Linux集群架构
| Name | Version |
|---|---|
| CentOS 7 | 3.10.0-693.el7.x86_64 #1 SMP Tue Aug 22 21:09:27 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux |
| Nginx | nginx-1.12.1 |
| keepalived | keepalived.x86_64 0:1.3.5-6.el7 |
集群介绍
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根据功能划分为两大类：高可用和负载均衡
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高可用集群通常为两台服务器，一台工作，另外一台作为冗余，当提供服务的机器宕机，冗余将接替继续提供服务
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实现高可用的开源软件有：heartbeat、keepalived
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负载均衡集群，需要有一台服务器作为分发器，它负责把用户的请求分发给后端的服务器处理，在这个集群里，除了分发器外，就是给用户提供服务的服务器了，这些服务器数量至少为2
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实现负载均衡的开源软件有LVS、keepalived、haproxy、nginx，商业的有F5、Netscaler
keepalived介绍
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在这里我们使用keepalived来实现高可用集群，因为heartbeat在centos6上有一些问题，影响实验效果
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keepalived通过VRRP（Virtual Router Redundancy Protocl）来实现高可用。
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在这个协议里会将多台功能相同的路由器组成一个小组，这个小组里会有1个master角色和N（N>=1）个backup角色。
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master会通过组播的形式向各个backup发送VRRP协议的数据包，当backup收不到master发来的VRRP数据包时，就会认为master宕机了。此时就需要根据各个backup的优先级来决定谁成为新的mater。
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Keepalived要有三个模块，分别是core、check和vrrp。其中core模块为keepalived的核心，负责主进程的启动、维护以及全局配置文件的加载和解析，check模块负责健康检查，vrrp模块是来实现VRRP协议的。
用keepalived配置高可用集群
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准备两台机器128和130，128作为master，130作为backup
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两台机器都执行yum install -y keepalived
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两台机器都安装nginx，其中128上已经编译安装过nginx，130上需要yum安装nginx: yum install -y nginx
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设定vip为100，编辑128上keepalived配置文件，内容从https://coding.net/u/aminglinux/p/aminglinux-book/git/blob/master/D21Z/master_keepalived.conf获取
[root@zyshanlinux-001 ~]# vim /etc/keepalived/keepalived.conf
##快速清空文本的快捷方式##
[root@zyshanlinux-001 ~]# > !$
> /etc/keepalived/keepalived.conf
[root@zyshanlinux-001 ~]# vim /etc/keepalived/keepalived.conf
global_defs {
notification_email {
[email protected]
}
notification_email_from [email protected]
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_script chk_nginx {
script "/usr/local/sbin/check_ng.sh"
interval 3
}
vrrp_instance VI_1 {
state MASTER
interface ens33
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass zyshanlinux>com
}
virtual_ipaddress {
192.168.106.100
}
track_script {
chk_nginx
}
}
-- 插入 --配置文件说明图
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130编辑监控脚本，内容从https://coding.net/u/aminglinux/p/aminglinux-book/git/blob/master/D21Z/master_check_ng.sh获取，给脚本755权限。
##检测脚本是/etc/keepalived/keepalived.conf里面定义的##
[root@zyshanlinux-001 ~]# vim /usr/local/sbin/check_ng.sh
#!/bin/bash
#时间变量，用于记录日志
d=`date --date today +%Y%m%d_%H:%M:%S`
#计算nginx进程数量
n=`ps -C nginx --no-heading|wc -l`
#如果进程为0，则启动nginx，并且再次检测nginx进程数量，
#如果还为0，说明nginx无法启动，此时需要关闭keepalived
if [ $n -eq "0" ]; then
/etc/init.d/nginx start
n2=`ps -C nginx --no-heading|wc -l`
if [ $n2 -eq "0" ]; then
echo "$d nginx down,keepalived will stop" >> /var/log/check_ng.log
systemctl stop keepalived
fi
fi
[root@zyshanlinux-001 ~]# chmod 755 /usr/local/sbin/check_ng.sh
[root@zyshanlinux-001 ~]# ls -l !$
ls -l /usr/local/sbin/check_ng.sh
-rwxr-xr-x 1 root root 567 7月 22 21:52 /usr/local/sbin/check_ng.sh-
128启动keepalived服务
[root@zyshanlinux-001 ~]# ps aux |grep keep
root 1766 0.0 0.0 112720 972 pts/0 S+ 21:57 0:00 grep --color=auto keep
[root@zyshanlinux-001 ~]# systemctl start keepalived
[root@zyshanlinux-001 ~]# ps aux |grep keep
root 1774 0.0 0.0 118652 1396 ? Ss 21:57 0:00 /usr/sbin/keepalived -D
root 1775 0.0 0.1 129580 3304 ? S 21:57 0:00 /usr/sbin/keepalived -D
root 1776 0.3 0.1 129520 2840 ? R 21:57 0:00 /usr/sbin/keepalived -D
root 1789 0.0 0.0 112720 972 pts/0 R+ 21:57 0:00 grep --color=auto keep
[root@zyshanlinux-001 ~]# ps aux |grep nginx
root 1173 0.0 0.0 46032 1280 ? Ss 21:10 0:00 nginx: master process /usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/nginx.conf
nobody 1182 0.0 0.2 48520 4176 ? S 21:10 0:00 nginx: worker process
nobody 1183 0.0 0.2 48520 3920 ? S 21:10 0:00 nginx: worker process
root 1960 0.0 0.0 112720 968 pts/0 R+ 21:58 0:00 grep --color=auto nginxnginx服务即使停止也会自动启动。
[root@zyshanlinux-001 ~]# /etc/init.d/nginx stop
Stopping nginx (via systemctl): [ 确定 ]
[root@zyshanlinux-001 ~]# !ps
ps aux |grep nginx
root 2150 0.0 0.0 46032 1280 ? Ss 22:00 0:00 nginx: master process /usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/nginx.conf
nobody 2154 0.0 0.2 48520 3920 ? S 22:00 0:00 nginx: worker process
nobody 2155 0.0 0.2 48520 3920 ? S 22:00 0:00 nginx: worker process
root 2169 0.0 0.0 112720 972 pts/0 R+ 22:00 0:00 grep --color=auto nginx命令ip add才能看到100的IP，ifconfig就看不到了
检查防火墙是否关闭。
[root@zyshanlinux-001 ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
[root@zyshanlinux-001 ~]# getenforce
Disabled从上也要关闭防火墙。
[root@zyshanlinux-02 ~]# systemctl stop firewalld
[root@zyshanlinux-02 ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
[root@zyshanlinux-02 ~]# getenforce
Enforcing
[root@zyshanlinux-02 ~]# setenforce 0
[root@zyshanlinux-02 ~]# getenforce
Permissive-
130上编辑配置文件，内容从https://coding.net/u/aminglinux/p/aminglinux-book/git/blob/master/D21Z/backup_keepalived.conf获取
[root@zyshanlinux-02 ~]# vim /etc/keepalived/keepalived.conf
[root@zyshanlinux-02 ~]# > !$
> /etc/keepalived/keepalived.conf
[root@zyshanlinux-02 ~]# vim /etc/keepalived/keepalived.conf-
130上编辑监控脚本，内容从https://coding.net/u/aminglinux/p/aminglinux-book/git/blob/master/D21Z/backup_check_ng.sh获取 ，如果你是编译安装的脚本就要用/etc/init.d/nginx start，如果是yum安装的就要用systemctl start nginx，根据实际情况来。
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给脚本755权限，130上也启动服务 systemctl start keepalived
[root@zyshanlinux-02 ~]# chmod 755 !$
chmod 755 /usr/local/sbin/check_ng.sh
[root@zyshanlinux-02 ~]# ls -l !$
ls -l /usr/local/sbin/check_ng.sh
-rwxr-xr-x. 1 root root 555 7月 22 22:30 /usr/local/sbin/check_ng.sh
[root@zyshanlinux-02 ~]# systemctl start keepalived
[root@zyshanlinux-02 ~]# ps aux |grep kee
root 1590 0.0 0.0 118652 1400 ? Ss 22:32 0:00 /usr/sbin/keepalived -D
root 1591 0.0 0.1 127516 3304 ? S 22:32 0:00 /usr/sbin/keepalived -D
root 1592 0.1 0.1 127456 2844 ? S 22:32 0:00 /usr/sbin/keepalived -D
root 1631 0.0 0.0 112720 968 pts/0 R+ 22:32 0:00 grep --color=auto kee
[root@zyshanlinux-02 ~]# systemctl restart keepalived
[root@zyshanlinux-02 ~]# ps aux |grep kee
root 1711 0.0 0.0 118652 1392 ? Ss 22:32 0:00 /usr/sbin/keepalived -D
root 1712 0.0 0.1 127516 3292 ? S 22:32 0:00 /usr/sbin/keepalived -D
root 1713 0.3 0.1 127456 2836 ? S 22:32 0:00 /usr/sbin/keepalived -D
root 1723 0.0 0.0 112724 972 pts/0 S+ 22:32 0:00 grep --color=auto kee区分主从之间的nginx
主：源码包安装nginx的路径
[root@zyshanlinux-001 ~]# cat /data/wwwroot/default/index.html
master master.This is a default site.从：yum安装nginx的路径
[root@zyshanlinux-02 src]# cat /usr/share/nginx/html/index.html
backup backup.virtual_ipaddress:访问的是master，v-ip在master上
测试高可用
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先确定好两台机器上nginx差异，比如可以通过curl -I 来查看nginx版本
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测试1：关闭master上的nginx服务
无法关闭，keepalived会重新启动nginx。
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测试2：在master上增加iptabls规则 ：iptables -I OUTPUT -p vrrp -j DROP
也无法测试出想要的效果，主服务继续启用没有宕机的效果。
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测试3：关闭master上的keepalived服务
主丢失v_ip，查看日志发现keepalived断开的问题
[root@zyshanlinux-001 ~]# ip add
1: lo: mtu 65536 qdisc noqueue state UNKNOWN qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens33: mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:a1:d4:eb brd ff:ff:ff:ff:ff:ff
inet 192.168.106.128/24 brd 192.168.106.255 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.106.100/32 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.106.150/24 brd 192.168.106.255 scope global secondary ens33:0
valid_lft forever preferred_lft forever
inet6 fe80::8fc3:bbdf:ba89:22a7/64 scope link
valid_lft forever preferred_lft forever
3: ens37: mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:a1:d4:f5 brd ff:ff:ff:ff:ff:ff
[root@zyshanlinux-001 ~]# systemctl stop keepalived
[root@zyshanlinux-001 ~]# ip add
1: lo: mtu 65536 qdisc noqueue state UNKNOWN qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens33: mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:a1:d4:eb brd ff:ff:ff:ff:ff:ff
inet 192.168.106.128/24 brd 192.168.106.255 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.106.150/24 brd 192.168.106.255 scope global secondary ens33:0
valid_lft forever preferred_lft forever
inet6 fe80::8fc3:bbdf:ba89:22a7/64 scope link
valid_lft forever preferred_lft forever
3: ens37: mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:a1:d4:f5 brd ff:ff:ff:ff:ff:ff
[root@zyshanlinux-001 ~]# less /var/log/messages
Jul 22 23:54:26 zyshanlinux-001 Keepalived[1774]: Stopping
Jul 22 23:54:26 zyshanlinux-001 systemd: Stopping LVS and VRRP High Availability Monitor...
Jul 22 23:54:26 zyshanlinux-001 Keepalived_vrrp[1776]: VRRP_Instance(VI_1) sent 0 priority
Jul 22 23:54:26 zyshanlinux-001 Keepalived_vrrp[1776]: VRRP_Instance(VI_1) removing protocol VIPs.
Jul 22 23:54:26 zyshanlinux-001 Keepalived_healthcheckers[1775]: Stopped
Jul 22 23:54:27 zyshanlinux-001 Keepalived_vrrp[1776]: Stopped
Jul 22 23:54:27 zyshanlinux-001 systemd: Stopped LVS and VRRP High Availability Monitor.
Jul 22 23:54:27 zyshanlinux-001 Keepalived[1774]: Stopped Keepalived v1.3.5 (03/19,2017), git commit v1.3.5-6-g6fa32f2 从监听v_ip，日志显示具体过程
[root@zyshanlinux-02 src]# ip add
1: lo: mtu 65536 qdisc noqueue state UNKNOWN qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens33: mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:29:ed:0e brd ff:ff:ff:ff:ff:ff
inet 192.168.106.130/24 brd 192.168.106.255 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.106.100/32 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::3c7e:461a:5056:da7d/64 scope link
valid_lft forever preferred_lft forever
3: ens37: mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
link/ether 00:0c:29:29:ed:18 brd ff:ff:ff:ff:ff:ff
[root@zyshanlinux-02 src]# tail /var/log/messages
Jul 22 23:54:31 zyshanlinux-02 Keepalived_vrrp[1733]: Sending gratuitous ARP on ens33 for 192.168.106.100
Jul 22 23:54:31 zyshanlinux-02 Keepalived_vrrp[1733]: Sending gratuitous ARP on ens33 for 192.168.106.100
Jul 22 23:54:31 zyshanlinux-02 Keepalived_vrrp[1733]: Sending gratuitous ARP on ens33 for 192.168.106.100
Jul 22 23:54:31 zyshanlinux-02 Keepalived_vrrp[1733]: Sending gratuitous ARP on ens33 for 192.168.106.100
Jul 22 23:54:36 zyshanlinux-02 Keepalived_vrrp[1733]: Sending gratuitous ARP on ens33 for 192.168.106.100
Jul 22 23:54:36 zyshanlinux-02 Keepalived_vrrp[1733]: VRRP_Instance(VI_1) Sending/queueing gratuitous ARPs on ens33 for 192.168.106.100
Jul 22 23:54:36 zyshanlinux-02 Keepalived_vrrp[1733]: Sending gratuitous ARP on ens33 for 192.168.106.100
Jul 22 23:54:36 zyshanlinux-02 Keepalived_vrrp[1733]: Sending gratuitous ARP on ens33 for 192.168.106.100
Jul 22 23:54:36 zyshanlinux-02 Keepalived_vrrp[1733]: Sending gratuitous ARP on ens33 for 192.168.106.100
Jul 22 23:54:36 zyshanlinux-02 Keepalived_vrrp[1733]: Sending gratuitous ARP on ens33 for 192.168.106.100 -
测试4：启动master上的keepalived服务
主：重新监听v_ip
[root@zyshanlinux-001 ~]# systemctl start keepalived
[root@zyshanlinux-001 ~]# ip add
1: lo: mtu 65536 qdisc noqueue state UNKNOWN qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens33: mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:a1:d4:eb brd ff:ff:ff:ff:ff:ff
inet 192.168.106.128/24 brd 192.168.106.255 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.106.100/32 scope global ens33
valid_lft forever preferred_lft forever
inet 192.168.106.150/24 brd 192.168.106.255 scope global secondary ens33:0
valid_lft forever preferred_lft forever
inet6 fe80::8fc3:bbdf:ba89:22a7/64 scope link
valid_lft forever preferred_lft forever
3: ens37: mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:a1:d4:f5 brd ff:ff:ff:ff:ff:ff
inet6 fe80::7285:a690:d34:bb0c/64 scope link
valid_lft forever preferred_lft forever 从：丢失v_ip
[root@zyshanlinux-02 src]# ip add
1: lo: mtu 65536 qdisc noqueue state UNKNOWN qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens33: mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:29:ed:0e brd ff:ff:ff:ff:ff:ff
inet 192.168.106.130/24 brd 192.168.106.255 scope global ens33
valid_lft forever preferred_lft forever
inet6 fe80::3c7e:461a:5056:da7d/64 scope link
valid_lft forever preferred_lft forever
3: ens37: mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
link/ether 00:0c:29:29:ed:18 brd ff:ff:ff:ff:ff:ff
负载均衡集群介绍
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主流开源软件LVS、keepalived、haproxy、nginx等
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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
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keepalived的负载均衡功能其实就是lvs
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lvs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
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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
LVS介绍
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LVS是由国人章文嵩开发
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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
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LVS最新版本基于Linux内核2.6，有好多年不更新了
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LVS有三种常见的模式：NAT、DR、IP Tunnel
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LVS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的调度算法
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轮询 Round-Robin rr
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加权轮询 Weight Round-Robin wrr
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最小连接 Least-Connection lc
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加权最小连接 Weight Least-Connection wlc
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基于局部性的最小连接 Locality-Based Least Connections lblc
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带复制的基于局部性最小连接 Locality-Based Least Connections with Replication lblcr
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目标地址散列调度 Destination Hashing dh
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源地址散列调度 Source Hashing sh
LVS NAT模式搭建
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133.130 rs2 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 firewalld systemctl start iptables-services; iptables -F; service iptables save
在dir上安装ipvsadm yum install -y ipvsdam 在dir上编写脚本，vim /usr/local/sbin/lvs_nat.sh//内容如下
#! /bin/bash
# director 服务器上开启路由转发功能
echo 1 > /proc/sys/net/ipv4/ip_forward
# 关闭icmp的重定向
echo 0 > /proc/sys/net/ipv4/conf/all/send_redirects
echo 0 > /proc/sys/net/ipv4/conf/default/send_redirects
# 注意区分网卡名字，阿铭的两个网卡分别为ens33和ens37
echo 0 > /proc/sys/net/ipv4/conf/ens33/send_redirects
echo 0 > /proc/sys/net/ipv4/conf/ens37/send_redirects
# director 设置nat防火墙
iptables -t nat -F
iptables -t nat -X
iptables -t nat -A POSTROUTING -s 192.168.133.0/24 -j MASQUERADE
# director设置ipvsadm
IPVSADM='/usr/sbin/ipvsadm'
$IPVSADM -C
$IPVSADM -A -t 192.168.147.144:80 -s wlc -p 3
$IPVSADM -a -t 192.168.147.144:80 -r 192.168.133.132:80 -m -w 1
$IPVSADM -a -t 192.168.147.144:80 -r 192.168.133.133:80 -m -w 1
NAT模式效果测试
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
拓展：
keepalived 默认报警设置使用外部邮箱http://blog.51cto.com/6764097/1954158
HAProxy+Keepalived配置邮件报警，会话保存机制和TCP端口范围(三)
https://blog.csdn.net/HzSunshine/article/details/62052398
LVS介绍及工作原理图解http://blog.51cto.com/jiekeyang/1839583