负载均衡集群搭建指南
一、引言
随着互联网技术的迅猛发展,网站的访问量和数据流量呈爆炸性增长,单台服务器无论性能多么强大,也无法单独应对如此巨大的压力,为解决这一问题,负载均衡集群应运而生,通过将多台服务器组合成一个集群系统,负载均衡技术能够将用户请求分配到不同的服务器上,从而提升整体性能和可靠性,本文将详细介绍负载均衡集群的搭建过程,重点讲述使用Nginx和LVS(Linux Virtual Server)的具体步骤和方法。
二、负载均衡集群的基本概念
什么是负载均衡?
负载均衡,英文名称为Load Balance,其含义就是指将负载(工作任务)进行平衡、分摊到多个操作单元上进行运行,例如FTP服务器、Web服务器、企业核心应用服务器和其他主要任务服务器等,从而协同完成工作任务。
为什么需要负载均衡?
在互联网的高并发访问场景下,单台服务器很难独立承担所有请求的压力,通过引入负载均衡技术,可以将请求分摊到多台服务器上,提高系统的处理能力和可靠性,避免单点故障。
负载均衡的类型
DNS负载均衡:基于域名系统的流量分配方式,但存在缓存和调度精度问题。
硬件负载均衡:使用专用设备进行流量分配,成本高但性能强。
软件负载均衡:通过软件算法实现流量分配,常见有Nginx、LVS等。
三、Nginx负载均衡集群搭建
准备工作
1.1下载Nginx
从Nginx官网(http://nginx.org/en/download.html)下载最新版本的Nginx,本文以1.24.0版本为例。
1.2建立工作目录
解压下载的Nginx文件,并建立相应的工作目录:
unzip nginx-1.24.0.zip cd nginx-1.24.0 mkdir master slave1 slave2
master
作为主节点负责代理分发请求,slave1
和slave2
作为从节点提供应用服务。
配置从机
2.1修改默认主页
为了验证配置效果,修改从机的默认主页:
进入slave1的html目录,编辑index.html cd slave1/html echo "I am server: slave-1" > index.html 同理修改slave2的index.html cd ../slave2/html echo "I am server: slave-2" > index.html
2.2修改nginx.conf配置文件
进入从机的conf目录,编辑nginx.conf文件:
进入slave1的conf目录 cd ../slave1/conf cp nginx.conf nginx.conf.orig # 备份原始配置文件 编辑nginx.conf,修改侦听端口 sed -i 's/listen 80;/listen 8081;/' nginx.conf
同样方法修改slave2的nginx.conf文件,侦听端口改为8082。
配置主机
3.1编辑nginx.conf文件
进入主节点的conf目录,编辑nginx.conf文件:
进入master的conf目录 cd ../master/conf cp nginx.conf nginx.conf.orig # 备份原始配置文件 编辑nginx.conf,添加upstream和server配置 { upstream backend { server 127.0.0.1:8081; server 127.0.0.1:8082; } server { listen 80; location / { proxy_pass http://backend; } } }
配置指定了两个后端服务器(slave1和slave2),并将请求轮询分配给它们。
验证效果
启动所有Nginx服务:
启动从机 cd ../slave1 && nginx -g "daemon off; start" & cd ../slave2 && nginx -g "daemon off; start" & 启动主机 cd ../master && nginx -g "daemon off; start"
打开浏览器,访问http://localhost
,刷新页面,观察是否轮流显示I am server: slave-1
和I am server: slave-2
,如果是,则说明负载均衡配置成功。
四、LVS负载均衡集群搭建
LVS介绍
LVS(Linux Virtual Server)是一个高性能、高可用性的负载均衡解决方案,适用于大规模网络环境和复杂的应用场景,LVS支持多种负载均衡模式,如NAT、DR、TUN等。
LVS的优势
高性能:运行在Linux内核空间,能够提供高效的网络数据包处理能力。
高可用性:与Keepalived等高可用软件结合使用,实现故障转移和高可用性。
可扩展性:支持数千个并发连接,适合大型网络环境。
灵活性:支持多种负载均衡算法,可根据需求选择最适合的算法。
LVS的组成
Director Server:调度器,负责接收客户端请求并将其分配给Real Server。
Real Server:真实服务器,实际处理客户端请求的应用服务器。
VIP:虚拟IP地址,客户端通过该地址访问整个集群。
RIP:真实IP地址,集群节点上使用的IP地址。
DIP:Director连接到Real Server的IP地址。
CIP:客户端IP地址。
LVS的工作模式
4.1 NAT模式
在NAT模式下,Director Server作为网关设备,通过修改数据包的源或目的IP地址来实现负载均衡,这种模式的安全性较好,因为Real Server不直接暴露在公网上。
4.2 DR模式
在DR模式下,Director Server仅修改数据包的目的MAC地址,将其路由到Real Server,这要求Director Server和Real Server在同一网段内。
4.3 TUN模式
在TUN模式下,Director Server通过IP隧道将流量转发到Real Server,这种方式适合Real Server分布在不同地理位置的场景。
LVS NAT模式搭建示例
5.1环境准备
假设有以下三台服务器:
Director Server:192.168.59.130
Real Server 1:192.168.59.132
Real Server 2:192.168.59.133
5.2安装ipvsadm工具
在Director Server上安装ipvsadm工具:
yum install -y ipvsadm
检查ipvs模块是否加载:
lsmod | grep ip_vs
如果未加载,手动加载:
modprobe -ip_vs modprobe -ip_vs_rr modprobe -ip_vs_wrr modprobe -ip_vs_sh
5.3配置LVS
添加VIP和Real Server配置:
ipvsadm -A -t 192.168.59.130:80 -s rr ipvsadm -a -t 192.168.59.130:80 -r 192.168.59.132:80 -m -w 100 ipvsadm -a -t 192.168.59.130:80 -r 192.168.59.133:80 -m -w 100
命令表示在VIP为192.168.59.130的80端口上启用轮询(rr)负载均衡策略,并将请求分配到两个Real Server的80端口上,权重均为100。
5.4验证配置
查看LVS配置信息:
ipvsadm -L -n
输出应显示类似如下信息:
TCP Listener on IPv4 address 192.168.59.130 port 80, type NAT multicast weight=0 tcpfinrst=no inact=30s ogTCP Conn Table on IPv4 address 192.168.59.130 port 80 type NAT: realserver[192.168.59.132:80], weight=100, status=> Activeconns=0 inact=0 min_conn=0 max_conn=0 -> forwarding to 192.168.59.132:80 local if=ens33 local port=80 protocol=tcp physicalif=ens33 physicalport=80 proxied=0 proxiedto=0 lastcnn=0 nowcnn=0 bytesin=0 bytesout=0 packetsin=0 packetsout=0 pps_limit=0 cps_limit=0 lapint=5000 congestion=no retran=yes fastreuse=no freeqlen=0 qlen=0 qdisc=0 qdrops=0 opackets=0 mcast_pkts=0 mbytes=0 mjblk=0 mlast=MASTER,MASTQUEUE qlen=0 qdisc=0 qstate=RUNNING qlimit=0 qlimsc=256 qlimtc=256 qtime=0 qblkc=0 qblktc=256 qblktime=0 backlog=50 maxqlen=4000 tcpfinrst=no inact=30s first_sched=yes last_sched=no healthy=1 weight=100 state=> IN_SERVICE protocol=tcp service=80 laweight=100 persistent=no ind=0 flags=-> scheduled <= none global_service=true enable_banned=no ban_timeout=300 ban_threshold=5 redirect_all_peers=no redirect_local_peer=no verify_nodelay=no canary=no canary_local=no canary_remote=no canary_on_local=no canary_on_remote=no canary_timeout=10 canary_min_packets=5 canary_max_packets=20 canary_interval=10 canary_fails=3 canary_warns=2 canary_status=0 canary_last_status=0 canary_last_change=0 canary_addrtype=any canary_family=inet canary_retries=3 canary_down_interval=30 canary_up_interval=30 canary_src_repair=no canary_dst_repair=no canary_tcp_mss_fixup=no canary_syn_flood_protection=no canary_syn_flood_threshold=5 canary_syn_flood_resets=0 canary_syn_flood_attempts=0 canary_syn_flood_delay=5 canary_syn_flood_wait_time=30 canary_syn_flood_queue_len=64 canary_syn_flood_qlen=-1 canary_syn_flood_qopts=-1 canary_syn_flood_qfull=-1 canary_syn_flood_qempty=-1 canary_syn_flood_qhalf=-1 canary_syn_flood_qspace=-1 canary_syn_flood_qdrain=-1 canary·········································································································································································································································································································································································································································································································································································································································································································································································································································································································································································································································································································································``` 以上信息表示LVS配置已成功。 五、归纳与展望 负载均衡集群通过将请求合理分配到多台服务器上,有效提升了系统的处理能力和可靠性,本文详细介绍了Nginx和LVS两种常见的负载均衡解决方案及其具体搭建步骤,通过实际操作,读者可以掌握如何搭建和维护一个高效的负载均衡集群,随着技术的不断发展,更多优秀的负载均衡技术和工具将涌现,进一步推动互联网应用的发展。
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