企业kubernetes平台应用该从哪里开始？丨企业为什么会选择K8s发布应用丨

企业kubernetes平台应用该从哪里开始？

一、企业为什么选择Kubernetes发布应用？

• 基础设施与业务的解耦
  • 早期开发懂运维，运维懂开发
• 基础设施自身的标准化
  • 例如镜像格式标准

二、Kubernetes架构模式

• 架构分类一：单体架构、分布式架构、微服务架构、超微服务架构
• 架构分类二：有中心节点架构、无中心节点架构
  • 有中心节点 例如hadoop中的hdfs文件系统
  • 无中心节点架构 例如分布式存储 GlusterFS
• kubernetes属于有中心节点的架构

三、从使用者角度了解Kubernetes集群部署方式

• kubeadm
• kubekey
• kubease
• kubroad
• sealos
• rancher
• minikube
• 二进制

四、Kubeadm部署Kubernetes集群

4.1 主机操作系统说明

序号	操作系统及版本	备注
1	CentOS7u9

4.2 主机硬件配置说明

需求	CPU	内存	硬盘	角色	主机名
值	4C	8G	100GB	master	master01
值	4C	8G	100GB	worker(node)	worker01
值	4C	8G	100GB	worker(node)	worker02

4.3 主机配置

4.3.1 主机名配置

由于本次使用3台主机完成kubernetes集群部署，其中1台为master节点,名称为master01;其中2台为worker节点，名称分别为：worker01及worker02

master节点,名称为master1
# hostnamectl set-hostname master01

worker1节点,名称为worker1
# hostnamectl set-hostname worker01

worker2节点,名称为worker2
# hostnamectl set-hostname worker02

4.3.2 主机IP地址配置

master节点IP地址为：192.168.10.11/24
# vim /etc/sysconfig/network-scripts/ifcfg-ens33
TYPE="Ethernet"
PROXY_METHOD="none"
BROWSER_ONLY="no"
BOOTPROTO="none"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
IPV6_ADDR_GEN_MODE="stable-privacy"
NAME="ens33"
DEVICE="ens33"
ONBOOT="yes"
IPADDR="192.168.10.11"
PREFIX="24"
GATEWAY="192.168.10.2"
DNS1="119.29.29.29"

worker1节点IP地址为：192.168.10.12/24
# vim /etc/sysconfig/network-scripts/ifcfg-ens33
TYPE="Ethernet"
PROXY_METHOD="none"
BROWSER_ONLY="no"
BOOTPROTO="none"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
IPV6_ADDR_GEN_MODE="stable-privacy"
NAME="ens33"
DEVICE="ens33"
ONBOOT="yes"
IPADDR="192.168.10.12"
PREFIX="24"
GATEWAY="192.168.10.2"
DNS1="119.29.29.29"

worker2节点IP地址为：192.168.10.13/24
# vim /etc/sysconfig/network-scripts/ifcfg-ens33
TYPE="Ethernet"
PROXY_METHOD="none"
BROWSER_ONLY="no"
BOOTPROTO="none"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
IPV6_ADDR_GEN_MODE="stable-privacy"
NAME="ens33"
DEVICE="ens33"
ONBOOT="yes"
IPADDR="192.168.10.13"
PREFIX="24"
GATEWAY="192.168.10.2"
DNS1="119.29.29.29"

4.3.3 主机名与IP地址解析

所有集群主机均需要进行配置。

# cat /etc/hosts
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.10.11 master01
192.168.10.12 worker01
192.168.10.13 worker02

4.3.4 防火墙配置

所有主机均需要操作。

关闭现有防火墙firewalld
# systemctl disable firewalld
# systemctl stop firewalld
# firewall-cmd --state
not running

4.3.5 SELINUX配置

所有主机均需要操作。修改SELinux配置需要重启操作系统。

# sed -ri 's/SELINUX=enforcing/SELINUX=disabled/' /etc/selinux/config

4.3.6 时间同步配置

所有主机均需要操作。最小化安装系统需要安装ntpdate软件。

# crontab -l
0 */1 * * * /usr/sbin/ntpdate time1.aliyun.com

4.3.7 升级操作系统内核

所有主机均需要操作。

导入elrepo gpg key
# rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org

安装elrepo YUM源仓库
# yum -y install https://www.elrepo.org/elrepo-release-7.0-4.el7.elrepo.noarch.rpm

安装kernel-ml版本，ml为长期稳定版本，lt为长期维护版本
# yum --enablerepo="elrepo-kernel" -y install kernel-ml.x86_64

设置grub2默认引导为0
# grub2-set-default 0

重新生成grub2引导文件
# grub2-mkconfig -o /boot/grub2/grub.cfg

更新后，需要重启，使用升级的内核生效。
# reboot

重启后，需要验证内核是否为更新对应的版本
# uname -r

4.3.8 配置内核转发及网桥过滤

所有主机均需要操作。

添加网桥过滤及内核转发配置文件
# cat /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
vm.swappiness = 0

加载br_netfilter模块
# modprobe br_netfilter

查看是否加载
# lsmod | grep br_netfilter
br_netfilter           22256  0
bridge                151336  1 br_netfilter

加载网桥过滤及内核转发配置文件
# sysctl -p /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
vm.swappiness = 0

4.3.9 安装ipset及ipvsadm

所有主机均需要操作。主要用于实现service转发。

安装ipset及ipvsadm
# yum -y install ipset ipvsadm

配置ipvsadm模块加载方式
添加需要加载的模块
# 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
EOF

授权、运行、检查是否加载
# chmod 755 /etc/sysconfig/modules/ipvs.modules && bash /etc/sysconfig/modules/ipvs.modules && lsmod | grep -e ip_vs -e nf_conntrack

4.3.10 关闭SWAP分区

修改完成后需要重启操作系统，如不重启，可临时关闭，命令为swapoff -a

永远关闭swap分区，需要重启操作系统
# cat /etc/fstab
......

# /dev/mapper/centos-swap swap                    swap    defaults        0 0

在上一行中行首添加#

4.4 Docker准备

所有集群主机均需操作。

4.4.1 获取YUM源

使用阿里云开源软件镜像站。

# wget https://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo -O /etc/yum.repos.d/docker-ce.repo

4.4.2 查看可安装版本

# yum list docker-ce.x86_64 --showduplicates | sort -r

4.4.3 安装指定版本并设置启动及开机自启动

# yum -y install --setopt=obsoletes=0 docker-ce-20.10.9-3.el7

# systemctl enable docker ; systemctl start docker

4.4.4 修改cgroup方式

在/etc/docker/daemon.json添加如下内容

# cat /etc/docker/daemon.json
{
    
    
        "exec-opts": ["native.cgroupdriver=systemd"]
}

4.4.5 重启docker

# systemctl restart docker

4.5 集群软件及版本说明

	kubeadm	kubelet	kubectl
版本	1.21.0	1.21.0	1.21.0
安装位置	集群所有主机	集群所有主机	集群所有主机
作用	初始化集群、管理集群等	用于接收api-server指令，对pod生命周期进行管理	集群应用命令行管理工具

4.6 kubernetes YUM源准备

4.6.1 谷歌YUM源

[kubernetes]
name=Kubernetes
baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
repo_gpgcheck=0
gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg
        https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg

4.6.2 阿里云YUM源

[kubernetes]
name=Kubernetes
baseurl=https://mirrors.aliyun.com/kubernetes/yum/repos/kubernetes-el7-x86_64/
enabled=1
gpgcheck=0
repo_gpgcheck=0
gpgkey=https://mirrors.aliyun.com/kubernetes/yum/doc/yum-key.gpg https://mirrors.aliyun.com/kubernetes/yum/doc/rpm-package-key.gpg

4.7 集群软件安装

查看指定版本
# yum list kubeadm.x86_64 --showduplicates | sort -r
# yum list kubelet.x86_64 --showduplicates | sort -r
# yum list kubectl.x86_64 --showduplicates | sort -r

安装指定版本
# yum -y install --setopt=obsoletes=0 kubeadm-1.21.0-0  kubelet-1.21.0-0 kubectl-1.21.0-0

4.8 配置kubelet

为了实现docker使用的cgroupdriver与kubelet使用的cgroup的一致性，建议修改如下文件内容。

# vim /etc/sysconfig/kubelet
KUBELET_EXTRA_ARGS="--cgroup-driver=systemd"

设置kubelet为开机自启动即可，由于没有生成配置文件，集群初始化后自动启动
# systemctl enable kubelet

4.9 集群镜像准备

可使用VPN实现下载。

# kubeadm config images list --kubernetes-version=v1.21.0
k8s.gcr.io/kube-apiserver:v1.21.0
k8s.gcr.io/kube-controller-manager:v1.21.0
k8s.gcr.io/kube-scheduler:v1.21.0
k8s.gcr.io/kube-proxy:v1.21.0
k8s.gcr.io/pause:3.4.1
k8s.gcr.io/etcd:3.4.13-0
k8s.gcr.io/coredns/coredns:v1.8.0

# cat image_download.sh
#!/bin/bash
images_list='
k8s.gcr.io/kube-apiserver:v1.21.0
k8s.gcr.io/kube-controller-manager:v1.21.0
k8s.gcr.io/kube-scheduler:v1.21.0
k8s.gcr.io/kube-proxy:v1.21.0
k8s.gcr.io/pause:3.4.1
k8s.gcr.io/etcd:3.4.13-0
k8s.gcr.io/coredns/coredns:v1.8.0'

for i in $images_list
do
        docker pull $i
done

docker save -o k8s-1-21-0.tar $images_list

4.10 集群初始化

[root@master01 ~]# kubeadm init --kubernetes-version=v1.21.0 --pod-network-cidr=10.244.0.0/16 --apiserver-advertise-address=192.168.10.11

输出内容，一定保留，便于后继操作使用。
[init] Using Kubernetes version: v1.21.0
[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
[certs] apiserver serving cert is signed for DNS names [kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local master01] and IPs [10.96.0.1 192.168.10.11]
[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 master01] and IPs [192.168.10.11 127.0.0.1 ::1]
[certs] Generating "etcd/peer" certificate and key
[certs] etcd/peer serving cert is signed for DNS names [localhost master01] and IPs [192.168.10.11 127.0.0.1 ::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
[kubelet-check] Initial timeout of 40s passed.
[apiclient] All control plane components are healthy after 57.503834 seconds
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config-1.21" 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 master01 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 master01 as control-plane by adding the taints [node-role.kubernetes.io/master:NoSchedule]
[bootstrap-token] Using token: 9kz5id.pp5rhvzahj51lb5q
[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 192.168.10.11:6443 --token 9kz5id.pp5rhvzahj51lb5q \
        --discovery-token-ca-cert-hash sha256:86f9c4471b6ef08090ecffadc798040fe5d8ef5975afe527e65d2f0aedf66493

4.11 集群应用客户端管理集群文件准备

[root@master1 ~]# mkdir -p $HOME/.kube
[root@master1 ~]# cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
[root@master1 ~]# chown $(id -u):$(id -g) $HOME/.kube/config
[root@master1 ~]# ls /root/.kube/
config

# export KUBECONFIG=/etc/kubernetes/admin.conf

4.12 集群网络准备

使用calico部署集群网络

安装参考网址：https://projectcalico.docs.tigera.io/about/about-calico

4.12.1 calico安装

下载operator资源清单文件
# wget https://docs.projectcalico.org/manifests/tigera-operator.yaml

应用资源清单文件，创建operator
# kubectl apply -f tigera-operator.yaml

通过自定义资源方式安装
# wget https://docs.projectcalico.org/manifests/custom-resources.yaml

修改文件第13行，修改为使用kubeadm init ----pod-network-cidr对应的IP地址段
# vim custom-resources.yaml
......
 11     ipPools:
 12     - blockSize: 26
 13       cidr: 10.244.0.0/16 
 14       encapsulation: VXLANCrossSubnet
......

应用资源清单文件
# kubectl apply -f custom-resources.yaml

监视calico-sysem命名空间中pod运行情况
# watch kubectl get pods -n calico-system

Wait until each pod has the STATUS of Running.

删除 master 上的 taint
# kubectl taint nodes --all node-role.kubernetes.io/master-

已经全部运行
# kubectl get pods -n calico-system
NAME                                      READY   STATUS    RESTARTS   AGE
calico-kube-controllers-666bb9949-dzp68   1/1     Running   0          11m
calico-node-jhcf4                         1/1     Running   4          11m
calico-typha-68b96d8d9c-7qfq7             1/1     Running   2          11m

查看kube-system命名空间中coredns状态，处于Running状态表明联网成功。
# kubectl get pods -n kube-system
NAME                               READY   STATUS    RESTARTS   AGE
coredns-558bd4d5db-4jbdv           1/1     Running   0          113m
coredns-558bd4d5db-pw5x5           1/1     Running   0          113m
etcd-master01                      1/1     Running   0          113m
kube-apiserver-master01            1/1     Running   0          113m
kube-controller-manager-master01   1/1     Running   4          113m
kube-proxy-kbx4z                   1/1     Running   0          113m
kube-scheduler-master01            1/1     Running   3          113m

4.12.2 calico客户端安装

下载二进制文件
# curl -L https://github.com/projectcalico/calico/releases/download/v3.21.4/calicoctl-linux-amd64 -o calicoctl

安装calicoctl
# mv calicoctl /usr/bin/

为calicoctl添加可执行权限
# chmod +x /usr/bin/calicoctl

查看添加权限后文件
# ls /usr/bin/calicoctl
/usr/bin/calicoctl

查看calicoctl版本
# calicoctl  version
Client Version:    v3.21.4
Git commit:        220d04c94
Cluster Version:   v3.21.4
Cluster Type:      typha,kdd,k8s,operator,bgp,kubeadm

通过~/.kube/config连接kubernetes集群，查看已运行节点
# DATASTORE_TYPE=kubernetes KUBECONFIG=~/.kube/config calicoctl get nodes
NAME
master01

4.13 集群工作节点添加

因容器镜像下载较慢，可能会导致报错，主要错误为没有准备好cni（集群网络插件），如有网络，请耐心等待即可。

[root@worker01 ]# kubeadm join 192.168.10.11:6443 --token 9kz5id.pp5rhvzahj51lb5q \
        --discovery-token-ca-cert-hash sha256:86f9c4471b6ef08090ecffadc798040fe5d8ef5975afe527e65d2f0aedf66493

[root@worker02 ~]# kubeadm join 192.168.10.11:6443 --token 9kz5id.pp5rhvzahj51lb5q \
        --discovery-token-ca-cert-hash sha256:86f9c4471b6ef08090ecffadc798040fe5d8ef5975afe527e65d2f0aedf66493

在master节点上操作，查看网络节点是否添加
# DATASTORE_TYPE=kubernetes KUBECONFIG=~/.kube/config calicoctl get nodes
NAME
master01
worker01
worker02

4.14 验证集群可用性

查看所有的节点
[root@master01 ~]# kubectl get nodes
NAME       STATUS   ROLES                  AGE    VERSION
master01   Ready    control-plane,master   169m   v1.21.0
worker01   Ready    <none>                 28m    v1.21.0
worker02   Ready    <none>                 28m    v1.21.0

查看集群健康情况,理想状态
[root@master01 ~]# kubectl get cs
NAME                 STATUS    MESSAGE             ERROR
controller-manager   Healthy   ok
scheduler            Healthy   ok
etcd-0               Healthy   {
    
    "health":"true"}

真实情况
# kubectl get cs
Warning: v1 ComponentStatus is deprecated in v1.19+
NAME                 STATUS      MESSAGE                                                                                       ERROR
scheduler            Unhealthy   Get "http://127.0.0.1:10251/healthz": dial tcp 127.0.0.1:10251: connect: connection refused
controller-manager   Unhealthy   Get "http://127.0.0.1:10252/healthz": dial tcp 127.0.0.1:10252: connect: connection refused
etcd-0               Healthy     {
    
    "health":"true"}

查看kubernetes集群pod运行情况
[root@master01 ~]# kubectl get pods -n kube-system
NAME                               READY   STATUS    RESTARTS   AGE
coredns-558bd4d5db-4jbdv           1/1     Running   1          169m
coredns-558bd4d5db-pw5x5           1/1     Running   1          169m
etcd-master01                      1/1     Running   1          170m
kube-apiserver-master01            1/1     Running   1          170m
kube-controller-manager-master01   1/1     Running   14         170m
kube-proxy-kbx4z                   1/1     Running   1          169m
kube-proxy-rgtr8                   1/1     Running   0          29m
kube-proxy-sq9xv                   1/1     Running   0          29m
kube-scheduler-master01            1/1     Running   11         170m

再次查看calico-system命名空间中pod运行情况。
[root@master01 ~]# kubectl get pods -n calico-system
NAME                                      READY   STATUS    RESTARTS   AGE
calico-kube-controllers-666bb9949-dzp68   1/1     Running   3          70m
calico-node-jhcf4                         1/1     Running   15         70m
calico-node-jxq9p                         1/1     Running   0          30m
calico-node-kf78q                         1/1     Running   0          30m
calico-typha-68b96d8d9c-7qfq7             1/1     Running   13         70m
calico-typha-68b96d8d9c-wz2zj             1/1     Running   0          20m