跳到主要内容

Kubernetes 集群部署

现在我们使用 kubeadm 从头搭建一个使用 containerd 作为容器运行时的 Kubernetes 集群,这里我们安装最新的 v1.22.2 版本。

环境准备

3 个节点,都是 Centos 7.6 系统,内核版本:3.10.0-1062.4.1.el7.x86_64,在每个节点上添加 hosts 信息:

➜  ~ cat /etc/hosts
192.168.31.31 master1
192.168.31.108 node1
192.168.31.46 node2
hostname

节点的 hostname 必须使用标准的 DNS 命名,另外千万不用什么默认的localhost 的 hostname,会导致各种错误出现的。在 Kubernetes 项目里,机器的名字以及一切存储在 Etcd 中的 API 对象,都必须使用标准的 DNS 命名(RFC 1123)。可以使用命令 hostnamectl set-hostname node1 来修改 hostname。

禁用防火墙:

➜  ~ systemctl stop firewalld
➜ ~ systemctl disable firewalld

禁用 SELINUX:

➜  ~ setenforce 0
➜ ~ cat /etc/selinux/config
SELINUX=disabled

由于开启内核 ipv4 转发需要加载 br_netfilter 模块,所以加载下该模块:

➜  ~ modprobe br_netfilter

最好将上面的命令设置成开机启动,因为重启后模块失效,下面是开机自动加载模块的方式。首先新建 /etc/rc.sysinit 文件,内容如下所示:

#!/bin/bash
for file in /etc/sysconfig/modules/*.modules ; do
[ -x $file ] && $file
done

然后在 /etc/sysconfig/modules/ 目录下新建如下文件:

➜  ~ cat /etc/sysconfig/modules/br_netfilter.modules
modprobe br_netfilter

增加权限:

➜  ~ chmod 755 br_netfilter.modules

然后重启后,模块就可以自动加载了:

➜  ~ lsmod |grep br_netfilter
br_netfilter 22209 0
bridge 136173 1 br_netfilter

创建 /etc/sysctl.d/k8s.conf文件,添加如下内容:

net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
# 下面的内核参数可以解决ipvs模式下长连接空闲超时的问题
net.ipv4.tcp_keepalive_intvl = 30
net.ipv4.tcp_keepalive_probes = 10
net.ipv4.tcp_keepalive_time = 600
信息

bridge-nf 使得 netfilter 可以对 Linux 网桥上的 IPv4/ARP/IPv6 包过滤。比如,设置net.bridge.bridge-nf-call-iptables=1后,二层的网桥在转发包时也会被 iptables 的 FORWARD 规则所过滤。常用的选项包括:

  • net.bridge.bridge-nf-call-arptables:是否在 arptables 的 FORWARD 中过滤网桥的 ARP 包
  • net.bridge.bridge-nf-call-ip6tables:是否在 ip6tables 链中过滤 IPv6 包
  • net.bridge.bridge-nf-call-iptables:是否在 iptables 链中过滤 IPv4 包
  • net.bridge.bridge-nf-filter-vlan-tagged:是否在 iptables/arptables 中过滤打了 vlan 标签的包。 :::

执行如下命令使修改生效:

➜  ~ sysctl -p /etc/sysctl.d/k8s.conf

安装 ipvs:

/etc/sysconfig/modules/ipvs.modules
➜  ~ cat > /etc/sysconfig/modules/ipvs.modules <<EOF
#!/bin/bash
modprobe -- ip_vs
modprobe -- ip_vs_rr
modprobe -- ip_vs_wrr
modprobe -- ip_vs_sh
modprobe -- nf_conntrack_ipv4
EOF
➜ ~ chmod 755 /etc/sysconfig/modules/ipvs.modules && bash /etc/sysconfig/modules/ipvs.modules && lsmod | grep -e ip_vs -e nf_conntrack_ipv4

上面脚本创建了的 /etc/sysconfig/modules/ipvs.modules文件,保证在节点重启后能自动加载所需模块。使用 lsmod | grep -e ip_vs -e nf_conntrack_ipv4命令查看是否已经正确加载所需的内核模块。

接下来还需要确保各个节点上已经安装了 ipset 软件包:

➜  ~ yum install ipset

为了便于查看 ipvs 的代理规则,最好安装一下管理工具 ipvsadm:

➜  ~ yum install ipvsadm

同步服务器时间

➜  ~ yum install chrony -y
➜ ~ systemctl enable chronyd
➜ ~ systemctl start chronyd
➜ ~ chronyc sources
210 Number of sources = 4
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
^+ sv1.ggsrv.de 2 6 17 32 -823us[-1128us] +/- 98ms
^- montreal.ca.logiplex.net 2 6 17 32 -17ms[ -17ms] +/- 179ms
^- ntp6.flashdance.cx 2 6 17 32 -32ms[ -32ms] +/- 161ms
^* 119.28.183.184 2 6 33 32 +661us[ +357us] +/- 38ms
➜ ~ date
Tue Aug 31 14:36:14 CST 2021

关闭 swap 分区:

➜  ~ swapoff -a

修改 /etc/fstab文件,注释掉 SWAP 的自动挂载,使用 free -m确认 swap 已经关闭。swappiness 参数调整,修改 /etc/sysctl.d/k8s.conf添加下面一行:

vm.swappiness=0

执行 sysctl -p /etc/sysctl.d/k8s.conf 使修改生效。

安装 Containerd

我们已经了解过容器运行时 containerd 的一些基本使用,接下来在各个节点上安装 Containerd。

如果这安装集群的过程出现了容器运行时的问题,启动不起来,可以尝试使用 yum install containerd.io 来安装 Containerd。

首先需要这节点商安装 seccomp 依赖:

➜  ~ rpm -qa |grep libseccomp
libseccomp-2.3.1-4.el7.x86_64
# 如果没有安装 libseccomp 包则执行下面的命令安装依赖
➜ ~ yum install wget -y
➜ ~ wget http://mirror.centos.org/centos/7/os/x86_64/Packages/libseccomp-2.3.1-4.el7.x86_64.rpm
➜ ~ yum install libseccomp-2.3.1-4.el7.x86_64.rpm -y

由于 containerd 需要调用 runc,所以我们也需要先安装 runc,不过 containerd 提供了一个包含相关依赖的压缩包 cri-containerd-cni-${VERSION}.${OS}-${ARCH}.tar.gz,可以直接使用这个包来进行安装。首先从 release 页面下载最新版本的压缩包,当前为 1.5.5 版本(最新的 1.5.7 版本在 CentOS7 下面执行 runc 会报错:https://github.com/containerd/containerd/issues/6091):

➜  ~ wget https://github.com/containerd/containerd/releases/download/v1.5.5/cri-containerd-cni-1.5.5-linux-amd64.tar.gz
# 如果有限制,也可以替换成下面的 URL 加速下载
# wget https://download.fastgit.org/containerd/containerd/releases/download/v1.5.5/cri-containerd-cni-1.5.5-linux-amd64.tar.gz

可以通过 tar 的 -t 选项直接看到压缩包中包含哪些文件:

由于 containerd 需要调用 runc,所以我们也需要先安装 runc,不过 containerd 提供了一个包含相关依赖的压缩包 cri-containerd-cni-${VERSION}.${OS}-${ARCH}.tar.gz,可以直接使用这个包来进行安装。首先从 release 页面下载最新版本的压缩包,当前为 1.5.5 版本:

➜  ~ wget https://github.com/containerd/containerd/releases/download/v1.5.5/cri-containerd-cni-1.5.5-linux-amd64.tar.gz
# 如果有限制,也可以替换成下面的 URL 加速下载
# wget https://download.fastgit.org/containerd/containerd/releases/download/v1.5.5/cri-containerd-cni-1.5.5-linux-amd64.tar.gz

直接将压缩包解压到系统的各个目录中:

➜  ~ tar -C / -xzf cri-containerd-cni-1.5.5-linux-amd64.tar.gz

然后要将 /usr/local/bin/usr/local/sbin 追加到 ~/.bashrc 文件的 PATH 环境变量中:

export PATH=$PATH:/usr/local/bin:/usr/local/sbin

然后执行下面的命令使其立即生效:

➜  ~ source ~/.bashrc

containerd 的默认配置文件为 /etc/containerd/config.toml,我们可以通过如下所示的命令生成一个默认的配置:

➜  ~ mkdir -p /etc/containerd
➜ ~ containerd config default > /etc/containerd/config.toml

对于使用 systemd 作为 init system 的 Linux 的发行版,使用 systemd 作为容器的 cgroup driver 可以确保节点在资源紧张的情况更加稳定,所以推荐将 containerd 的 cgroup driver 配置为 systemd。

修改前面生成的配置文件 /etc/containerd/config.toml,在 plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc.options 配置块下面将 SystemdCgroup 设置为 true

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

然后再为镜像仓库配置一个加速器,需要在 cri 配置块下面的 registry 配置块下面进行配置 registry.mirrors

[plugins."io.containerd.grpc.v1.cri"]
...
# sandbox_image = "k8s.gcr.io/pause:3.5"
sandbox_image = "registry.aliyuncs.com/k8sxio/pause:3.5"
...
[plugins."io.containerd.grpc.v1.cri".registry]
[plugins."io.containerd.grpc.v1.cri".registry.mirrors]
[plugins."io.containerd.grpc.v1.cri".registry.mirrors."docker.io"]
endpoint = ["https://bqr1dr1n.mirror.aliyuncs.com"]
[plugins."io.containerd.grpc.v1.cri".registry.mirrors."k8s.gcr.io"]
endpoint = ["https://registry.aliyuncs.com/k8sxio"]

如果我们的节点不能正常获取 k8s.gcr.io 的镜像,那么我们需要在上面重新配置 sandbox_image 镜像,否则后面 kubelet 覆盖该镜像不会生效:Warning: For remote container runtime, --pod-infra-container-image is ignored in kubelet, which should be set in that remote runtime instead

由于上面我们下载的 containerd 压缩包中包含一个 etc/systemd/system/containerd.service 的文件,这样我们就可以通过 systemd 来配置 containerd 作为守护进程运行了,现在我们就可以启动 containerd 了,直接执行下面的命令即可:

➜  ~ systemctl daemon-reload
➜ ~ systemctl enable containerd --now

启动完成后就可以使用 containerd 的本地 CLI 工具 ctrcrictl 了,比如查看版本:

➜  ~ ctr version
Client:
Version: v1.5.5
Revision: 72cec4be58a9eb6b2910f5d10f1c01ca47d231c0
Go version: go1.16.6

Server:
Version: v1.5.5
Revision: 72cec4be58a9eb6b2910f5d10f1c01ca47d231c0
UUID: cd2894ad-fd71-4ef7-a09f-5795c7eb4c3b
➜ ~ crictl version
Version: 0.1.0
RuntimeName: containerd
RuntimeVersion: v1.5.5
RuntimeApiVersion: v1alpha2

使用 kubeadm 部署 Kubernetes

上面的相关环境配置也完成了,现在我们就可以来安装 Kubeadm 了,我们这里是通过指定 yum 源的方式来进行安装的:

➜  ~ 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
EOF

当然了,上面的 yum 源是需要科学上网的,如果不能科学上网的话,我们可以使用阿里云的源进行安装:

➜  ~ 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

然后安装 kubeadm、kubelet、kubectl:

# --disableexcludes 禁掉除了kubernetes之外的别的仓库
➜ ~ yum makecache fast
➜ ~ yum install -y kubelet-1.22.2 kubeadm-1.22.2 kubectl-1.22.2 --disableexcludes=kubernetes
➜ ~ kubeadm version
kubeadm version: &version.Info{Major:"1", Minor:"22", GitVersion:"v1.22.2", GitCommit:"8b5a19147530eaac9476b0ab82980b4088bbc1b2", GitTreeState:"clean", BuildDate:"2021-09-15T21:37:34Z", GoVersion:"go1.16.8", Compiler:"gc", Platform:"linux/amd64"}

可以看到我们这里安装的是 v1.22.2 版本,然后将 master 节点的 kubelet 设置成开机启动:

➜  ~ systemctl enable --now kubelet

到这里为止上面所有的操作都需要在所有节点执行配置。

初始化集群

当我们执行 kubelet --help 命令的时候可以看到原来大部分命令行参数都被 DEPRECATED了,这是因为官方推荐我们使用 --config 来指定配置文件,在配置文件中指定原来这些参数的配置,可以通过官方文档 Set Kubelet parameters via a config file 了解更多相关信息,这样 Kubernetes 就可以支持动态 Kubelet 配置(Dynamic Kubelet Configuration)了,参考 Reconfigure a Node’s Kubelet in a Live Cluster

然后我们可以通过下面的命令在 master 节点上输出集群初始化默认使用的配置:

➜  ~ kubeadm config print init-defaults --component-configs KubeletConfiguration > kubeadm.yaml

然后根据我们自己的需求修改配置,比如修改 imageRepository 指定集群初始化时拉取 Kubernetes 所需镜像的地址,kube-proxy 的模式为 ipvs,另外需要注意的是我们这里是准备安装 flannel 网络插件的,需要将 networking.podSubnet 设置为 10.244.0.0/16

kubeadm.yaml
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: 192.168.31.31 # 指定master节点内网IP
bindPort: 6443
nodeRegistration:
criSocket: /run/containerd/containerd.sock # 使用 containerd的Unix socket 地址
imagePullPolicy: IfNotPresent
name: master
taints: # 给master添加污点,master节点不能调度应用
- effect: 'NoSchedule'
key: 'node-role.kubernetes.io/master'

---
apiVersion: kubeproxy.config.k8s.io/v1alpha1
kind: KubeProxyConfiguration
mode: ipvs # kube-proxy 模式

---
apiServer:
timeoutForControlPlane: 4m0s
apiVersion: kubeadm.k8s.io/v1beta3
certificatesDir: /etc/kubernetes/pki
clusterName: kubernetes
controllerManager: {}
dns: {}
etcd:
local:
dataDir: /var/lib/etcd
imageRepository: registry.aliyuncs.com/k8sxio
kind: ClusterConfiguration
kubernetesVersion: 1.22.2
networking:
dnsDomain: cluster.local
serviceSubnet: 10.96.0.0/12
podSubnet: 10.244.0.0/16 # 指定 pod 子网
scheduler: {}

---
apiVersion: kubelet.config.k8s.io/v1beta1
authentication:
anonymous:
enabled: false
webhook:
cacheTTL: 0s
enabled: true
x509:
clientCAFile: /etc/kubernetes/pki/ca.crt
authorization:
mode: Webhook
webhook:
cacheAuthorizedTTL: 0s
cacheUnauthorizedTTL: 0s
clusterDNS:
- 10.96.0.10
clusterDomain: cluster.local
cpuManagerReconcilePeriod: 0s
evictionPressureTransitionPeriod: 0s
fileCheckFrequency: 0s
healthzBindAddress: 127.0.0.1
healthzPort: 10248
httpCheckFrequency: 0s
imageMinimumGCAge: 0s
kind: KubeletConfiguration
cgroupDriver: systemd # 配置 cgroup driver
logging: {}
memorySwap: {}
nodeStatusReportFrequency: 0s
nodeStatusUpdateFrequency: 0s
rotateCertificates: true
runtimeRequestTimeout: 0s
shutdownGracePeriod: 0s
shutdownGracePeriodCriticalPods: 0s
staticPodPath: /etc/kubernetes/manifests
streamingConnectionIdleTimeout: 0s
syncFrequency: 0s
volumeStatsAggPeriod: 0s

对于上面的资源清单的文档比较杂,要想完整了解上面的资源对象对应的属性,可以查看对应的 godoc 文档,地址:https://godoc.org/k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1beta3。 :::

在开始初始化集群之前可以使用 kubeadm config images pull --config kubeadm.yaml 预先在各个服务器节点上拉取所 k8s 需要的容器镜像。

配置文件准备好过后,可以使用如下命令先将相关镜像 pull 下面:

➜  ~ kubeadm config images pull --config kubeadm.yaml
[config/images] Pulled registry.aliyuncs.com/k8sxio/kube-apiserver:v1.22.2
[config/images] Pulled registry.aliyuncs.com/k8sxio/kube-controller-manager:v1.22.2
[config/images] Pulled registry.aliyuncs.com/k8sxio/kube-scheduler:v1.22.2
[config/images] Pulled registry.aliyuncs.com/k8sxio/kube-proxy:v1.22.2
[config/images] Pulled registry.aliyuncs.com/k8sxio/pause:3.5
[config/images] Pulled registry.aliyuncs.com/k8sxio/etcd:3.5.0-0
failed to pull image "registry.aliyuncs.com/k8sxio/coredns:v1.8.4": output: time="2021-10-25T17:34:48+08:00" level=fatal msg="pulling image: rpc error: code = NotFound desc = failed to pull and unpack image \"registry.aliyuncs.com/k8sxio/coredns:v1.8.4\": failed to resolve reference \"registry.aliyuncs.com/k8sxio/coredns:v1.8.4\": registry.aliyuncs.com/k8sxio/coredns:v1.8.4: not found"
, error: exit status 1
To see the stack trace of this error execute with --v=5 or higher

上面在拉取 coredns 镜像的时候出错了,没有找到这个镜像,我们可以手动 pull 该镜像,然后重新 tag 下镜像地址即可:

➜  ~ ctr -n k8s.io i pull docker.io/coredns/coredns:1.8.4
docker.io/coredns/coredns:1.8.4: resolved |++++++++++++++++++++++++++++++++++++++|
index-sha256:6e5a02c21641597998b4be7cb5eb1e7b02c0d8d23cce4dd09f4682d463798890: done |++++++++++++++++++++++++++++++++++++++|
manifest-sha256:10683d82b024a58cc248c468c2632f9d1b260500f7cd9bb8e73f751048d7d6d4: done |++++++++++++++++++++++++++++++++++++++|
layer-sha256:bc38a22c706b427217bcbd1a7ac7c8873e75efdd0e59d6b9f069b4b243db4b4b: done |++++++++++++++++++++++++++++++++++++++|
config-sha256:8d147537fb7d1ac8895da4d55a5e53621949981e2e6460976dae812f83d84a44: done |++++++++++++++++++++++++++++++++++++++|
layer-sha256:c6568d217a0023041ef9f729e8836b19f863bcdb612bb3a329ebc165539f5a80: exists |++++++++++++++++++++++++++++++++++++++|
elapsed: 12.4s total: 12.0 M (991.3 KiB/s)
unpacking linux/amd64 sha256:6e5a02c21641597998b4be7cb5eb1e7b02c0d8d23cce4dd09f4682d463798890...
done: 410.185888ms
➜ ~ ctr -n k8s.io i tag docker.io/coredns/coredns:1.8.4 registry.aliyuncs.com/k8sxio/coredns:v1.8.4

然后就可以使用上面的配置文件在 master 节点上进行初始化:

➜  ~ kubeadm init --config kubeadm.yaml
[init] Using Kubernetes version: v1.22.2
[preflight] Running pre-flight checks
[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'
[certs] Using certificateDir folder "/etc/kubernetes/pki"
[certs] Generating "ca" certificate and key
[certs] Generating "apiserver" certificate and key
[certs] apiserver serving cert is signed for DNS names [kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local master1] and IPs [10.96.0.1 192.168.31.31]
[certs] Generating "apiserver-kubelet-client" certificate and key
[certs] Generating "front-proxy-ca" certificate and key
[certs] Generating "front-proxy-client" certificate and key
[certs] Generating "etcd/ca" certificate and key
[certs] Generating "etcd/server" certificate and key
[certs] etcd/server serving cert is signed for DNS names [localhost master1] and IPs [192.168.31.31 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [localhost master1] and IPs [192.168.31.31 127.0.0.1 ::1]
[certs] Generating "etcd/healthcheck-client" certificate and key
[certs] Generating "apiserver-etcd-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
[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] Starting the kubelet
[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 12.004224 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.22" in namespace kube-system with the configuration for the kubelets in the cluster
[upload-certs] Skipping phase. Please see --upload-certs
[mark-control-plane] Marking the node master1 as control-plane by adding the labels: [node-role.kubernetes.io/master(deprecated) node-role.kubernetes.io/control-plane node.kubernetes.io/exclude-from-external-load-balancers]
[mark-control-plane] Marking the node master1 as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: abcdef.0123456789abcdef
[bootstrap-token] Configuring bootstrap tokens, cluster-info ConfigMap, RBAC Roles
[bootstrap-token] configured RBAC rules to allow Node Bootstrap tokens to get nodes
[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
[kubelet-finalize] Updating "/etc/kubernetes/kubelet.conf" to point to a rotatable kubelet client certificate and key
[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

Alternatively, if you are the root user, you can run:

export KUBECONFIG=/etc/kubernetes/admin.conf

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 192.168.31.31:6443 --token abcdef.0123456789abcdef \
--discovery-token-ca-cert-hash sha256:ca0c87226c69309d7779096c15b6a41e14b077baf4650bfdb6f9d3178d4da645

根据安装提示拷贝 kubeconfig 文件:

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

然后可以使用 kubectl 命令查看 master 节点已经初始化成功了:

➜  ~ kubectl get nodes
NAME STATUS ROLES AGE VERSION
master1 Ready control-plane,master 41s v1.22.2

添加节点

记住初始化集群上面的配置和操作要提前做好,将 master 节点上面的 $HOME/.kube/config 文件拷贝到 node 节点对应的文件中,安装 kubeadm、kubelet、kubectl(可选),然后执行上面初始化完成后提示的 join 命令即可:

➜  ~ kubeadm join 192.168.31.31:6443 --token abcdef.0123456789abcdef \
> --discovery-token-ca-cert-hash sha256:ca0c87226c69309d7779096c15b6a41e14b077baf4650bfdb6f9d3178d4da645
[preflight] Running pre-flight checks
[preflight] Reading configuration from the cluster...
[preflight] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
[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] Starting the kubelet
[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.

重新获取 join 命令

如果忘记了上面的 join 命令可以使用命令kubeadm token create --print-join-command 重新获取。

执行成功后运行 get nodes 命令:

➜  ~ kubectl get nodes
NAME STATUS ROLES AGE VERSION
master1 Ready control-plane,master 2m35s v1.22.2
node1 Ready <none> 45s v1.22.2

这个时候其实集群还不能正常使用,因为还没有安装网络插件,接下来安装网络插件,可以在文档 https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/ 中选择我们自己的网络插件,这里我们安装 flannel:

➜  ~ wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
# 如果有节点是多网卡,则需要在资源清单文件中指定内网网卡
# 搜索到名为 kube-flannel-ds 的 DaemonSet,在kube-flannel容器下面
➜ ~ vi kube-flannel.yml
......
containers:
- name: kube-flannel
image: quay.io/coreos/flannel:v0.15.0
command:
- /opt/bin/flanneld
args:
- --ip-masq
- --kube-subnet-mgr
- --iface=eth0 # 如果是多网卡的话,指定内网网卡的名称
......
➜ ~ kubectl apply -f kube-flannel.yml # 安装 flannel 网络插件

隔一会儿查看 Pod 运行状态:

➜  ~ kubectl get pods -n kube-system
NAME READY STATUS RESTARTS AGE
coredns-7568f67dbd-5mg59 1/1 Running 0 8m32s
coredns-7568f67dbd-b685t 1/1 Running 0 8m31s
etcd-master 1/1 Running 0 66m
kube-apiserver-master 1/1 Running 0 66m
kube-controller-manager-master 1/1 Running 0 66m
kube-flannel-ds-dsbt6 1/1 Running 0 11m
kube-flannel-ds-zwlm6 1/1 Running 0 11m
kube-proxy-jq84n 1/1 Running 0 66m
kube-proxy-x4hbv 1/1 Running 0 19m
kube-scheduler-master 1/1 Running 0 66m
信息

当我们部署完网络插件后执行 ifconfig 命令,正常会看到新增的cni0flannel1这两个虚拟设备,但是如果没有看到 cni0这个设备也不用太担心,我们可以观察 /var/lib/cni目录是否存在,如果不存在并不是说部署有问题,而是该节点上暂时还没有应用运行,我们只需要在该节点上运行一个 Pod 就可以看到该目录会被创建,并且 cni0设备也会被创建出来。

用同样的方法添加另外一个节点即可。

Dashboard

v1.22.2 版本的集群需要安装最新的 2.0+ 版本的 Dashboard:

# 推荐使用下面这种方式
➜ ~ wget https://raw.githubusercontent.com/kubernetes/dashboard/v2.3.1/aio/deploy/recommended.yaml
➜ ~ vi recommended.yaml
# 修改Service为NodePort类型
......
kind: Service
apiVersion: v1
metadata:
labels:
k8s-app: kubernetes-dashboard
name: kubernetes-dashboard
namespace: kubernetes-dashboard
spec:
ports:
- port: 443
targetPort: 8443
selector:
k8s-app: kubernetes-dashboard
type: NodePort # 加上type=NodePort变成NodePort类型的服务
......
信息

在 YAML 文件中可以看到新版本 Dashboard 集成了一个 metrics-scraper 的组件,可以通过 Kubernetes 的 Metrics API 收集一些基础资源的监控信息,并在 web 页面上展示,所以要想在页面上展示监控信息就需要提供 Metrics API,比如安装 Metrics Server。

直接创建:

➜  ~ kubectl apply -f recommended.yaml

新版本的 Dashboard 会被默认安装在 kubernetes-dashboard 这个命名空间下面:

➜  ~ kubectl get pods -n kubernetes-dashboard -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
dashboard-metrics-scraper-856586f554-pllvt 1/1 Running 0 24m 10.88.0.7 master <none> <none>
kubernetes-dashboard-76597d7df5-82998 1/1 Running 0 21m 10.88.0.2 node2 <none> <none>

我们仔细看可以发现上面的 Pod 分配的 IP 段是 10.88.xx.xx,包括前面自动安装的 CoreDNS 也是如此,我们前面不是配置的 podSubnet 为 10.244.0.0/16 吗?我们先去查看下 CNI 的配置文件:

➜  ~ ls -la /etc/cni/net.d/
total 8
drwxr-xr-x 2 1001 docker 67 Aug 31 16:45 .
drwxr-xr-x. 3 1001 docker 19 Jul 30 01:13 ..
-rw-r--r-- 1 1001 docker 604 Jul 30 01:13 10-containerd-net.conflist
-rw-r--r-- 1 root root 292 Aug 31 16:45 10-flannel.conflist

可以看到里面包含两个配置,一个是 10-containerd-net.conflist,另外一个是我们上面创建的 Flannel 网络插件生成的配置,我们的需求肯定是想使用 Flannel 的这个配置,我们可以查看下 containerd 这个自带的 cni 插件配置:

➜  ~ cat /etc/cni/net.d/10-containerd-net.conflist
{
"cniVersion": "0.4.0",
"name": "containerd-net",
"plugins": [
{
"type": "bridge",
"bridge": "cni0",
"isGateway": true,
"ipMasq": true,
"promiscMode": true,
"ipam": {
"type": "host-local",
"ranges": [
[{
"subnet": "10.88.0.0/16"
}],
[{
"subnet": "2001:4860:4860::/64"
}]
],
"routes": [
{ "dst": "0.0.0.0/0" },
{ "dst": "::/0" }
]
}
},
{
"type": "portmap",
"capabilities": {"portMappings": true}
}
]
}

可以看到上面的 IP 段恰好就是 10.88.0.0/16,但是这个 cni 插件类型是 bridge 网络,网桥的名称为 cni0

➜  ~ ip a
...
6: cni0: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 9a:e7:eb:40:e8:66 brd ff:ff:ff:ff:ff:ff
inet 10.88.0.1/16 brd 10.88.255.255 scope global cni0
valid_lft forever preferred_lft forever
inet6 2001:4860:4860::1/64 scope global
valid_lft forever preferred_lft forever
inet6 fe80::98e7:ebff:fe40:e866/64 scope link
valid_lft forever preferred_lft forever
...

但是使用 bridge 网络的容器无法跨多个宿主机进行通信,跨主机通信需要借助其他的 cni 插件,比如上面我们安装的 Flannel,或者 Calico 等等,由于我们这里有两个 cni 配置,所以我们需要将 10-containerd-net.conflist 这个配置删除,因为如果这个目录中有多个 cni 配置文件,kubelet 将会使用按文件名的字典顺序排列的第一个作为配置文件,所以前面默认选择使用的是 containerd-net 这个插件。

➜  ~ mv /etc/cni/net.d/10-containerd-net.conflist /etc/cni/net.d/10-containerd-net.conflist.bak
➜ ~ ifconfig cni0 down && ip link delete cni0
➜ ~ systemctl daemon-reload
➜ ~ systemctl restart containerd kubelet

然后记得重建 coredns 和 dashboard 的 Pod,重建后 Pod 的 IP 地址就正常了:

➜  ~ kubectl get pods -n kubernetes-dashboard -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
dashboard-metrics-scraper-856586f554-tp8m5 1/1 Running 0 42s 10.244.1.6 node2 <none> <none>
kubernetes-dashboard-76597d7df5-9rmbx 1/1 Running 0 66s 10.244.1.5 node2 <none> <none>
➜ ~ kubectl get pods -n kube-system -o wide -l k8s-app=kube-dns
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
coredns-7568f67dbd-n7bfx 1/1 Running 0 5m40s 10.244.1.2 node2 <none> <none>
coredns-7568f67dbd-plrv8 1/1 Running 0 3m47s 10.244.1.4 node2 <none> <none>

查看 Dashboard 的 NodePort 端口:

➜  ~ kubectl get svc -n kubernetes-dashboard
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
dashboard-metrics-scraper ClusterIP 10.99.37.172 <none> 8000/TCP 25m
kubernetes-dashboard NodePort 10.103.102.27 <none> 443:31050/TCP 25m

然后可以通过上面的 31050 端口去访问 Dashboard,要记住使用 https,Chrome 不生效可以使用 Firefox 测试,如果没有 Firefox 下面打不开页面,可以点击下页面中的 信任证书即可:

信任证书

信任后就可以访问到 Dashboard 的登录页面了:

k8s dashboard login

然后创建一个具有全局所有权限的用户来登录 Dashboard:(admin.yaml)

kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
name: admin
roleRef:
kind: ClusterRole
name: cluster-admin
apiGroup: rbac.authorization.k8s.io
subjects:
- kind: ServiceAccount
name: admin
namespace: kubernetes-dashboard
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: admin
namespace: kubernetes-dashboard

直接创建:

➜  ~ kubectl apply -f admin.yaml
➜ ~ kubectl get secret -n kubernetes-dashboard|grep admin-token
admin-token-lwmmx kubernetes.io/service-account-token 3 1d
➜ ~ kubectl get secret admin-token-lwmmx -o jsonpath={.data.token} -n kubernetes-dashboard |base64 -d
# 会生成一串很长的base64后的字符串

然后用上面的 base64 解码后的字符串作为 token 登录 Dashboard 即可,新版本还新增了一个暗黑模式:

k8s dashboard

最终我们就完成了使用 kubeadm 搭建 v1.22.1 版本的 kubernetes 集群、coredns、ipvs、flannel、containerd。

清理

如果你的集群安装过程中遇到了其他问题,我们可以使用下面的命令来进行重置:

➜  ~ kubeadm reset
➜ ~ ifconfig cni0 down && ip link delete cni0
➜ ~ ifconfig flannel.1 down && ip link delete flannel.1
➜ ~ rm -rf /var/lib/cni/