数据库 - PostgreSql - 双机热备技术：使用pgpool搭建高可用PostgreSQL HA的步骤

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https://blog.csdn.net/zhousenshan/article/details/52084097?utm_source=blogkpcl4

pgpool，功能比较多，具有连接池，复制，负载均衡，并行查询，和HA等。今天博主测试下HA的配置。环境信息：两台虚拟机，ip分别由192 168 56

双机热备特指基于高可用系统中的两台服务器的热备（或高可用），因两机高可用在国内使用较多，故得名双机热备，双机高可用按工作中的切换方式分为：主-备方式（Active-Standby方式）和双主机方式（Active-Active方式），主-备方式即指的是一台服务器处于某种业务的激活状态（即Active状态），另一台服务器处于该业务的备用状态（即Standby状态)。而双主机方式即指两种不同业务分别在两台服务器上互为主备状态（即Active-Standby和Standby-Active状态）。

pgpool，功能不较多，具有连接池，复制，负载均衡，并行查询，和HA等。今天博主测试下HA的配置。

环境信息：

两台虚拟机，ip分别由192.168.56.101和192.168.56.102 。

PostgreSQL版本：9.3.5

PGHOME：/opt/PostgreSQL/93

PGDATA：/data/pgsql

PGPORT：5432

实验架构：

只有一个pgpool，只测试PostgreSQL热备自动切换功能。

pgpool1

实验步骤

1、准备PostgreSQL环境

在操作之前，需要安装好PostgreSQL，然后配置流复制环境。

这个步骤不明白的朋友可以参考之前的文章。

编译安装PostgreSQL：http://www.sijitao.net/1535.html

PostgreSQL流复制搭建：http://www.sijitao.net/1764.html

2、安装pgpool

pgpool的下载地址：http://www.pgpool.net/download.php?f=pgpool-II-3.3.4.tar.gz 。

tar zxvf pgpool-II-3.3.4.tar.gz

cd pgpool-II-3.3.4

mkdir -p /opt/pgpool

./configure –prefix=/opt/pgpool -with-pgsql=path -with-pgsql=/opt/PostgreSQL/93

make

make install

3、安装pgpool相关函数

pgpool 函数不是必需安装，但建议安装pgpool_regclass,pgpool_recovery 函数。

cd /root/pgpool-II-3.3.4/sql

make

make install

安装完成后可以在/opt/PostgreSQL/93/share/postgresql/extension/看到pgpool相关文件。

root@ubuntu:~/pgpool-II-3.3.4/sql# ls -l /opt/PostgreSQL/93/share/postgresql/extension/

total 36

-rw-r–r– 1 root root 791 Nov 11 11:44 pgpool_recovery–1.0.sql

-rw-r–r– 1 root root 160 Nov 11 11:44 pgpool_recovery.control

-rw-r–r– 1 root root 551 Nov 11 11:44 pgpool-recovery.sql

-rw-r–r– 1 root root 283 Nov 11 11:44 pgpool_regclass–1.0.sql

-rw-r–r– 1 root root 152 Nov 11 11:44 pgpool_regclass.control

-rw-r–r– 1 root root 142 Nov 11 11:44 pgpool-regclass.sql

-rw-r–r– 1 root root 332 Aug 22 11:52 plpgsql–1.0.sql

-rw-r–r– 1 root root 179 Aug 22 11:52 plpgsql.control

-rw-r–r– 1 root root 381 Aug 22 11:52 plpgsql–unpackaged–1.0.sql

登陆需要安装的库中，和安装插件一样执行以下两条命令。

create extension pgpool_regclass;create extension pgpool_recovery;

4、配置两台数据库之间的信任关系

下面这些在两台机器上分别执行，互相登陆不需要密码。

postgres@ubuntu:~$ ssh-keygen

Generating public/private rsa key pair.

Enter file in which to save the key (/home/postgres/.ssh/id_rsa):

Enter passphrase (empty for no passphrase):

Enter same passphrase again:

Your identification has been saved in /home/postgres/.ssh/id_rsa.

Your public key has been saved in /home/postgres/.ssh/id_rsa.pub.

The key fingerprint is:

3d:47:a9:3e:9e:36:5b:ef:2e:0e:21:66:0b:12:76:cd postgres@ubuntu

The key’s randomart image is:

+–[ RSA 2048]—-+

| |

| o . |

| o . E o |

| . o . o |

| . . S = . |

| . + + + |

| . + . |

| .o=.. |

| .++.++ |

+—————–+

postgres@ubuntu:~$ ssh-copy-id postgres@192.168.56.102

The authenticity of host ’192.168.56.102 (192.168.56.102)’ can’t be established.

ECDSA key fingerprint is 8c:f2:97:55:b4:1f:e4:81:1d:55:fd:42:77:3e:c7:c2.

Are you sure you want to continue connecting (yes/no)? yes

Warning: Permanently added ’192.168.56.102′ (ECDSA) to the list of known hosts.

postgres@192.168.56.102′s password:

Now try logging into the machine, with “ssh ‘postgres@192.168.56.102′”, and check in:

~/.ssh/authorized_keys

to make sure we haven’t added extra keys that you weren’t expecting.

5、配置pgpool

root@ubuntu:/opt/pgpool# chown -R postgres:postgres etc/

root@ubuntu:/opt/pgpool# su – postgres

postgres@ubuntu:~$ echo “export PATH=\”\$PATH:/opt/pgpool/bin\”" >>/home/postgres/.bashrc

postgres@ubuntu:~$ source /home/postgres/.bashrc

postgres@ubuntu:~$ cd /opt/pgpool/etc/

a.配置 pcp.conf

pgpool 提供 pcp 接口，可以查看、管理pgpool 的状态，并且可以远程操作pgpool 。pcp.conf是用来对 pcp 相关命令认证的文件，格式为 USERID:MD5PASSWD。

postgres@ubuntu:/opt/pgpool/etc$ cp pcp.conf.sample pcp.conf

postgres@ubuntu:/opt/pgpool/etc$ pg_md5 -upgpool -p

password:

e6a52c828d56b46129fbf85c4cd164b3

在pcp.conf文件中末尾添加pgpool:e6a52c828d56b46129fbf85c4cd164b3 。

b.配置 pgpool.conf

listen_addresses = ‘*’

port = 9999

socket_dir = ‘/tmp’

pcp_port = 9898

pcp_socket_dir = ‘/tmp’

backend_hostname0 = ’192.168.56.101′ //配置数据节点192.168.56.101

backend_port0 = 5432

backend_weight0 = 1 //负载均衡中的权重值

backend_flag0 = ‘ALLOW_TO_FAILOVER’ //允许自动切换

backend_hostname1 = ’192.168.56.102′ //配置数据节点192.168.56.102

backend_port1 = 5432

backend_weight1 = 1

backend_flag1 = ‘ALLOW_TO_FAILOVER’

enable_pool_hba = on //打开pool_passwd

pool_passwd = ‘pool_passwd’

authentication_timeout = 60

ssl = off

num_init_children = 32

max_pool = 4

child_life_time = 300

child_max_connections = 0

connection_life_time = 0

client_idle_limit = 0

log_destination = ‘stderr’

print_timestamp = on

log_connections = on

log_hostname = on

log_statement = on

log_per_node_statement = off

log_standby_delay = ‘none’

syslog_facility = ‘LOCAL0′

syslog_ident = ‘pgpool’

debug_level = 0

pid_file_name = ‘/var/run/pgpool/pgpool.pid’

logdir = ‘/tmp’

connection_cache = on

reset_query_list = ‘ABORT; DISCARD ALL’

replication_mode = off

replicate_select = off

insert_lock = on

lobj_lock_table = ”

replication_stop_on_mismatch = off

failover_if_affected_tuples_mismatch = off

load_balance_mode = on

//负载均衡开关

ignore_leading_white_space = on

white_function_list = ”

black_function_list = ‘nextval,setval’

master_slave_mode = o

n //主备模式开关

master_slave_sub_mode = ‘stream’

//设置流复制模式

sr_check_period = 5

sr_check_user = ‘repuser’

sr_check_password = ’123456′

delay_threshold = 0

follow_master_command = ”

parallel_mode = off

pgpool2_hostname = ”

system_db_hostname = ‘localhost’

system_db_port = 5432

system_db_dbname = ‘pgpool’

system_db_schema = ‘pgpool_catalog’

system_db_user = ‘pgpool’

system_db_password = ”

health_check_period = 0

health_check_timeout = 20

health_check_user = ‘nobody’

health_check_password = ”

health_check_max_retries = 0

health_check_retry_delay = 1

failover_command = ‘/home/postgres/scripts/failover_stream.sh %d %H /data/pgsql/postgresql.trigger.5432′

failback_command = ”

fail_over_on_backend_error = on

search_primary_node_timeout = 10

recovery_user = ‘nobody’

recovery_password = ”

recovery_1st_stage_command = ”

recovery_2nd_stage_command = ”

recovery_timeout = 90

client_idle_limit_in_recovery = 0

use_watchdog = off

trusted_servers = ”

ping_path = ‘/bin’

wd_hostname = ”

wd_port = 9000

wd_authkey = ”

delegate_IP = ”

ifconfig_path = ‘/sbin’

if_up_cmd = ‘ifconfig eth0:0 inet $_IP_$ netmask 255.255.255.0′

if_down_cmd = ‘ifconfig eth0:0 down’

arping_path = ‘/usr/sbin’ # arping command path

arping_cmd = ‘arping -U $_IP_$ -w 1′

clear_memqcache_on_escalation = on

wd_escalation_command = ”

wd_lifecheck_method = ‘heartbeat’

wd_interval = 10

wd_heartbeat_port = 9694

wd_heartbeat_keepalive = 2

wd_heartbeat_deadtime = 30

heartbeat_destination0 = ‘host0_ip1′

heartbeat_destination_port0 = 9694

heartbeat_device0 = ”

wd_life_point = 3

wd_lifecheck_query = ‘SELECT 1′

wd_lifecheck_dbname = ‘template1′

wd_lifecheck_user = ‘nobody’

wd_lifecheck_password = ”

relcache_expire = 0

relcache_size = 256

check_temp_table = on

memory_cache_enabled = off

memqcache_method = ‘shmem’

memqcache_memcached_host = ‘localhost’

memqcache_memcached_port = 11211

memqcache_total_size = 67108864

memqcache_max_num_cache = 1000000

memqcache_expire = 0

memqcache_auto_cache_invalidation = on

memqcache_maxcache = 409600

memqcache_cache_block_size = 1048576

memqcache_oiddir = ‘/var/log/pgpool/oiddir’

white_memqcache_table_list = ”

black_memqcache_table_list = ”

c.failover脚本

/home/postgres/scripts/failover_stream.sh

#! /bin/sh

# Failover command for streaming replication.

# This script assumes that DB node 0 is primary, and 1 is standby.

# If standby goes down, do nothing. If primary goes down, create a

# trigger file so that standby takes over primary node.

# Arguments: $1: failed node id. $2: new master hostname. $3: path to

# trigger file.

failed_node=$1

new_master=$2

trigger_file=$3

# Do nothing if standby goes down.

if [ $failed_node = 1 ]; then

exit 0;

# Create the trigger file./usr/bin/ssh -T $new_master /bin/touch $trigger_file

exit 0;

d.配置pool_hba.conf

postgres@ubuntu:/opt/pgpool/etc$ cppgpool.conf.samplepgpool.conf

这里我把认证权限都设置成md5，和PostgreSQL中的pg_hba.conf一样。

e.配置pool_passwd

配置哪些用户可以通过pgpool登陆数据库，格式user:md5 。

例如：postgres:md5cdf7c8e298f988acbc8d7b6b16cdd5f8 。

6、启动pgpool

启动之前创建两个目录。

mkdir /var/log/pgpool

chown postgres.postgres /var/log/pgpool

mkdir /var/run/pgpool

chown postgres.postgres /var/run/pgpool

启动：

postgres@ubuntu:/opt/pgpool/etc$pgpool -n >/var/log/pgpool/pgpool.log 2>&1 &

7、登陆pgpool、测试HA

postgres@ubuntu:/opt/pgpool/etc$ psql -p 9999 -U postgres -d postgres

psql (9.3.5)

Type “help” for help.

postgres=# show pool_nodes ;

———+—————-+——+——–+———–+———

0 | 192.168.56.101 | 5432 | 2 | 0.500000 | primary

1 | 192.168.56.102 | 5432 | 2 | 0.500000 | standby

(2 rows)

热备和负载均衡这样就配置好了，接下来手动关掉主库。

再次登陆pgpool，查看node状态，可以发现192.168.56.102已经自动切换成primary。

#192.168.56.101

postgres@ubuntu:/opt/pgpool/etc$ psql -p 9999 -U postgres -d postgres

psql (9.3.5)

Type “help” for help.

postgres=# show pool_nodes ;

———+—————-+——+——–+———–+———

0 | 192.168.56.101 | 5432 | 3 | 0.500000 | standby

1 | 192.168.56.102 | 5432 | 2 | 0.500000 | primary

(2 rows)

#192.168.56.102

postgres@ubuntu:/data/pgsql$ ls -l recovery.done-rw-r–r– 1 postgres postgres 4938 Nov 11 11:07 recovery.done

热备自动切换成功。

8、其他问题

如果192.168.56.101重新做了备库后再启动，输入以下命令，status状态变成2 。

/opt/pgpool/bin/pcp_attach_node -d 5 localhost 9898 postgres 123456 0

postgres和密码123456由之前pcp.conf中设置所得。

常见连接异常问题

pg_hba.conf	pool_hba.conf	pool_passwd	result
md5	md5	yes	md5 auth
md5	md5	no	“MD5″ authentication withpgpool failed for user “XX”
md5	trust	yes/no	MD5 authentication is unsupported in replication, master-slave and parallel mode
trust	md5	yes	no auth
trust	md5	no	“MD5″ authentication with pgpool failed for user “XX”
trust	trust	yes/no	no auth