构建高可用集群Keepalived+Haproxy
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重点概念
vrrp_script中节点权重改变算法
vrrp_script 里的script返回值为0时认为检测成功，其它值都会当成检测失败；
weight 为正时，脚本检测成功时此weight会加到priority上，检测失败时不加；
主失败:
主 priority < 从 priority + weight 时会切换。
主成功：
主 priority + weight > 从 priority + weight 时，主依然为主
weight 为负时，脚本检测成功时此weight不影响priority，检测失败时priority – abs(weight)
主失败:
主 priority – abs(weight) < 从priority 时会切换主从
主成功:
主 priority > 从priority 主依然为主
主要贴配置：
一台：
vi /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
}
notification_email_from [email protected]
smtp_connect_timeout 3
smtp_server 127.0.0.1
router_id Iptables
}
vrrp_script chk_maintaince_down {
script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"
interval 1
weight 2
}
vrrp_script chk_haproxy {
script "killall -0 haproxy"
interval 1
weight 2
}
vrrp_instance VI_1 {
interface eth0
state MASTER
priority 100
virtual_router_id 125
garp_master_delay 1
authentication {
auth_type PASS
auth_pass 1e3459f77aba4ded
}
track_interface {
eth0
}
virtual_ipaddress {
10.16.37.198/22 dev eth0 label eth0:0
}
track_script {
chk_haproxy
}
notify_master "/etc/keepalived/notify.sh master 10.16.37.198"
notify_fault "/etc/keepalived/notify.sh fault 10.16.37.198"
}
vrrp_instance VI_2 {
interface eth0
state BACKUP
priority 99
virtual_router_id 126
grap_master_delay 1
authentication {
auth_type pass
auth_pass 7615c4b7f518cede
}
track_interface {
eth0
}
virtual_ipaddress {
10.16.37.199/22 dev eth0 label eth0:1
}
track_script {
chk_haproxy
chK_maintaince_down
}
notify_master "/etc/keepalived/notify.sh master 10.16.37.199"
notify_backup "/etc/keepalived/notify.sh backup 10.16.37.199"
notify_fault "/etc/keepalived/notify.sh fault 10.16.37.199"
}
另一台：vi /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
}
notification_email_from [email protected]
smtp_connect_timeout 3
smtp_server 127.0.0.1
router_id Iptables
}
vrrp_script chk_maintaince_down {
script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"
interval 1
weight 2
}
vrrp_script chk_haproxy {
script "killall -0 haproxy"
interval 1
weight 2
}
vrrp_instance VI_1 {
interface eth0
state BACKUP
priority 99
virtual_router_id 125
garp_master_delay 1
authentication {
auth_type PASS
auth_pass 1e3459f77aba4ded
}
track_interface {
eth0
}
virtual_ipaddress {
10.16.37.198/22 dev eth0 label eth0:1
}
track_script {
chk_haproxy
}
notify_master "/etc/keepalived/notify.sh master 10.16.37.198"
notify_fault "/etc/keepalived/notify.sh fault 10.16.37.198"
}
vrrp_instance VI_2 {
interface eth0
state MASTER
priority 100
virtual_router_id 126
grap_master_delay 1
authentication {
auth_type pass
auth_pass 7615c4b7f518cede
}
track_interface {
eth0
}
virtual_ipaddress {
10.16.37.199/22 dev eth0 label eth0:0
}
track_script {
chk_haproxy
chK_maintaince_down
}
notify_master "/etc/keepalived/notify.sh master 10.16.37.199"
notify_backup "/etc/keepalived/notify.sh backup 10.16.37.199"
notify_fault "/etc/keepalived/notify.sh fault 10.16.37.199"
}
脚本配置：
vi /etc/keepalived/notify.sh
#!/bin/bash
contact=‘[email protected]‘
notify() {
mailsubject="‘hostname‘ to be $1: $2 floating"
mailbody="‘date ‘+%F %H:%M:%S‘`: vrrp transition, `hostname` changed to be $1"
echo $mailbody | mail -s "$mailsubject" $contact
}
case "$1" in
master)
notify master $2
/etc/rc.d/init.d/haproxy restart
exit 0
;;
backup)
notify backup $2
exit 0
;;
fault)
notify fault $2
exit 0
;;
*)
echo ‘Usage: ‘basename $0‘ {master|backup|fault}‘
exit 1
;;
Esac
Haproxy配置：
vi /etc/haproxy/haproxy.cfg
#---------------------------------------------------------------------
# Example configuration for a possible web application. See the
# full configuration options online.
#
# http://haproxy.1wt.eu/download/1.4/doc/configuration.txt
#
#---------------------------------------------------------------------
#---------------------------------------------------------------------
# Global settings
#---------------------------------------------------------------------
global
# to have these messages end up in /var/log/haproxy.log you will
# need to:
#
# 1) configure syslog to accept network log events. This is done
# by adding the ‘-r‘ option to the SYSLOGD_OPTIONS in
# /etc/sysconfig/syslog
#
# 2) configure local2 events to go to the /var/log/haproxy.log
# file. A line like the following can be added to
# /etc/sysconfig/syslog
#
# local2.* /var/log/haproxy.log
#
log 127.0.0.1 local2
chroot /var/lib/haproxy
pidfile /var/run/haproxy.pid
maxconn 4000
user haproxy
group haproxy
daemon
# turn on stats unix socket
stats socket /var/lib/haproxy/stats
#---------------------------------------------------------------------
# common defaults that all the ‘listen‘ and ‘backend‘ sections will
# use if not designated in their block
#---------------------------------------------------------------------
defaults
mode http
log global
option httplog
option dontlognull
option http-server-close
option forwardfor except 127.0.0.0/8
option redispatch
retries 3
timeout http-request 10s
timeout queue 1m
timeout connect 10s
timeout client 1m
timeout server 1m
timeout http-keep-alive 10s
timeout check 10s
maxconn 3000
#---------------------------------------------------------------------
# main frontend which proxys to the backends
#---------------------------------------------------------------------
#frontend main *:5000
# acl url_static path_beg -i /static /images /javascript /stylesheets
# acl url_static path_end -i .jpg .gif .png .css .js
#
# use_backend static if url_static
# default_backend app
#---------------------------------------------------------------------
# static backend for serving up images, stylesheets and such
#---------------------------------------------------------------------
#backend static
# balance roundrobin
# server static 127.0.0.1:4331 check
#---------------------------------------------------------------------
# round robin balancing between the various backends
#---------------------------------------------------------------------
#backend app
# balance roundrobin
# server app1 127.0.0.1:5001 check
# server app2 127.0.0.1:5002 check
# server app3 127.0.0.1:5003 check
# server app4 127.0.0.1:5004 check
listen stats
mode http
bind 0.0.0.0:1080
stats enable
stats refresh 30s
maxconn 200
stats hide-version
stats uri /haproxy-stats
stats realm Haproxy\ Statistics
stats auth admin:admin
stats admin if TRUE
frontend http-in
bind *:80
mode http
log global
option httpclose
option logasap
option dontlognull
capture request header Host len 20
capture request header Referer len 60
acl url_static path_beg -i /static /images /javascript /stylesheets
acl url_static path_end -i .jpg .jpeg .gif .png .css .js .html
use_backend static_servers if url_static
default_backend dynamic_servers
backend static_servers
balance roundrobin
server imgsrv1 10.16.37.101:80 check maxconn 6000
server imgsrv2 10.16.37.94:80 check maxconn 6000
backend dynamic_servers
balance source
server websrv1 10.16.37.94:80 check maxconn 1000
server websrv2 10.16.37.101:80 check maxconn 1000
因为端口使用的是1080需要Iptables开启：
/sbin/iptables –I INPUT –p tcp –dport 1080 –j ACCEPT
/etc/rc.d/init.d/iptables save
Service iptables restart
Vi /etc/selinux/config
关闭selinux然后呢重启！！
二个server web采用nginx+双主mysql数据库，保证了web服务器的高可用性能，一台服务器宕机，另外一台立马连接！！
参考：
http://www.it165.net/admin/html/201405/2957.html
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