2018-05-22 Linux Learning

18.6 Load Balancing Cluster introduction

主流开源软件LVS、keepalived、haproxy、nginx等其中LVS属于4层（网络OSI 7层模型），nginx属于7层，haproxy既可以认为是4层，也可以当做7层使用keepalived的负载均衡功能其实就是lvslvs这种4层的负载均衡是可以分发除80外的其他端口通信的，比如MySQL的，而nginx仅仅支持http，https，mail，haproxy也支持MySQL这种相比较来说，LVS这种4层的更稳定，能承受更多的请求，而nginx这种7层的更加灵活，能实现更多的个性化需求

18.7 LVS Introduction

LVS Introduction

LVS是由国人章文嵩开发流行度不亚于apache的httpd，基于TCP/IP做的路由和转发，稳定性和效率很高LVS最新版本基于Linux内核2.6，有好多年不更新了LVS有三种常见的模式：NAT、DR、IP TunnelLVS架构中有一个核心角色叫做分发器（Load balance），它用来分发用户的请求，还有诸多处理用户请求的服务器（Real Server，简称rs）

LVS NAT Mode

这种模式借助iptables的nat表来实现用户的请求到分发器后，通过预设的iptables规则，把请求的数据包转发到后端的rs上去rs需要设定网关为分发器的内网ip用户请求的数据包和返回给用户的数据包全部经过分发器，所以分发器成为瓶颈在nat模式中，只需要分发器有公网ip即可，所以比较节省公网ip资源

LVS IP tunnel mode

这种模式，需要有一个公共的IP配置在分发器和所有rs上，我们把它叫做vip客户端请求的目标IP为vip，分发器接收到请求数据包后，会对数据包做一个加工，会把目标IP改为rs的IP，这样数据包就到了rs上rs接收数据包后，会还原原始数据包，这样目标IP为vip，因为所有rs上配置了这个vip，所以它会认为是它自己

LVS Dr Mode

这种模式，也需要有一个公共的IP配置在分发器和所有rs上，也就是vip和IP Tunnel不同的是，它会把数据包的MAC地址修改为rs的MAC地址rs接收数据包后，会还原原始数据包，这样目标IP为vip，因为所有rs上配置了这个vip，所以它会认为是它自己

Scheduling algorithm for 18.8 LVs

轮询 Round-Robin  rr加权轮询 Weight Round-Robin wrr最小连接 Least-Connection lc加权最小连接 Weight Least-Connection wlc基于局部性的最小连接 Locality-Based Least Connections lblc带复制的基于局部性最小连接 Locality-Based Least Connections with Replication  lblcr目标地址散列调度 Destination Hashing dh源地址散列调度 Source Hashing  sh

18.9-10 LVS NAT Mode construction

Nat Mode Setup – Prep work

三台机器分发器，也叫调度器（简写为dir）内网：133.130，外网：147.144（vmware仅主机模式）rs1内网：133.132rs2内网：133.133三台机器分发器，也叫调度器（简写为dir）内网：133.130，外网：142.147（vmware仅主机模式）rs1内网：133.132，设置网关为133.130rs2内网：133.133，设置网关为133.130三台机器上都执行执行 systemctl stop firewalld; systemc disable firewalldsystemctl start  

Nat Mode Setup

在dir上安装ipvsadmyum install -y ipvsdam在dir上编写脚本，vim /usr/local/sbin/lvs_nat.sh//内容如下

#! /bin/bash

Turn on routing forwarding on the director server

Echo 1 >/proc/sys/net/ipv4/ip_forward

Turn off redirection of ICMP

echo 0 >/proc/sys/net/ipv4/conf/all/send_redirects
echo 0 >/proc/sys/net/ipv4/conf/default/send_redirects

Note the name of the network card, Amin Two network cards are ENS33 and ENS37

echo 0 >/proc/sys/net/ipv4/conf/ens33/send_redirects
echo 0 >/proc/sys/net/ipv4/conf/ens37/send_redirects

Director Set NAT Firewall

Iptables-t nat-f
Iptables-t Nat-x
Iptables-t nat-a postrouting-s 192.168.133.0/24-j Masquerade

Director Setup Ipvsadm

Ipvsadm= '/usr/sbin/ipvsadm '
$IPVSADM-C
$IPVSADM-A-T 192.168.147.144:80-s wlc-p 3
$IPVSADM-T 192.168.147.144:80-r 192.168.133.132:80-m-W 1
$IPVSADM-T 192.168.147.144:80-r 192.168.133.133:80-m-W 1

Nat Mode effect test

两台rs上都安装nginx设置两台rs的主页，做一个区分，也就是说直接curl两台rs的ip时，得到不同的结果浏览器里访问192.168.142.147，多访问几次看结果差异

Operation Process

Distributor configuration, network adapter set to host mode only

[[email protected] ~]# vim /etc/sysconfig/network-scripts/ifcfg-ens37TYPE=EthernetPROXY_METHOD=noneBROWSER_ONLY=noBOOTPROTO=staticDEFROUTE=yesIPV4_FAILURE_FATAL=noIPV6INIT=yesIPV6_AUTOCONF=yesIPV6_DEFROUTE=yesIPV6_FAILURE_FATAL=noIPV6_ADDR_GEN_MODE=stable-privacyNAME=ens37UUID=DEVICE=ens37ONBOOT=yesIPADDR=172.16.166.130PREFIX=24ZONE=在电脑上可以ping通  172.16.166.130[[email protected] ~]# systemctl stop firewalld

Three Linux machines are
Setenforce 0;getenforce
Systemctl Stop Firewalld

Modify the IP of the gateway as a Distributor to form the intranet

[[email protected] ~]# vim /etc/sysconfig/network-scripts/ifcfg-ens33IPADDR=192.168.106.165NETMASK=255.255.255.0GATEWAY=192.168.106.160DNS1=119.29.29.29[[email protected] ~]# systemctl restart network[[email protected] ~]# vim /etc/sysconfig/network-scripts/ifcfg-ens33IPADDR=192.168.106.166NETMASK=255.255.255.0GATEWAY=192.168.106.160DNS1=119.29.29.29[[email protected] ~]# systemctl restart network

Distributor installation Configuration

[email protected] ~]# Yum install-y ipvsadm

[Email protected] ~]# vim/usr/local/sbin/lvs_nat.sh
#! /bin/bash

Turn on routing forwarding on the director server

Echo 1 >/proc/sys/net/ipv4/ip_forward

Turn off redirection of ICMP

echo 0 >/proc/sys/net/ipv4/conf/all/send_redirects
echo 0 >/proc/sys/net/ipv4/conf/default/send_redirects

Note the name of the network card, Amin Two network cards are ENS33 and ENS37

echo 0 >/proc/sys/net/ipv4/conf/ens33/send_redirects
echo 0 >/proc/sys/net/ipv4/conf/ens37/send_redirects

Director Set NAT Firewall

Iptables-t nat-f
Iptables-t Nat-x
Iptables-t nat-a postrouting-s 192.168.106.0/24-j Masquerade

Director Setup Ipvsadm

Ipvsadm= '/usr/sbin/ipvsadm '
$IPVSADM-C
$IPVSADM-A-T 172.16.166.130:80-s wlc-p 3
$IPVSADM-T 172.16.166.130:80-r 192.168.106.165:80-m-W 1
$IPVSADM-T 172.16.166.130:80-r 192.168.106.166:80-m-W 1

[[email protected] ~]# sh /usr/local/sbin/lvs_nat.sh

RS Host Start Nginx

[[email protected] ~]# netstat-lnptactive Internet connections (only servers) Proto recv-q send-q Local Address               Foreign Address State Pid/program name TCP 0 0 0.0.0.0:111 0.0.0.0:* LISTEN 1/systemd TCP 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 946       /sshd TCP 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 1185/master tcp6                   0 0::: 111:::* LISTEN 1/systemd tcp6 0 0::: 22                    :::* LISTEN 946/sshd tcp6 0 0:: 1:25:::* LISTEN 1185/master [[email protected] ~]# systemctl start nginx[[email protected ] ~]# vi/usr/share/nginx/html/index.htmlaminglinux02[[email protected] ~]# Curl Localhostaminglinux02[[email  protected] ~]# vim/usr/shAre/nginx/html/index.htmlaminglinux03[[email protected] ~]# Curl localhostaminglinux03[[email protected ] ~]# ipvsadm-lnip Virtual Server version 1.2.1 (size=4096) Prot localaddress:port Scheduler Flags--Remoteaddress:po           RT Forward Weight activeconn inactconntcp 172.16.166.130:80 WLC Persistent 3-192.168.106.165:80 MASQ 1 0 3-192.168.106.166:80 masq 1 0 0 [[email prote CTED] ~]# vim/usr/local/sbin/lvs_nat.sh$ipvsadm-a-T 172.16.166.130:80-s wlc-p 3 changed to $ipvsadm-a-T 172.16.166.130:80-s Rr

Test access

[[email protected] ~]# curl 172.16.166.130aminglinux03[[email protected] ~]# curl 172.16.166.130aminglinux02[[email protected] ~]# curl 172.16.166.130aminglinux03[[email protected] ~]# curl 172.16.166.130aminglinux02

2018-05-22 Linux Learning