PostgreSQL流复制实现HA主备切换
环境说明和主机规划
操作系统 | 主机名 | 主机 | 角色 | 端口 |
---|---|---|---|---|
CentOS 7 | master | 10.0.0.11 | PG-Master | 54321 |
CentOS 7 | slave | 10.0.0.12 | PG-Slave | 54321 |
CentOS 7 | pool | 10.0.0.13 | pgpool | 54321 |
基础环境配置(所有主机操作)
配置HOSTS
echo -e "10.0.0.11 master\n10.0.0.12 slave\n10.0.0.13 pool" >> /etc/hosts # 执行一次即可
配置统一的时间(若已配置,请忽略)
yum install -y ntpdate && ntpdate ntp1.aliyun.com echo -e "# sync time from ntp1.aliyun.com\n5 * * * * /usr/sbin/ntpdate ntp1.aliyun.com > /dev/null 2>&1 " >> /var/spool/cron/root # 写入定时任务,执行一次即可
创建postgres用户
useradd postgres && echo "your_password" | passwd --stdin postgres
配置免密钥登陆
su - postgres ssh-keygen -t rsa -f /home/postgres/.ssh/id_rsa -P "" cd ~/.ssh/ ssh-copy-id postgres@master # 三台主机执行 scp authorized_keys postgres@slave:~/.ssh # 只在master主机执行 scp authorized_keys postgres@pool:~/.ssh # 只在master主机执行
安装Postgresql数据库(PG9.6)
yum install -y https://download.postgresql.org/pub/repos/yum/9.6/redhat/rhel-7-x86_64/pgdg-centos96-9.6-3.noarch.rpm
yum install -y postgresql96-server postgresql96-contrib postgresql96 postgresql96-libs
创建统一的目录结构
mkdir /data1/pg_{data,bin,logs} -p
chown -R postgres.postgres /data1/
修改系统变量
vi /etc/profile #增加以下内容 export PGHOME=/usr/pgsql-9.6/ export PGDATA=/data1/pg_data export PGPORT=54321 export PATH=$PATH:$PGHOME/bin # 生效 source /etc/profile
PostgreSQL流复制结构(master和slave主机操作)
master主机操作
初始化系统
/usr/pgsql-9.6/bin/postgresql96-setup initdb
vi /usr/lib/systemd/system/postgresql-9.6.service
修改postgresql-9.6.service
内容如下:
# Include the default config: .include /usr/lib/systemd/system/postgresql-9.6.service [Service] Environment=PGDATA=/data1/pg_data
重启PG服务
systemctl daemon-reload su - postgres -c '/usr/pgsql-9.6/bin/initdb -D /data1/pg_data' systemctl restart postgresql-9.6 systemctl enable postgresql-9.6.service
修改系统配置(以下用postgres用户操作)
cp /data1/pg_data/pg_hba.conf{,.bak} cat >/data1/pg_data/pg_hba.conf<
64G
cp /data1/pg_data/postgresql.conf{,.bak} cat >/data1/pg_data/postgresql.conf<
128G
listen_addresses = '*' port = 54321 max_connections = 256 shared_buffers = 32GB effective_cache_size = 96GB work_mem = 128MB maintenance_work_mem = 2GB min_wal_size = 2GB max_wal_size = 4GB checkpoint_completion_target = 0.9 wal_buffers = 16MB default_statistics_target = 100 wal_level = hot_standby wal_log_hints = on max_wal_senders = 1 hot_standby = on logging_collector = on log_directory = 'pg_log'
在主库中创建流复制用户(stream_replication)和PGPool用户(srcheck)
CREATE USER stream_replication replication LOGIN CONNECTION LIMIT 5 ENCRYPTED PASSWORD 'your_password';
CREATE USER srcheck replication LOGIN CONNECTION LIMIT 5 ENCRYPTED PASSWORD 'your_password';
修改主库pg_hba.conf文件(已操作见cat >/data1/pg_data/pg_hba.conf< host replication stream_replication 0.0.0.0/0 md5 slave主机操作 初始化系统 /usr/pgsql-9.6/bin/postgresql96-setup initdb vi /usr/lib/systemd/system/postgresql-9.6.service 修改postgresql-9.6.service 内容如下: 重启PG服务 systemctl daemon-reload 基础备份复制到备库服务器 rm -rf /data1/pg_data # 如果没有重要数据可操作,主要为同步主库路径 su - postgres -c 'pg_basebackup -D $PGDATA --format=p -h master -p 54321 -U stream_replication -W' 修改备库配置信息 cp $PGHOME/share/recovery.conf.sample $PGDATA/recovery.conf vi $PGDATA/recovery.conf 增加以下内容 验证 主节点执行 备节点执行 select * from test; 其他查询 进入测试数据库test,主库上执行如下命令返回f,备库上返回t。 select pg_is_in_recovery(); 执行如下命令查看快照,它返回主库记录点、备库记录点;主库每增加一条写入,记录点的值就会加1。 select txid_current_snapshot(); 执行如下命令可以查看主备同步状态。 select * from pg_stat_replication; 字段state显示的同步状态有:startup(连接中)、catchup(同步中)、streaming(同步);字段sync_state显示的模式有:async(异步)、sync(同步)、potential(虽然现在是异步模式,但是有可能升级到同步模式)。 假设主库崩溃了,备库如何从只读状态切换为读写状态呢?只要把备库的postgresql.conf中hot_standby修改为off,并且删除recovery.conf,然后重启库就可以提供服务了。 PGPool2(pool主机操作) 安装PGPool2 添加Pgpool-II运行用户 配置pool_hba.conf cp /etc/pgpool-II/pool_hba.conf{,.bak} vi /etc/pgpool-II/pool_hba.conf 增加内容 host all all 0.0.0.0/0 md5 配置pcp.conf 主节点登陆后执行: vi /etc/pgpool-II/pool_passwd 增加SQL执行结果的内容,形式为$rolname:$rolpassword例如: srcheck:md5662c10f61b27a9ab38ce69157186b25f 或者: pg_md5 -u postgres your_password vi /etc/pgpool-II/pcp.conf ## 加入 postgres:上一命令的输出 配置pgpool.conf cp /etc/pgpool-II/pgpool.conf{,.bak} vi /etc/pgpool-II/pgpool.conf 内容如下: failover_stream.sh脚本 failover_stream.sh内容: 登陆设置 当执行pgpool -n -d -D > /data1/pg_logs/pgpool.log 2>&1 &后可查看集群状态: 如果未发现集群状态,请在master和slave主机分别执行以下操作: 模拟master主机宕机 Master端: 当前集群状态 发现master已经是standby了,且down机了 修改master,启动 当master主机宕机后,此时slave主机PG数据库成为主库,修改master成为slave的从库即可 同步时间线 再次查看当前状态 现在两个节点都是up了。 主从两节点pgpool健康检查脚本(pgpool_check.sh) 说明:此脚本是基于PGpool只安装到master和slave两个主机上的情况下使用,在master主机有了pgpool进程后,可在slave主机执行sh pgpool_check.sh & 即可 以上为个人经验,希望能给大家一个参考,也希望大家多多支持脚本之家。如有错误或未考虑完全的地方,望不吝赐教。
# Include the default config:
.include /usr/lib/systemd/system/postgresql-9.6.service
[Service]
Environment=PGDATA=/data1/pg_data
standby_mode='on'
primary_conninfo = 'host=master port=54321 user=stream_replication password=your_password'
restore_command = ''
recovery_target_timeline = 'latest'
# 重启PG服务
systemctl restart postgresql-9.6
systemctl enable postgresql-9.6.service
create table test (id int4, create_time timestamp(0) without time zone);
insert into test values (1, now());
select * from test;
主备切换
yum install -y http://www.pgpool.net/yum/rpms/3.6/redhat/rhel-7-x86_64/pgpool-II-release-3.6-1.noarch.rpm
yum -y install pgpool-II-pg96 pgpool-II-pg96-debuginfo pgpool-II-pg96-devel pgpool-II-pg96-extensions
systemctl enable pgpool.service #开启自动启动
useradd postgres # 环境准备时已操作
chown -R postgres.postgres /etc/pgpool-II
chown -R postgres.postgres /var/run/pgpool/
postgres=# select rolname,rolpassword from pg_authid;
rolname | rolpassword
--------------------+-------------------------------------
pg_signal_backend |
srcheck | md5662c10f61b27a9ab38ce69157186b25f
postgres | md5d3612d57ee8d4c147cf27b11e3a0974d
stream_replication | md59279ef6b904bc483e4f85e6d44cfc0ed
(4 rows)
# CONNECTIONS
listen_addresses = '*'
port = 54321
socket_dir = '/var/run/pgpool'
pcp_listen_addresses = '*'
pcp_port = 9898
pcp_socket_dir = '/var/run/pgpool'
# - Backend Connection Settings -
backend_hostname0 = 'master'
backend_port0 = 54321
backend_weight0 = 1
backend_data_directory0 = '/data1/pg_data'
backend_flag0 = 'ALLOW_TO_FAILOVER'
backend_hostname1 = 'slave'
backend_port1 = 54321
backend_weight1 = 1
backend_data_directory1 = '/data1/pg_data'
backend_flag1 = 'ALLOW_TO_FAILOVER'
# - Authentication -
enable_pool_hba = on
pool_passwd = 'pool_passwd'
# FILE LOCATIONS
pid_file_name = '/var/run/pgpool/pgpool.pid'
logdir = '/data1/pg_logs'
replication_mode = off
load_balance_mode = on
master_slave_mode = on
master_slave_sub_mode = 'stream'
sr_check_period = 5
sr_check_user = 'srcheck'
sr_check_password = '123456'
sr_check_database = 'postgres'
# HEALTH CHECK 健康检查
health_check_period = 10
health_check_timeout = 20
health_check_user = 'srcheck'
health_check_password = '123456'
health_check_database = 'postgres'
# FAILOVER AND FAILBACK
failover_command = '/data1/pg_bin/failover_stream.sh %H'
vim /data1/pg_bin/failover_stream.sh
chmod 777 /data1/pg_bin/failover_stream.sh
chmod u+s /sbin/ifconfig
chmod u+s /usr/sbin
pgpool -n -d -D > /data1/pg_logs/pgpool.log 2>&1 & ## 启动
pgpool -m fast stop ## 关闭
#! /bin/sh
# Failover command for streaming replication.
# Arguments: $1: new master hostname.
new_master=$1
trigger_command="$PGHOME/bin/pg_ctl promote -D $PGDATA"
# Prompte standby database.
/usr/bin/ssh -T $new_master $trigger_command
exit 0;
[postgres@pool pgpool-II]$ psql -p 54321 -h 10.0.0.13 -U srcheck -d postgres
postgres=# show pool_nodes;
node_id | hostname | port | status | lb_weight | role | select_cnt | load_balance_node | replication_delay
---------+----------+-------+--------+-----------+---------+------------+-------------------+-------------------
0 | master | 54321 | up | 0.500000 | primary | 0 | false | 0
1 | slave | 54321 | up | 0.500000 | standby | 0 | true | 0
(2 rows)
[postgres@pool ~]$ pcp_attach_node -d -U postgres -h pool -p 9898 -n 0
[postgres@pool ~]$ pcp_attach_node -d -U postgres -h pool -p 9898 -n 1
#详情查询命令pcp_attach_node
HA切换
[postgres@master ~]$ pg_ctl stop
waiting for server to shut down.... done
server stopped
[postgres@pool ~]$ psql -p 54321 -h 10.0.0.13 -U srcheck -d postgres
psql (9.6.1)
Type "help" for help.
postgres=# show pool_nodes;
node_id | hostname | port | status | lb_weight | role | select_cnt | load_balance_node | replication_delay
---------+----------+------+--------+-----------+---------+------------+-------------------+-------------------
0 | master | 5432 | down| 0.500000 | standby | 0 | false | 0
1 | slave | 5432 | up | 0.500000 | primary | 0 | true | 0
(2 rows)
[postgres@master ~]$ vim recovery.conf
standby_mode='on'
primary_conninfo = 'host=slave port=54321 user=stream_replication password=your_password'
restore_command = ''
recovery_target_timeline = 'latest'
#如果报时间线冲突落后,先停掉pg服务,然后执行同步时间线,否知直接看状态
[postgres@master ~]$ pg_rewind --target-pgdata=/data1/pg_data --source-server='host=slave port=54321 user=postgres dbname=postgres'
servers diverged at WAL position 0/5000098 on timeline 1
rewinding from last common checkpoint at 0/5000028 on timeline 1
Done!
# 重新启动数据库
[postgres@master ~]$ pg_ctl start
[postgres@pool ~]$ psql -p 54321 -h 10.0.0.13 -U srcheck -d postgres
postgres=# show pool_nodes;
node_id | hostname | port | status | lb_weight | role | select_cnt | load_balance_node | replication_delay
---------+----------+------+--------+-----------+---------+------------+-------------------+-------------------
0 | master | 5432 | down| 0.500000 | standby | 0 | false | 0
1 | slave | 5432 | up | 0.500000 | primary | 0 | true | 0
(2 rows)
#注意虽然master已经启动了,但是还是down,需要手动将master节点添加进pgpool,master的node_id是0,所以-n 0
[postgres@pool ~]$ pcp_attach_node -d -U postgres -h pool -p 54321 -n 0
#提示输入密码,输入pcp管理密码
#查看当前状态
[postgres@pool ~]$ psql -p 54321 -h 10.0.0.13 -U srcheck -d postgres
postgres=# show pool_nodes;
node_id | hostname | port | status | lb_weight | role | select_cnt | load_balance_node | replication_delay
---------+----------+------+--------+-----------+---------+------------+-------------------+-------------------
0 | master | 5432 | up | 0.500000 | standby | 0 | false | 0
1 | slave | 5432 | up | 0.500000 | primary | 0 | true | 0
(2 rows)
#! /bin/bash
# Check Master host pgpool-process
while true
do
pgcount=$(nmap 10.0.0.11|egrep '9898|9999'|wc -l)
if [ $pgcount -eq 2 ] ; then
echo 'Master host pgpool is GOOD!!!' > /dev/null 2>&1
else
echo -e "Master host pgpool is \033[31m BAD!!! \033[0m"
echo -e "Master host pgpool is \033[31m BAD!!! \033[0m"
echo -e "Master host pgpool is \033[31m BAD!!! \033[0m"
echo -e "SYSTEM WILL DO THE SHELL : \033[34m su - postgres -c 'pgpool -n -d -D > /data1/pg_logs/pgpool.log 2>&1 &' \033[0m"
su - postgres -c 'pgpool -n -d -D > /data1/pg_logs/pgpool.log 2>&1 &'
pgport=$(netstat -lntup|egrep '9898|9999'|wc -l)
[ $pgport -gt 0 ] && echo -e "Slave host pgpool is \033[32m RUNNING!!! \033[0m"
exit 0
fi
done