前言
当Kubernetes社区宣布1.20版本之后会逐步弃用 dockershim ，当时也有很多自媒体在宣 传Kubernetes弃用Docker。其实，我觉得这是一种误导，也许仅仅是为了蹭热度。 dockershim 是Kubernetes的一个组件，其作用是为了操作Docker。Docker是在2013年面世的，而 Kubernetes是在2016年，所以Docker刚开始并没有想到编排，也不会知道会出现Kubernetes这个庞然大 物（它要是知道，也不会败的那么快...）。但是Kubernetes在创建的时候就是以Docker作为容器运行 时，很多操作逻辑都是针对的Docker，随着社区越来越健壮，为了兼容更多的容器运行时，才将Docker 的相关逻辑独立出来组成了 dockershim 。 正因为这样，只要Kubernetes的任何变动或者Docker的任何变动，都必须维护 dockershim ，这样才能 保证足够的支持，但是通过 dockershim 操作Docker，其本质还是操作Docker的底层运行时 Containerd ，而且 Containerd 自身也是支持 CRI （Container Runtime Interface），那为什么还要 绕一层Docker呢？是不是可以直接通过 CRI 和 Containerd 进行交互？这也是社区希望启动 dockershim 的原因之一吧。 那什么是Containerd呢？ Containerd是从Docker中分离的一个项目，旨在为Kubernetes提供容器运行时，负责管理镜像和容器的 生命周期。不过Containerd是可以抛开Docker独立工作的。它的特性如下： 支持OCI镜像规范，也就是runc 支持OCI运行时规范 支持镜像的pull 支持容器网络管理 存储支持多租户 支持容器运行时和容器的生命周期管理 支持管理网络名称空间 Containerd和Docker在命令使用上的一些区别主要如下：
可以看到使用方式大同小异。
下面介绍一下使用kubeadm安装K8S集群，并使用containerd作为容器运行时的具体安装步骤。
一、环境说明
主机节点
| 服务器系统 | 节点IP | 节点类型 | CUP/内存 | Hostname | 内核 |
| Centos 7.9.2009 | 192.168.1.92 | 主节点 | 2核/4G | master | 3.10.0 |
| Centos 7.9.2009 | 192.168.1.93 | 工作节点1 | 2核/4G | node1 | 3.10.0 |
| Centos 7.9.2009 | 192.168.1.94 | 工作节点2 | 2核/4G | node2 | 3.10.0 |
软件说明
| 软件 | 版本 |
| kubernetes | v1.25.0 |
| containerd | 1.6.10 |
二、环境准备
注：所有节点上执行------------------------开始----------------------------
2.1 修改hostname
hostnamectl set-hostname master hostnamectl set-hostname node1 hostnamectl set-hostname node2
2.2 三台机器网络连通（修改所有节点）
[root@master ~]# cat /etc/hosts 192.168.1.92 master 192.168.1.93 node1 192.168.1.94 node2
2.3 关闭防火墙
systemctl stop firewalld && systemctl disable firewalld && systemctl status firewalld
2.4 关闭selinux
setenforce 0 sed -i 's/^SELINUX=enforcing$/SELINUX=disabled/' /etc/selinux/config
2.5 关闭swap
- 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。
swapoff -a sed -i '/swap/s/^\(.*\)$/#\1/g' /etc/fstab
2.6 配置iptables的ACCEPT规则
iptables -F && iptables -X && iptables -F -t nat && iptables -X -t nat && iptables -P FORWARD ACCEPT
2.7 设置系统参数
- swappiness 参数调整，swap关闭，也必须添加此参数
cat <<EOF > /etc/sysctl.d/k8s.conf vm.swappiness = 0 net.bridge.bridge-nf-call-ip6tables = 1 net.bridge.bridge-nf-call-iptables = 1 net.ipv4.ip_forward = 1 EOF
2.8 执行如下命令使修改生效
modprobe br_netfilter sysctl -p /etc/sysctl.d/k8s.conf
2.9 安装 ipvs
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。
[root@node1 ~]# lsmod | grep -e ip_vs -e nf_conntrack_ipv4 nf_conntrack_ipv4 15053 19 nf_defrag_ipv4 12729 1 nf_conntrack_ipv4 ip_vs_sh 12688 0 ip_vs_wrr 12697 0 ip_vs_rr 12600 4 ip_vs 145458 10 ip_vs_rr,ip_vs_sh,ip_vs_wrr nf_conntrack 139264 10 ip_vs,nf_nat,nf_nat_ipv4,nf_nat_ipv6,xt_conntrack,nf_nat_masquerade_ipv4,nf_nat_masquerade_ipv6,nf_conntrack_netlink,nf_conntrack_ipv4,nf_conntrack_ipv6 libcrc32c 12644 4 xfs,ip_vs,nf_nat,nf_conntrack
三、安装 ipset 软件包
3.1 安装 ipset 软件包
yum install ipset -y
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 -y
3.2 同步服务器时间
yum install chrony -y systemctl enable chronyd systemctl start chronyd chronyc sources
四、安装 contained
4.1 下载源码库
wget -O /etc/yum.repos.d/docker-ce.repo https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
4.2 安装containerd
# 查看可安装版本 [root@master ~]# yum list | grep containerd containerd.io.x86_64 1.6.10-3.1.el7 @docker-ce-stable # 执行安装 [root@master ~]# yum -y install containerd.io # 查看 [root@master ~]# rpm -qa | grep containerd containerd.io-1.6.10-3.1.el7.x86_64
4.3 创建containerd配置文件
# 创建目录 mkdir -p /etc/containerd containerd config default > /etc/containerd/config.toml # 替换配置文件 sed -i 's#SystemdCgroup = false#SystemdCgroup = true#' /etc/containerd/config.toml sed -i 's#sandbox_image = "registry.k8s.io/pause:3.6"#sandbox_image = "registry.aliyuncs.com/google_containers/pause:3.6"#' /etc/containerd/config.toml
4.4 启动containerd
systemctl enable containerd systemctl start containerd systemctl status containerd
4.5 验证
[root@master ~]# ctr version Client: Version: 1.6.10 Revision: 770bd0108c32f3fb5c73ae1264f7e503fe7b2661 Go version: go1.18.8 Server: Version: 1.6.10 Revision: 770bd0108c32f3fb5c73ae1264f7e503fe7b2661 UUID: 10b91012-6b24-4059-bf92-d71d269a5fbc
五、安装三大件（ kubelet、kubeadm、kubectl）
在确保 Containerd安装完成后，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。
5.1 下载 kubernetes 源码库
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
5.2 安装 kubeadm、kubelet、kubectl（我安装的指定版本1.25.0，有版本要求自己设定版本）
yum install -y kubelet-1.25.0 kubeadm-1.25.0 kubectl-1.25.0
5.3 设置运行时
crictl config runtime-endpoint /run/containerd/containerd.sock
5.4 可以看到我们这里安装的是 v1.25.0版本，将 kubelet 设置成开机启动
systemctl daemon-reload systemctl enable kubelet && systemctl start kubelet
注：所有节点上执行------------------------结束----------------------------
六、初始化集群
初始化master（master执行）6.1 然后接下来在 master 节点配置 kubeadm 初始化文件，可以通过如下命令导出默认的初始化配置：
kubeadm config print init-defaults > kubeadm.yaml
然后根据我们自己的需求修改配置，比如修改 imageRepository 的值，kube-proxy 的模式为 ipvs，需要 注意的是由于我们使用的containerd作为运行时，所以在初始化节点的时候需要指定 cgroupDriver 为
systemd。6.2 修改内容：
- advertiseAddress: 192.168.1.92 # 修改为自己的master节点IP
- name: master # 修改为master主机名
- imageRepository: registry.cn-hangzhou.aliyuncs.com/google_containers # 修改为阿里云镜像地址
- kubernetesVersion: 1.25.0 # 确认是否为要安装版本，版本根据执行：kubelet --version 得来
- podSubnet: 172.16.0.0/16 # networking: 下添加pod网络
- scheduler: {} # 添加模式为 ipvs
- cgroupDriver: systemd # 指定 cgroupDriver 为 systemd
[root@master ~]# cat 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: 192.168.1.92
bindPort: 6443
nodeRegistration:
criSocket: unix:///var/run/containerd/containerd.sock
imagePullPolicy: IfNotPresent
name: master
taints: null
---
apiServer:
timeoutForControlPlane: 4m0s
apiVersion: kubeadm.k8s.io/v1beta3
certificatesDir: /etc/kubernetes/pki
clusterName: kubernetes
controllerManager: {}
dns: {}
etcd:
local:
dataDir: /var/lib/etcd
imageRepository: registry.cn-hangzhou.aliyuncs.com/google_containers
kind: ClusterConfiguration
kubernetesVersion: 1.25.0
networking:
dnsDomain: cluster.local
podSubnet: 172.16.0.0/16
serviceSubnet: 10.96.0.0/12
scheduler: {}
---
apiVersion: kubeproxy.config.k8s.io/v1alpha1
kind: KubeProxyConfiguration
mode: ipvs
---
apiVersion: kubelet.config.k8s.io/v1beta1
kind: KubeletConfiguration
cgroupDriver: systemd
6.3 使用上面的配置文件进行初始化
kubeadm init --config=kubeadm.yaml
【
注意：CPU核心必须大于1
必须关闭Swap区(临时，永久)
】
[init] Using Kubernetes version: v1.25.0
[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
.........
[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 192.168.1.92:6443 --token abcdef.0123456789abcdef \
--discovery-token-ca-cert-hash sha256:637dedda374472a68d5e3f58701a50527692ab281d50181a7d516751333ea8e8
6.4 执行拷贝 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
6.5 添加节点（node1、node2）
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，然后执行上面初始化完成后提示的 join 命 令即可：- 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。
[root@node1 ~]# kubeadm join 192.168.1.92:6443 --token abcdef.0123456789abcdef \ > --discovery-token-ca-cert-hash sha256:d87669b0c3630a0c5f566097cedee190764712ee0c8d41fc2db00521fcf9f680 [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.
node2:
[root@node2 ~]# kubeadm join 192.168.1.92:6443 --token abcdef.0123456789abcdef \ > --discovery-token-ca-cert-hash sha256:637dedda374472a68d5e3f58701a50527692ab281d50181a7d516751333ea8e8 [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.
6.6 查看集群状态：
[root@master ~]# kubectl get nodes NAME STATUS ROLES AGE VERSION master NotReady control-plane 2m57s v1.25.0 node1 NotReady <none> 47s v1.25.0 node2 NotReady <none> 29s v1.25.0
七、安装网络插件
可以看到是 NotReady 状态，这是因为还没有安装网络插件，必须部署一个 容器网络接口 (CNI) 基于 Pod 网络附加组件，以便您的 Pod 可以相互通信。在安装网络之前，集群 DNS (CoreDNS) 不会启动。接下来安装网络插件，可以在以下两个任一地址中选择需要安装的网络插件(我选用的第二个地址安装)，这里我们安装 calio
- https:// kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/
- https://projectcalico.docs.tigera.io/archive/v3.23/getting-started/kubernetes/self-managed-onprem/onpremises#install-calico
7.1 下载calico文件
[root@master ~]# curl https://projectcalico.docs.tigera.io/archive/v3.23/manifests/calico.yaml -O
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 226k 100 226k 0 0 278k 0 --:--:-- --:--:-- --:--:-- 278k
7.2 编辑calico.yaml文件：
- 注：文件默认IP为：192.168.0.0/16
- name: CALICO_IPV4POOL_CIDR # 由于在init的时候配置的172网段，所以这里需要修改 value: "172.16.0.0/16"
7.3 安装calico网络插件
[root@master ~]# kubectl apply -f calico.yaml configmap/calico-config created customresourcedefinition.apiextensions.k8s.io/bgpconfigurations.crd.projectcalico.org created customresourcedefinition.apiextensions.k8s.io/bgppeers.crd.projectcalico.org created customresourcedefinition.apiextensions.k8s.io/blockaffinities.crd.projectcalico.org created customresourcedefinition.apiextensions.k8s.io/caliconodestatuses.crd.projectcalico.org created customresourcedefinition.apiextensions.k8s.io/clusterinformations.crd.projectcalico.org created customresourcedefinition.apiextensions.k8s.io/felixconfigurations.crd.projectcalico.org created customresourcedefinition.apiextensions.k8s.io/globalnetworkpolicies.crd.projectcalico.org created customresourcedefinition.apiextensions.k8s.io/globalnetworksets.crd.projectcalico.org created customresourcedefinition.apiextensions.k8s.io/hostendpoints.crd.projectcalico.org created customresourcedefinition.apiextensions.k8s.io/ipamblocks.crd.projectcalico.org created customresourcedefinition.apiextensions.k8s.io/ipamconfigs.crd.projectcalico.org created customresourcedefinition.apiextensions.k8s.io/ipamhandles.crd.projectcalico.org created customresourcedefinition.apiextensions.k8s.io/ippools.crd.projectcalico.org created customresourcedefinition.apiextensions.k8s.io/ipreservations.crd.projectcalico.org created customresourcedefinition.apiextensions.k8s.io/kubecontrollersconfigurations.crd.projectcalico.org created customresourcedefinition.apiextensions.k8s.io/networkpolicies.crd.projectcalico.org created customresourcedefinition.apiextensions.k8s.io/networksets.crd.projectcalico.org created clusterrole.rbac.authorization.k8s.io/calico-kube-controllers created clusterrolebinding.rbac.authorization.k8s.io/calico-kube-controllers created clusterrole.rbac.authorization.k8s.io/calico-node created clusterrolebinding.rbac.authorization.k8s.io/calico-node created daemonset.apps/calico-node created serviceaccount/calico-node created deployment.apps/calico-kube-controllers created serviceaccount/calico-kube-controllers created poddisruptionbudget.policy/calico-kube-controllers created
7.4 查看pod运行状态（每秒刷新一次）
[root@master ~]# watch -n 1 kubectl get pod -n kube-system [root@master ~]# kubectl get pod -n kube-system NAME READY STATUS RESTARTS AGE calico-kube-controllers-d8b9b6478-2khtq 1/1 Running 0 110s calico-node-f4t6r 1/1 Running 0 110s calico-node-f6xfz 1/1 Running 0 110s calico-node-mck5r 1/1 Running 0 110s coredns-7f8cbcb969-2ddsl 1/1 Running 0 4d15h coredns-7f8cbcb969-pm5s8 1/1 Running 0 4d15h etcd-master 1/1 Running 1 4d15h kube-apiserver-master 1/1 Running 1 4d15h kube-controller-manager-master 1/1 Running 1 (70s ago) 4d15h kube-proxy-2hzkf 1/1 Running 0 4d15h kube-proxy-grx5m 1/1 Running 0 4d15h kube-proxy-klklc 1/1 Running 0 4d15h kube-scheduler-master 1/1 Running 2 (73s ago) 4d15h
7.5 查看集群状态
[root@master ~]# kubectl get nodes NAME STATUS ROLES AGE VERSION master Ready control-plane 4d15h v1.25.0 node1 Ready <none> 4d15h v1.25.0 node2 Ready <none> 4d15h v1.25.0
八、测试
- 使用k8s启动一个deployment资源
[root@master ~]# vim deploy-nginx.yaml
[root@master ~]# cat deploy-nginx.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
spec:
selector:
matchLabels:
app: nginx
replicas: 3 # 告知 Deployment 运行 3 个与该模板匹配的 Pod
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.14.2
ports:
- containerPort: 80
[root@master ~]# kubectl apply -f deploy-nginx.yaml
deployment.apps/nginx-deployment created
[root@master ~]# kubectl get pod
NAME READY STATUS RESTARTS AGE
nginx-deployment-7fb96c846b-48h24 1/1 Running 0 14s
nginx-deployment-7fb96c846b-ms7c9 1/1 Running 0 14s
nginx-deployment-7fb96c846b-zpsf7 1/1 Running 0 14s
查看所有pod运行状态
[root@master ~]# kubectl get pod -A -o wide NAMESPACE NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES default nginx-deployment-7fb96c846b-48h24 1/1 Running 0 61s 172.16.104.3 node2 <none> <none> default nginx-deployment-7fb96c846b-ms7c9 1/1 Running 0 61s 172.16.166.130 node1 <none> <none> default nginx-deployment-7fb96c846b-zpsf7 1/1 Running 0 61s 172.16.166.131 node1 <none> <none> kube-system calico-kube-controllers-d8b9b6478-2khtq 1/1 Running 0 6m46s 172.16.166.129 node1 <none> <none> kube-system calico-node-f4t6r 1/1 Running 0 6m46s 192.168.1.93 node1 <none> <none> kube-system calico-node-f6xfz 1/1 Running 0 6m46s 192.168.1.92 master <none> <none> kube-system calico-node-mck5r 1/1 Running 0 6m46s 192.168.1.94 node2 <none> <none> kube-system coredns-7f8cbcb969-2ddsl 1/1 Running 0 4d15h 172.16.104.2 node2 <none> <none> kube-system coredns-7f8cbcb969-pm5s8 1/1 Running 0 4d15h 172.16.104.1 node2 <none> <none> kube-system etcd-master 1/1 Running 1 4d15h 192.168.1.92 master <none> <none> kube-system kube-apiserver-master 1/1 Running 1 4d15h 192.168.1.92 master <none> <none> kube-system kube-controller-manager-master 1/1 Running 1 (6m6s ago) 4d15h 192.168.1.92 master <none> <none> kube-system kube-proxy-2hzkf 1/1 Running 0 4d15h 192.168.1.94 node2 <none> <none> kube-system kube-proxy-grx5m 1/1 Running 0 4d15h 192.168.1.92 master <none> <none> kube-system kube-proxy-klklc 1/1 Running 0 4d15h 192.168.1.93 node1 <none> <none> kube-system kube-scheduler-master 1/1 Running 2 (6m9s ago) 4d15h 192.168.1.92 master <none> <none>
标签：k8s,Centos,Kubernetes,containerd,kubelet,Running,master,io,kube From： https://www.cnblogs.com/yangzp/p/16931469.html