k8s的组件和部署方法介绍

这篇文章的知识点包括：kubernetes的组件介绍、kubernetes的核心概念、kubernetes集群部署以及kubernetes的使用，阅读完整文相信大家对kubernetes有了一定的认识。

1、Master组件

●kube-apiserver
Kubernetes API,集群的统一入口，各组件协调者，以RESTful API提供接口服务，所有对象资源的增删改查和监听操作都交给APIServer处理后再提交给Etcd存储。

●kube-controller-manager
处理集群中常规后台任务，一个 资源对应一个控制 器，而ControllerManager就是负责管理这些控制器的。

●kube-scheduler
根据调度算法为新创建的Pod选择一个Node节点，可以任意部署，可以部署在同一个节点上，也可以部署在不同的节点上。

●etcd
分布式键值存储系统。用于保存集群状态数据，比如Pod、Service 等对象信息。

2、Node组件

●kubelet
kubelet是Master在Node节点上的Agent，管理本机运行容器的生命周期，比如创建容器、Pod挂载数据卷、下 载secret、获取容器和节点状态等工作。kubelet将 每个Pod转换成一组容器。

●kube-proxy
在Node节点上实现Pod网络代理，维护网络规则和四层负载均衡工作。

●docker或rocket
容器引擎，运行容器。

工作原理：

1、准备包含应用程序的Deployment的yml文件，然后通过kubectl客户端工具发送给ApiServer。

2、ApiServer接收到客户端的请求并将资源内容存储到数据库(etcd)中。

3、Controller组件(包括scheduler、replication、endpoint)监控资源变化并作出反应。

4、ReplicaSet检查数据库变化，创建期望数量的pod实例。

5、Scheduler再次检查数据库变化，发现尚未被分配到具体执行节点(node)的Pod，然后根据一组相关规则将pod分配到可以运行它们的节点上，并更新数据库，记录pod分配情况。

6、Kubelete监控数据库变化，管理后续pod的生命周期，发现被分配到它所在的节点上运行的那些pod。如果找到新pod，则会在该节点上运行这个新pod。

附：kuberproxy运行在集群各个主机上，管理网络通信，如服务发现、负载均衡。当有数据发送到主机时，将其路由到正确的pod或容器。对于从主机上发出的数据，它可以基于请求地址发现远程服务器，并将数据正确路由，在某些情况下会使用轮循调度算法(Round-robin)将请求发送到集群中的多个实例。

Kubernetes核心概念

1、Pod

●最小部署单元

●一组容器的集合

●一个Pod中的容器共享网络命名空间

●Pod是短暂的

2、Controllers

●ReplicaSet :确保 预期的Pod副本数量

●Deployment:无状态应用 部署

●StatefulSet :有状态应用部署

●DaemonSet:确保所有Node运行同一个Pod

●Job:一次性任务

●Cronjob:定时任务

更高级层次对象，部署和管理Pod

3、Service

●防止Pod失联

●定义一组Pod的访问策略

●Label: 标签，附加到某个资源上，用于关联对象、查询和筛选

●Namespaces :命 名空间，将对象逻辑上隔离

●Annotations :注释

Kubernetes集群部署

1.官方提供的三种部署方式

●minikube

Minikube是一个工具，可以在本地快速运行一个单点的Kubernetes，仅用于尝试Kubernetes或日常开发的用户使用。
部署地址: https://kubernetes.io/docs/setup/minikube/

●kubeadm

Kubeadm也是一个工具，提供kubeadm init和kubeadm join,用于快速部署Kubernetes集群。

部署地址:https://kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm/

●二进制包

推荐，从官方下载发行版的二进制包，手动部署每个组件，组成Kubernetes集群。

下载地址:https://github.com/kubernetes/kubernetes/releases

1. Kubernetes 平台环境规划

3.自签SSL证书

1. Etcd数据库集群部署

                                                       Kubernetes二进制部署
k8s软件包：

链接：https://pan.baidu.com/s/1oN2wkGZ_7parS8sMaaogGw 
提取码：lbjx

k8s部署规划：
master：192.168.35.128      kube-apiserver kube-controller-manager kube-scheduler etcd
node1：192.168.35.195       kubelet kube-proxy docker flannel etcd
node2：192.168.35.138       kubelet kube-proxy docker flannel etcd

master操作：
[root@localhost ~]# mkdir k8s
[root@localhost ~]# cd k8s/
[root@localhost k8s]# ls    //从宿主机拖进来
etcd-cert.sh  etcd.sh
[root@localhost k8s]# mkdir etcd-cert
[root@localhost k8s]# mv etcd-cert.sh etcd-cert
上面 etcd-cert.sh etcd.sh脚本

vim etcd.sh

#!/bin/bash
#example: ./etcd.sh etcd01 192.168.1.10 etcd02=https://192.168.1.11:2380,etcd03=https://192.168.1.12:2380

ETCD_NAME=$1
ETCD_IP=$2
ETCD_CLUSTER=$3

WORK_DIR=/opt/etcd

cat <<EOF >$WORK_DIR/cfg/etcd
#[Member]
ETCD_NAME="${ETCD_NAME}"
ETCD_DATA_DIR="/var/lib/etcd/default.etcd"
ETCD_LISTEN_PEER_URLS="https://${ETCD_IP}:2380"
ETCD_LISTEN_CLIENT_URLS="https://${ETCD_IP}:2379"

#[Clustering]
ETCD_INITIAL_ADVERTISE_PEER_URLS="https://${ETCD_IP}:2380"
ETCD_ADVERTISE_CLIENT_URLS="https://${ETCD_IP}:2379"
ETCD_INITIAL_CLUSTER="etcd01=https://${ETCD_IP}:2380,${ETCD_CLUSTER}"
ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster"
ETCD_INITIAL_CLUSTER_STATE="new"
EOF

cat <<EOF >/usr/lib/systemd/system/etcd.service
[Unit]
Description=Etcd Server
After=network.target
After=network-online.target
Wants=network-online.target

[Service]
Type=notify
EnvironmentFile=${WORK_DIR}/cfg/etcd
ExecStart=${WORK_DIR}/bin/etcd \
--name=\${ETCD_NAME} \
--data-dir=\${ETCD_DATA_DIR} \
--listen-peer-urls=\${ETCD_LISTEN_PEER_URLS} \
--listen-client-urls=\${ETCD_LISTEN_CLIENT_URLS},http://127.0.0.1:2379 \
--advertise-client-urls=\${ETCD_ADVERTISE_CLIENT_URLS} \
--initial-advertise-peer-urls=\${ETCD_INITIAL_ADVERTISE_PEER_URLS} \
--initial-cluster=\${ETCD_INITIAL_CLUSTER} \
--initial-cluster-token=\${ETCD_INITIAL_CLUSTER_TOKEN} \
--initial-cluster-state=new \
--cert-file=${WORK_DIR}/ssl/server.pem \
--key-file=${WORK_DIR}/ssl/server-key.pem \
--peer-cert-file=${WORK_DIR}/ssl/server.pem \
--peer-key-file=${WORK_DIR}/ssl/server-key.pem \
--trusted-ca-file=${WORK_DIR}/ssl/ca.pem \
--peer-trusted-ca-file=${WORK_DIR}/ssl/ca.pem
Restart=on-failure
LimitNOFILE=65536

[Install]
WantedBy=multi-user.target
EOF

systemctl daemon-reload
systemctl enable etcd
systemctl restart etcd

vim etcd-cert.sh

cat > ca-config.json <<EOF
{
  "signing": {
    "default": {
      "expiry": "87600h"
    },
    "profiles": {
      "www": {
         "expiry": "87600h",
         "usages": [
            "signing",
            "key encipherment",
            "server auth",
            "client auth"
        ]
      }
    }
  }
}
EOF

cat > ca-csr.json <<EOF
{
    "CN": "etcd CA",
    "key": {
        "algo": "rsa",
        "size": 2048
    },
    "names": [
        {
            "C": "CN",
            "L": "Beijing",
            "ST": "Beijing"
        }
    ]
}
EOF

cfssl gencert -initca ca-csr.json | cfssljson -bare ca -

#-----------------------

cat > server-csr.json <<EOF
{
    "CN": "etcd",
    "hosts": [
    "10.206.240.188",
    "10.206.240.189",
    "10.206.240.111"
    ],
    "key": {
        "algo": "rsa",
        "size": 2048
    },
    "names": [
        {
            "C": "CN",
            "L": "BeiJing",
            "ST": "BeiJing"
        }
    ]
}
EOF

cfssl gencert -ca=ca.pem -ca-key=ca-key.pem -config=ca-config.json -profile=www server-csr.json | cfssljson -bare server

下载官方包 

[root@localhost k8s]# vim cfssl.sh
curl -L https://pkg.cfssl.org/R1.2/cfssl_linux-amd64 -o /usr/local/bin/cfssl
curl -L https://pkg.cfssl.org/R1.2/cfssljson_linux-amd64 -o /usr/local/bin/cfssljson
curl -L https://pkg.cfssl.org/R1.2/cfssl-certinfo_linux-amd64 -o /usr/local/bin/cfssl-certinfo
chmod +x /usr/local/bin/cfssl /usr/local/bin/cfssljson /usr/local/bin/cfssl-certinfo

[root@localhost k8s]# bash cfssl.sh  //下载cfssl官方包
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  9.8M  100  9.8M    0     0  77052      0  0:02:14  0:02:14 --:--:-- 94447
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 2224k  100 2224k    0     0  66701      0  0:00:34  0:00:34 --:--:-- 71949
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 6440k  100 6440k    0     0  74368      0  0:01:28  0:01:28 --:--:-- 93942

[root@localhost k8s]# ls /usr/local/bin/
cfssl  cfssl-certinfo  cfssljson
//cfssl 生成证书工具、cfssljson通过传入json文件生成证书、cfssl-certinfo查看证书信息
定义证书

[root@localhost k8s]# cd etcd-cert/

//定义ca证书
cat > ca-config.json <<EOF
{
  "signing": {
    "default": {
      "expiry": "87600h"
    },
    "profiles": {
      "www": {
         "expiry": "87600h",
         "usages": [
            "signing",
            "key encipherment",
            "server auth",
            "client auth"     
        ]  
      } 
    }         
  }
}
EOF 

实现证书签名

//实现证书签名
cat > ca-csr.json <<EOF 
{   
    "CN": "etcd CA",
    "key": {
        "algo": "rsa",
        "size": 2048
    },
    "names": [
        {
            "C": "CN",
            "L": "Beijing",
            "ST": "Beijing"
        }
    ]
}
EOF
生产证书，生成ca-key.pem  ca.pem

//生产证书，生成ca-key.pem  ca.pem
cfssl gencert -initca ca-csr.json | cfssljson -bare ca -

2020/01/15 18:15:15 [INFO] generating a new CA key and certificate from CSR
2020/01/15 18:15:15 [INFO] generate received request
2020/01/15 18:15:15 [INFO] received CSR
2020/01/15 18:15:15 [INFO] generating key: rsa-2048
2020/01/15 18:15:15 [INFO] encoded CSR
2020/01/15 18:15:15 [INFO] signed certificate with serial number 661808851940283859099066838380794010566731982441
指定etcd三个节点之间的通信验证

//指定etcd三个节点之间的通信验证
cat > server-csr.json <<EOF
{
    "CN": "etcd",
    "hosts": [
    "192.168.35.128",
    "192.168.35.195",
    "192.168.35.138"
    ],
    "key": {
        "algo": "rsa",
        "size": 2048
    },
    "names": [
        {
            "C": "CN",
            "L": "BeiJing",
            "ST": "BeiJing"
        }
    ]
}
EOF

生成ETCD证书 server-key.pem   server.pem

//生成ETCD证书 server-key.pem   server.pem
cfssl gencert -ca=ca.pem -ca-key=ca-key.pem -config=ca-config.json -profile=www server-csr.json | cfssljson -bare server

www server-csr.json | cfssljson -bare server
2020/01/15 18:24:09 [INFO] generate received request
2020/01/15 18:24:09 [INFO] received CSR
2020/01/15 18:24:09 [INFO] generating key: rsa-2048
2020/01/15 18:24:09 [INFO] encoded CSR
2020/01/15 18:24:09 [INFO] signed certificate with serial number 613252568370198035643630635602034323043189506463
2020/01/15 18:24:09 [WARNING] This certificate lacks a "hosts" field. This makes it unsuitable for
websites. For more information see the Baseline Requirements for the Issuance and Management
of Publicly-Trusted Certificates, v.1.1.6, from the CA/Browser Forum (https://cabforum.org);
specifically, section 10.2.3 ("Information Requirements").
复制软件包到centos7中

[root@localhost etcd-cert]# cd /root/k8s/
[root@localhost k8s]# ls              //直接拉取到目录下
cfssl.sh   etcd.sh                          flannel-v0.10.0-linux-amd64.tar.gz
etcd-cert  etcd-v3.3.10-linux-amd64.tar.gz  kubernetes-server-linux-amd64.tar.gz

解压

[root@localhost k8s]# tar zxvf etcd-v3.3.10-linux-amd64.tar.gz

[root@localhost k8s]# ls etcd-v3.3.10-linux-amd64
Documentation  etcd  etcdctl  README-etcdctl.md  README.md  READMEv2-etcdctl.md

[root@localhost k8s]# mkdir /opt/etcd/{cfg,bin,ssl} -p    //配置文件，命令文件，证书

[root@localhost k8s]# mv etcd-v3.3.10-linux-amd64/etcd etcd-v3.3.10-linux-amd64/etcdctl /opt/etcd/bin/
证书拷贝

//证书拷贝
[root@localhost k8s]# cp etcd-cert/*.pem /opt/etcd/ssl/

//进入卡住状态等待其他节点加入
[root@localhost k8s]# bash etcd.sh etcd01 192.168.35.128 etcd02=https://192.168.35.195:2380,etcd03=https://192.168.35.138:2380

使用另外一个会话打开，会发现etcd进程已经开启

[root@localhost ~]# ps aux | grep etcd
root       4653  0.3  0.6 10523616 12140 ?      Ssl  19:49   0:00 /opt/etcd/bin/etcd --name=etcd01 --data-dir=/var/lib/etcd/default.etcd --listen-peer-urls=https://192.168.35.128:2380 --listen-client-urls=https://192.168.35.128:2379,http://127.0.0.1:2379 --advertise-client-urls=https://192.168.35.128:2379 --initial-advertise-peer-urls=https://192.168.35.128:2380 --initial-cluster=etcd01=https://192.168.35.128:2380,etcd02=https://192.168.35.195:2380,etcd03=https://192.168.35.138:2380 --initial-cluster-token=etcd-cluster --initial-cluster-state=new --cert-file=/opt/etcd/ssl/server.pem --key-file=/opt/etcd/ssl/server-key.pem --peer-cert-file=/opt/etcd/ssl/server.pem --peer-key-file=/opt/etcd/ssl/server-key.pem --trusted-ca-file=/opt/etcd/ssl/ca.pem --peer-trusted-ca-file=/opt/etcd/ssl/ca.pem
root       4719  0.0  0.0 112676   984 pts/2    R+   19:50   0:00 grep --color=auto etcd
关闭防火墙

systemctl stop firewalld.service 
setenforce 0

拷贝证书去其他节点

[root@localhost k8s]# scp -r /opt/etcd/ root@192.168.35.195:/opt/
[root@localhost k8s]# scp -r /opt/etcd/ root@192.168.35.138:/opt
启动脚本拷贝其他节点

[root@localhost k8s]# scp /usr/lib/systemd/system/etcd.service root@192.168.35.195:/usr/lib/systemd/system/
[root@localhost k8s]# scp /usr/lib/systemd/system/etcd.service root@192.168.35.138:/usr/lib/systemd/system/
在node01节点修改
[root@localhost ~]# vim /opt/etcd/cfg/etcd

#[Member]
ETCD_NAME="etcd02"
ETCD_DATA_DIR="/var/lib/etcd/default.etcd"
ETCD_LISTEN_PEER_URLS="https://192.168.35.195:2380"
ETCD_LISTEN_CLIENT_URLS="https://192.168.35.195:2379"

#[Clustering]
ETCD_INITIAL_ADVERTISE_PEER_URLS="https://192.168.35.195:2380"
ETCD_ADVERTISE_CLIENT_URLS="https://192.168.35.195:2379"
ETCD_INITIAL_CLUSTER="etcd01=https://192.168.35.128:2380,etcd02=https://192.168.35.195:2380,etcd03=https://192.168.35.138:2380"
ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster"
ETCD_INITIAL_CLUSTER_STATE="new"

在node02节点修改
[root@localhost ~]# vim /opt/etcd/cfg/etcd

#[Member]
ETCD_NAME="etcd03"
ETCD_DATA_DIR="/var/lib/etcd/default.etcd"
ETCD_LISTEN_PEER_URLS="https://192.168.35.138:2380"
ETCD_LISTEN_CLIENT_URLS="https://192.168.35.138:2379"

#[Clustering]
ETCD_INITIAL_ADVERTISE_PEER_URLS="https://192.168.35.138:2380"
ETCD_ADVERTISE_CLIENT_URLS="https://192.168.35.138:2379"
ETCD_INITIAL_CLUSTER="etcd01=https://192.168.35.128:2380,etcd02=https://192.168.35.195:2380,etcd03=https://192.168.35.138:2380"
ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster"
ETCD_INITIAL_CLUSTER_STATE="new"

先在master上开启服务
[root@localhost system]# cd /root/k8s/
[root@localhost k8s]# bash etcd.sh etcd01 192.168.35.128 etcd02=https://192.168.35.195:2380,etcd03=https://192.168.35.138:2380
在node1和node2上开启服务
[root@localhost ~]# systemctl start etcd
[root@localhost ~]# systemctl status etcd
再去master查看，会发现同步成功
[root@localhost k8s]# bash etcd.sh etcd01 192.168.35.128 etcd02=https://192.168.35.195:2380,etcd03=https://192.168.35.138:2380

检查群集状态
[root@localhost k8s]# cd etcd-cert/
[root@localhost etcd-cert]# /opt/etcd/bin/etcdctl --ca-file=ca.pem --cert-file=server.pem --key-file=server-key.pem --endpoints="https://192.168.35.128:2379,https://192.168.35.195:2379,https://192.168.35.138:2379" cluster-health
member 12a96220ac829a49 is healthy: got healthy result from https://192.168.35.195:2379
member 76797989afd0ecba is healthy: got healthy result from https://192.168.35.128:2379
member ff469df2baaba1da is healthy: got healthy result from https://192.168.35.138:2379
cluster is healthy

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