PGSQL主從+keepalived高可用配置
主機與IP：
192.168.11.177 主庫
192.168.11.180 備庫
192.168.11.210 VIP
系統：
centos7.2
PGSQL9.6主從已安裝配置完成（參考我之前的博客）
安裝配置：
1、安裝配置keepalived
主備安裝：
# yum install -y keepalived
主配置：
# vi /etc/keepalived/keepalived.conf
bal_defs {
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id pg
}
vrrp_script chk_pgsql {
script "/etc/keepalived/scripts/pgsql_check.sh"
interval 2
weight -5
fall 2
rise 1
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 61
priority 100
nopreempt
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
chk_pgsql
}
virtual_ipaddress {
192.168.11.210
}
}
備配置：
# vi /etc/keepalived/keepalived.conf
bal_defs {
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id pg
}
vrrp_script chk_pgsql {
script "/etc/keepalived/scripts/pgsql_check.sh"
interval 2
weight -5
fall 2
rise 1
}
vrrp_instance VI_1 {
state BACKUP
interface eth0
virtual_router_id 61
priority 80
nopreempt
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
track_script {
chk_pgsql
}
virtual_ipaddress {
192.168.11.210
}
}
註意：
這裏virtual_router_id按照默認的值51會出錯bogus VRRP packet received on eth0 !!!，所以改值為61。
主備創建目錄和腳本
# mkdir /etc/keepalived/scripts
# vi /etc/keepalived/scripts/pgsql_check.sh
#!/bin/bash
#判斷pg是否活著
A=`ps -C postgres --no-header | wc -l`
#判斷vip浮到哪裏
B=`ip a | grep 192.168.11.210 | wc -l`
#判斷是否是從庫處於等待的狀態
C=`ps -ef | grep postgres | grep 'startup process' | wc -l`
#判斷從庫鏈接主庫是否正常
D=`ps -ef | grep postgres | grep 'receiver' | wc -l`
#判斷主庫連接從庫是否正常
E=`ps -ef | grep postgres | grep 'sender' | wc -l`
#如果pg死了，將消息寫入日記並且關閉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
#判斷出主掛了，vip浮到了從，提升從的地位讓他可讀寫
if [ $B -eq 1 -a $C -eq 1 -a $D -eq 0 ];then
su - postgres -c "pg_ctl promote -D /data/pg_data"
echo "`date "+%Y-%m-%d--%H:%M:%S"` standby promote " >> /etc/keepalived/log/check_pg.log
fi
#判斷出自己是主並且和從失去聯系
if [ $B -eq 1 -a $C -eq 0 -a $D -eq 0 -a $E -eq 0 ];then
sleep 10
echo "`date "+%Y-%m-%d--%H:%M:%S"` can't find standby " >> /etc/keepalived/log/check_pg.log
fi
fi
主備配置日誌：
修改 /etc/sysconfig/keepalived
把KEEPALIVED_OPTIONS="-D" 修改為KEEPALIVED_OPTIONS="-D -d -S 0"
# vi /etc/rsyslog.conf
加入如下配置：
#keepalived -S 0
local0.*/var/log/keepalived.log
主備啟動服務
# systemctl start keepalived.service
# systemctl enable keepalived.service
2、停止主庫服務，並切換主庫為備庫
停止主庫服務，之後發現主庫上的VIP消失，備庫上的VIP生成，備庫變為主庫，可以進行建庫建表等操作。
原來的主庫切換為備庫：
$ cd /data/pg_data
$ rm -rf *
$ pg_basebackup -h 192.168.11.180 -U repuser -D /data/pg_data -X stream -P
$ mv recovery.done recovery.conf
$ vi recovery.conf
primary_conninfo = 'host=192.168.11.177 port=5432 user=repuser password=password123! keepalives_idle=60'
>>
primary_conninfo = 'host=192.168.11.180 port=5432 user=repuser password=password123! keepalives_idle=60'
啟動主機keepalived
# systemctl start keepalived
3、檢查驗證
查看原來備庫服務和庫狀態
$ ps -ef | grep postgres
postgres 1081 1 0 Aug07 ? 00:00:06 /usr/local/postgresql/bin/postgres -D /data/pg_data
postgres 1083 1081 0 Aug07 ? 00:00:01 postgres: checkpointer process
postgres 1084 1081 0 Aug07 ? 00:00:02 postgres: writer process
postgres 1085 1081 0 Aug07 ? 00:00:00 postgres: stats collector process
postgres 13961 1081 0 11:09 ? 00:00:00 postgres: wal writer process
postgres 13962 1081 0 11:09 ? 00:00:00 postgres: autovacuum launcher process
postgres 13963 1081 0 11:09 ? 00:00:00 postgres: archiver process last was 000000020000000000000010
postgres 27065 1081 0 11:25 ? 00:00:00 postgres: wal sender process repuser 192.168.11.177(47074) streaming 0/11000060
root 27922 3590 0 11:26 pts/1 00:00:00 grep --color=auto postgres
postgres=# SELECT pg_is_in_recovery from pg_is_in_recovery();
pg_is_in_recovery
-------------------
f
(1 row)
查看原來主庫服務和庫狀態
$ ps -ef | grep postgres
postgres 2602 1 0 11:25 pts/1 00:00:00 /usr/local/postgresql/bin/postgres -D /data/pg_data
postgres 2603 2602 0 11:25 ? 00:00:00 postgres: startup process recovering 000000020000000000000011
postgres 2604 2602 0 11:25 ? 00:00:00 postgres: checkpointer process
postgres 2605 2602 0 11:25 ? 00:00:00 postgres: writer process
postgres 2606 2602 0 11:25 ? 00:00:00 postgres: stats collector process
postgres 2607 2602 0 11:25 ? 00:00:00 postgres: wal receiver process streaming 0/11000060
postgres 2613 2325 0 11:25 pts/1 00:00:00 grep --color=auto postgres
postgres=# SELECT pg_is_in_recovery from pg_is_in_recovery();
pg_is_in_recovery
-------------------
t
(1 row)
4、測試結果
PGSQL高可用測試結果如下：
高可用方案：
PGSQL 主從 + keepalived
資源：
192.168.11.177 主庫（稱為服務器A）
192.168.11.180 備庫 (稱為服務器B）
192.168.11.210 VIP
1)、模擬A的PGSQL服務停止
B接管VIP（自動）
B由從庫變為主庫（自動）
啟動A的PGSQL服務，並把A配置為備庫（手動）
2)、模擬B的PGSQL服務停止
A接管VIP（自動）
A由從庫變為主庫（自動）
啟動B的PGSQL服務，並把B配置為備庫（手動）
參考：
https://blog.csdn.net/vanilla_he/article/details/79001890
PGSQL主從+keepalived高可用配置