, request: POST:https://192.168.199.100:6443/api/v1/namespaces/kube-system/serviceaccounts
I1116 12:35:13.470292   86677 request.go:538] Throttling request took 186.088112ms, request: POST:https://192.168.199.100:6443/api/v1/namespaces/kube-system/configmaps
[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 192.168.199.100:6443 --token cz81zt.orsy9gm9v649e5lf \
    --discovery-token-ca-cert-hash sha256:5edb316fd0d8ea2792cba15cdf1c899a366f147aa03cba52d4e5c5884ad836fe

node 工作节点

在 另一主机 重复 部署 小节以前的步骤，安装配置好 kubelet。根据提示，加入到集群。

$ kubeadm join 192.168.199.100:6443 --token cz81zt.orsy9gm9v649e5lf \
    --discovery-token-ca-cert-hash sha256:5edb316fd0d8ea2792cba15cdf1c899a366f147aa03cba52d4e5c5884ad836fe

使用

将 /etc/kubernetes/admin.conf 复制到 ~/.kube/config

执行 $ kubectl get all -A

由于未部署 CNI 插件，CoreDNS 未正常启动。

部署 CNI -- calico

修改 addons/cni/calico/configMap.yaml 中的 192.168.0.0/16 为 10.244.0.0/16(同 flannel 一致)

有 三种方式 存储 calico 数据,这里采用第一种 Installing with the Kubernetes API datastore—50 nodes or less

修改内核参数

/etc/sysctl.d/99-kubernetes-calico.conf 写入以下内容

net.ipv4.conf.all.rp_filter = 1

Fedora 31 默认值为 2 ,其他系统通过 sysctl -a | grep net.ipv4.conf.all.rp_filter 查看

# 应用配置

$ sysctl --system

不进行以上步骤的话,会报如下错误

2019-11-17 03:23:02.084 [FATAL][5336] int_dataplane.go 1032: Kernel's RPF check is set to 'loose'.  This would allow endpoints to spoof their IP address.  Calico requires net.ipv4.conf.all.rp_filter to be set to 0 or 1. If you require loose RPF and you are not concerned about spoofing, this check can be disabled by setting the IgnoreLooseRPF configuration parameter to 'true'.

部署

$ kubectl apply -k addons/cni/calico

kube-proxy

启用 ipvs 模式

$ kubectl edit cm kube-proxy -n kube-system
- mode: ""
+ mode: "ipvs"

加载内核模块(手动加载，实际上已通过 systemd 的配置执行了加载命令，这里介绍一下原理)

# 根据 kube-proxy 日志，查看未加载模块
$ E1116 12:53:34.421604       1 server_others.go:339] can't determine whether to use ipvs proxy, error: IPVS proxier will not be used because the following required kernel modules are not loaded: [ip_vs_rr ip_vs_wrr ip_vs_sh]

$ modprobe -- ip_vs
$ modprobe -- ip_vs_rr
$ modprobe -- ip_vs_wrr
$ modprobe -- ip_vs_sh

$ modprobe -- nf_conntrack_ipv4
# linux 内核 4.19+
$ modprobe -- nf_conntrack

开机自动加载内核模块(Ubuntu)

$ cat <<EOF | sudo tee /etc/modules
ip_vs
ip_vs_rr
ip_vs_wrr
ip_vs_sh
EOF

CentOS 系列请参考 https://blog.csdn.net/s1234567_89/article/details/51836344

重启 kube-proxy (注意将 XXX 替换为自己的名称)

$ kubectl get pod -n kube-system

$ kubectl get pod/kube-proxy-XXX -n kube-system -o yaml | kubectl replace --force -f -

master 节点默认不能运行 pod

也就是说如果用 kubeadm 部署一个单节点集群不能使用,请执行以下命令

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

# 恢复默认值
# $ kubectl taint nodes NODE_NAME node-role.kubernetes.io/master=true:NoSchedule

高可用

$ sudo kubeadm init --apiserver-cert-extra-sans=xxx.com --control-plane-endpoint=xxx.com:6443 其他参数

$ sudo kubeadm join --control-plane 其他参数
  • 高可用，入口地址不能为 IP(127.0.0.1 NGINX 轮询除外，这里不做介绍) 必须为一个域名,init 时必须指定 --apiserver-cert-extra-sans=xxx.com --control-plane-endpoint=xxx.com:6443。通过 DNS 轮询 xxx.com 实现高可用(请自行搭建 DNS 服务器，这里不做介绍)

附录

使用包管理工具安装的 kubeadm 增加了哪些文件

$ yum install yum-utils -y
$ yumdownloader kubeadm
$ rpm2cpio xxx.rpm | cpio -div

新增了 /usr/lib/systemd/system/kubelet.service.d/10-kubeadm.conf 文件

# /usr/lib/systemd/system/kubelet.service.d/10-kubeadm.conf
# 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/sysconfig/kubelet
ExecStart=
ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS

kubeadm 配置文件

# 生成默认的配置文件

$ kubeadm config print init-defaults
# 使用

$ kubeadm init/join --config 配置文件名 其他参数

所需镜像

$ kubeadm config images list

使用其他运行时

~/lnmp/kubernetes/kubeadm

笔者总结

  • 关键在于配置好 kubelet
  • k8s 组件除了 kubelet 其他组件都能够以 pod 方式运行，秘诀在于使用了 hostnetwork
  • 国内网络问题（拉取不到 registry.k8s.io 镜像）：加上参数 --image-repository registry.cn-hangzhou.aliyuncs.com/google_containers 解决
  • kubelet 的参数 --cgroup-driver=systemd 一定要与 Docker(或其他的 CRI) 的一致，其他文档有介绍，这里不再赘述