postgresql+keepalived高可用部署

postgresql+keepalived高可用部署（基于postgresql流复制部署）

基于流复制部署，keepalived检测postgresql状态，如果pgsql死了，那么keepalived的VIP漂移到备库，同时提升备库为主库，可以进行读写操作。（默认流复制的主库为可读可写，备库为只读）
主库：192.168.19.73
备库：192.168.19.74
VIP：192.168.19.250
流复制部署完毕后（流复制部署以及测试请看上一章），安装keepalived

1.主备安装keepalived

yum install -y keepalived

2.查看安装文件位置

whereis keepalived
输出信息如下：keepalived: /usr/sbin/keepalived /etc/keepalived /usr/libexec/keepalived /usr/share/man/man8/keepalived.8.gz

3.修改keepalived.conf配置文件

1 ! Configuration File for keepalived
2 
3 global_defs {
     
4    notification_email {
     
5      *******@163.com
6    }
7    notification_email_from Alexandre.Cassen@localhost
8    smtp_server mail.server.intelli.com
9    smtp_connect_timeout 30
10    router_id pg_73     #注意主备不一样
11    vrrp_skip_check_adv_addr
12 #  vrrp_strict          #注释掉此处，避免keepalived启动后iptables drop vip
13    vrrp_garp_interval 0
14    vrrp_gna_interval 0
15 }
16 #1-16行为邮箱设置，可以简单设置或者忽略。
17 vrrp_script check_pg_alived {
     
18         script "/etc/keepalived/scripts/check_pg.sh"   #检测脚本位置
19         interval 2
20         weight -5
21         fall 2
22         rise 1
23 }
24 
25 vrrp_instance VI_1 {
     
26     state BACKUP      #主备一致
27     interface eth0  
28     virtual_router_id 50  #默认51，保持主备一致即可
29     priority 100          #优先级主高于备即可
30     advert_int 1
31     authentication {
     
32         auth_type PASS
33         auth_pass HT706   #密码主备一致
34     }
35     track_script {
     
36         check_pg_alived
37     }
38     virtual_ipaddress {
     
39         192.168.19.250   #VIP
40     }
41 }
42 }

4.主备脚本内容如下

cat /etc/keepalived/scripts/check_pg.sh
		#!/bin/bash
		#判断pg是否活着
		A=`ps -C postgres --no-header | wc -l`

		#判断vip浮到哪里
		B=`ip a | grep 192.168.19.250 | wc -l`

		#判断是否是从库处于等待的状态
		C=`ps -ef | grep postgres | grep 'startup process' | wc -l`

		#判断从库链接主库是否正常
		D=`ps -ef | grep postgres | grep 'receiver' | wc -l`

		#判断主库连接从库是否正常
		E=`ps -ef | grep postgres | grep 'sender' | wc -l`

		#如果pg死了，将消息写入日记并且关闭keepalived
		if [ $A -eq 0 ];then
			echo "`date "+%Y-%m-%d--%H:%M:%S"` postgresql stop so vip stop " >> /etc/keepalived/log/check_pg.log
			systemctl stop keepalived
		else

				#判断出主ku挂了，vip漂移到了从，提升从的地位让他可读写
				if [ $B -eq 1 -a $C -eq 1 -a $D -eq 0 ];then
					su - postgres -c "pg_ctl promote -D /var/lib/pgsql/data/"   #重新加载pgsql使其可写
					echo "`date "+%Y-%m-%d--%H:%M:%S"` standby promote " >> /etc/keepalived/log/check_pg.log
				fi

				#判断出自己是主并且和从失去联系
				if [ $B -eq 1 -a $C -eq 0 -a $D -eq 0 -a $E -eq 0 ];then
					echo "`date "+%Y-%m-%d--%H:%M:%S"` can't find standby " >> /etc/keepalived/log/check_pg.log
				fi
		fi

5.修改keepalived配置

1)修改 /etc/sysconfig/keepaliveddel;把KEEPALIVED_OPTIONS="-D" 修改为KEEPALIVED_OPTIONS="-D -d -S 0"

2)# vi /etc/rsyslog.conf

加入如下配置：

#keepalived -S 0
local0.*/var/log/keepalived.log

6.启动keepalived服务检查VIP情况

systemctl start keepalived  && systemctl  enable keepalived
ip addr   #主库（192.168.19.73）有vip备库（192.168.19.74）无vip

7.关闭SELINUX和防火墙

systemctl stop firewalld  && systemctl disable firewalld
setenforce 0 ##永久关闭修改vim /etc/sysconfig/selinux

8.检测

1)查看主库与备库的数据库是否一致，并在主库上写入数据，再到备库上查看是否同步过去了。确定同步没有问题（流复制检查）
2)使用vip连接数据库并写入数据
psql -h 192.168.19.250 -U postgres
create table test(id int);   创建test表
insert into test values (1),(2);   插入数据
3)主备查看数据
select * from test；
4)模拟主库宕机，检测备库情况
systemctl stop postgresql  #停掉主库（192.168.19.73）
检查vip在哪一台主机，连接vip再次插入数据，如果可以写入数据则表示备库切换主库成功；
insert into test values (3);  
现在只有一台运行（74）

9.将坏掉的主库（192.168.19.73）修改为备库

1)删除数据或者mv备份
rm -rf  /var/lib/pgsql/data/*
2)同步主库数据
pg_basebackup -D /var/lib/pgsql/data/ -F p -X stream -v -P -h 192.168.19.74 -U replica   #IP为现在运行主库IP地址
3)修改recovery.conf文件指定主库ip
mv  recovery.done  recovery.conf
vim recovery.conf
standby_mode='on'
primary_conninfo = 'host=192.168.19.73 port=5432 user=replica password=replica'     #将该ip指定主库ip地址
restore_command = ''
recovery_target_timeline = 'latest'
4)启动pgsql
chown -R postgres.postgers  /var/lib/pgsql   #同步过来的属主属组为root修改为poatgres
systemctl restart  postgresql
	
注：部署还不够完美，这里还没有启动keepalived，当启动后vip又漂移会来；需要手动降级

注：本人写了一个将宕机的主库添加为从库脚本（第9步也可以执行脚本即可）脚本内容如下
vim /postgresql/pqsql.sh #只可以执行一次，注意IP地址修改

#!/bin/bash
rm -rf /var/lib/pgsql/data/*  && echo "数据删除成功"  || echo "数据删除发生错误"   #也可以将数据备份
sleep 0.5
#同步主库数据,ip为主库ip
pg_basebackup -D /var/lib/pgsql/data/ -F p -X stream -v -P -h 192.168.19.74 -U replica &> /dev/null  && echo “数据同步成功”  || echo  “数据同步发生错误”
sleep 1
mv /var/lib/pgsql/data/recovery.done /var/lib/pgsql/data/recovery.conf  && sed -i "s/192.168.19.73/192.168.19.74/g"  /var/lib/pgsql/data/recovery.conf  && echo "文件recovery.conf修改成功"  || echo "文件recovery.conf修改失败"
chown -R postgres.postgres /var/lib/pgsql
sleep 0.5
systemctl restartt postgresql  && echo "pgsql start success"  || echo "pgsql start fial"
sleep 1
echo "提示：请去修改keepalived优先级(/etc/keepalived/keepalived.conf)！！！然后开启keepalived！！！"