在流复制主备环境下怎么使用HAProxy搭建负载均衡环境

这篇文章主要介绍"在流复制主备环境下怎么使用HAProxy搭建负载均衡环境"，在日常操作中，相信很多人在在流复制主备环境下怎么使用HAProxy搭建负载均衡环境问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答"在流复制主备环境下怎么使用HAProxy搭建负载均衡环境"的疑惑有所帮助！接下来，请跟着小编一起来学习吧！

安装
使用yum安装相关软件，在数据库服务器上安装xinted和telnet

yum -y install xinetd telnet

配置xinetd
编写识别主从库的脚本pgsqlchk

[pg12@localhost ~]$ cat pgsqlchk #!/bin/bash# This script checks if a postgres server is healthy running on localhost. It will return:# "HTTP/1.x 200 OK\r" (if postgres is running smoothly)# - OR -# "HTTP/1.x 500 Internal Server Error\r" (else)# The purpose of this script is make haproxy capable of monitoring postgres properly# It is recommended that a low-privileged postgres  user is created to be used by this script.# For eg. create  user healthchkusr login password 'hc321';PGBIN=/appdb/pg12/pg12.0/binPGSQL_HOST="localhost"PGSQL_PORT="5432"PGSQL_DATABASE="testdb"PGSQL_USERNAME="pg12"export PGPASSWORD="root"TMP_FILE="/tmp/pgsqlchk.out"ERR_FILE="/tmp/pgsqlchk.err"# We perform a simple query that should return a few resultsVALUE=`$PGBIN/psql -qt -h localhost -U pg12 -p 5432 -c "select pg_is_in_recovery()" 2> /dev/null`# Check the output. If it is not empty then everything is fine and we return something. Else, we just do not return anything.if [ $VALUE == "t" ]then    /bin/echo -e "HTTP/1.1 206 OK\r\n"    /bin/echo -e "Content-Type: Content-Type: text/plain\r\n"    /bin/echo -e "\r\n"    /bin/echo "Standby"    /bin/echo -e "\r\n"elif [ $VALUE == "f" ]then    /bin/echo -e "HTTP/1.1 200 OK\r\n"    /bin/echo -e "Content-Type: Content-Type: text/plain\r\n"    /bin/echo -e "\r\n"    /bin/echo "Primary"    /bin/echo -e "\r\n"else    /bin/echo -e "HTTP/1.1 503 Service Unavailable\r\n"    /bin/echo -e "Content-Type: Content-Type: text/plain\r\n"    /bin/echo -e "\r\n"    /bin/echo "DB Down"    /bin/echo -e "\r\n"fi[pg12@localhost ~]$

如为主库，该脚本模拟接收http请求返回http 200响应，如为从库则返回206，如数据库不可用则返回503

#主库[pg12@localhost ~]$ ifconfig | grep 'inet'        inet 192.168.26.28  netmask 255.255.0.0  broadcast 192.168.255.255        ...[pg12@localhost ~]$ ./pgsqlchk HTTP/1.1 200 OKContent-Type: Content-Type: text/plainPrimary#从库[pg12@localhost ~]$ ifconfig | grep 'inet'        inet 192.168.26.25  netmask 255.255.0.0  broadcast 192.168.255.255        ...[pg12@localhost ~]$ ./pgsqlchk HTTP/1.1 206 OKContent-Type: Content-Type: text/plainStandby

创建xinetd配置文件，端口使用23267，指向刚才配置的pgsqlchk执行文件

[pg12@localhost ~]$ cat /etc/xinetd.d/pgsqlchkservice pgsqlchk{        flags           = REUSE        socket_type     = stream        port            = 23267        wait            = no        user            = nobody        server          = /home/pg12/pgsqlchk        log_on_failure  += USERID        disable         = no        only_from       = 0.0.0.0/0        per_source      = UNLIMITED}

添加服务，并启动xinetd

[pg12@localhost ~]$ sudo bash -c 'echo "pgsqlchk 23267/tcp # pgsqlchk" >> /etc/services'[pg12@localhost ~]$ sudo systemctl start xinetd[pg12@localhost ~]$ systemctl status xinetd● xinetd.service - Xinetd A Powerful Replacement For Inetd   Loaded: loaded (/usr/lib/systemd/system/xinetd.service; enabled; vendor preset: enabled)   Active: active (running) since Thu 2019-11-14 12:04:37 CST; 23s ago  Process: 2847 ExecStart=/usr/sbin/xinetd -stayalive -pidfile /var/run/xinetd.pid $EXTRAOPTIONS (code=exited, status=0/SUCCESS) Main PID: 2848 (xinetd)   CGroup: /system.slice/xinetd.service           └─2848 /usr/sbin/xinetd -stayalive -pidfile /var/run/xinetd.pid[pg12@localhost ~]$

检查服务和监听，（可通过设置flags=IPv4调整为监听IPv4地址）

[pg12@localhost ~]$ sudo netstat -antup | grep 23267tcp6       0      0 :::23267                :::*                    LISTEN      6837/xinetd[pg12@localhost ~]$ sudo systemctl restart xinetd[pg12@localhost ~]$ sudo systemctl status xinetd -l● xinetd.service - Xinetd A Powerful Replacement For Inetd   Loaded: loaded (/usr/lib/systemd/system/xinetd.service; enabled; vendor preset: enabled)   Active: active (running) since Thu 2019-11-14 15:43:49 CST; 6s ago  Process: 7461 ExecStart=/usr/sbin/xinetd -stayalive -pidfile /var/run/xinetd.pid $EXTRAOPTIONS (code=exited, status=0/SUCCESS) Main PID: 7462 (xinetd)   CGroup: /system.slice/xinetd.service           └─7462 /usr/sbin/xinetd -stayalive -pidfile /var/run/xinetd.pidNov 14 15:43:49 localhost.localdomain xinetd[7462]: START: pgsqlchk pid=7463 from=192.168.26.26Nov 14 15:43:49 localhost.localdomain xinetd[7462]: EXIT: pgsqlchk status=0 pid=7463 duration=0(sec)Nov 14 15:43:52 localhost.localdomain xinetd[7462]: START: pgsqlchk pid=7465 from=192.168.26.26Nov 14 15:43:52 localhost.localdomain xinetd[7462]: EXIT: pgsqlchk status=0 pid=7465 duration=0(sec)Nov 14 15:43:52 localhost.localdomain xinetd[7462]: START: pgsqlchk pid=7466 from=192.168.26.26Nov 14 15:43:52 localhost.localdomain xinetd[7462]: EXIT: pgsqlchk status=0 pid=7466 duration=0(sec)Nov 14 15:43:55 localhost.localdomain xinetd[7462]: START: pgsqlchk pid=7467 from=192.168.26.26Nov 14 15:43:55 localhost.localdomain xinetd[7462]: EXIT: pgsqlchk status=0 pid=7467 duration=0(sec)Nov 14 15:43:55 localhost.localdomain xinetd[7462]: START: pgsqlchk pid=7468 from=192.168.26.26Nov 14 15:43:55 localhost.localdomain xinetd[7462]: EXIT: pgsqlchk status=0 pid=7468 duration=0(sec)[pg12@localhost ~]$ sudo netstat -antup | grep 23267tcp        0      0 0.0.0.0:23267           0.0.0.0:*               LISTEN      7462/xinetd         [pg12@localhost ~]$

配置HAProxy with xinetd
在代理服务器上安装HAProxy

yum -y install haproxy telnet

配置HAProxy（/etc/haproxy/haproxy.cfg）

[pg12@localhost ~]$ cat /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 http-server-close    option forwardfor       except 127.0.0.0/8    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                 3000listen stats    mode http    bind *:7000    stats enable    stats uri /listen ReadWrite    bind *:5000    option httpchk    http-check expect status 200    default-server inter 3s fall 3 rise 2 on-marked-down shutdown-sessions    server pg0 pg0:5432 maxconn 100 check port 23267listen ReadOnly    bind *:5001    option httpchk    http-check expect status 206    default-server inter 3s fall 3 rise 2 on-marked-down shutdown-sessions    server pg0 pg0:5432 maxconn 100 check port 23267    server pg1 pg1:5432 maxconn 100 check port 23267[pg12@localhost ~]$

启动HAProxy

[pg12@localhost ~]$ sudo systemctl start haproxy[pg12@localhost ~]$

划重点：
1.HAProxy使用TCP模式而不是默认的http模式
2.HAProxy监听的端口是5000-5001
3.端口5000用于RW而5001用于Read-only
4.使用http-check（端口为23267）判断状态
5.pg0可用于读写，pg1仅用于读
6.基于http-check，确定服务器状态（根据服务响应确定：200/206/503）

验证haproxy服务是否正常启动，如出现bind socket的错误，则需调整内核参数和SELinux策略

1.设置内核参数：net.ipv4.ip_nonlocal_bind=12.设置SELinux策略setsebool -P haproxy_connect_any=1vim /etc/sysconfig/selinuxSELINUX=enforcing-->SELINUX=permissive

正常启动HAProxy的日志

[root@localhost ~]# systemctl status haproxy -l● haproxy.service - HAProxy Load Balancer   Loaded: loaded (/usr/lib/systemd/system/haproxy.service; disabled; vendor preset: disabled)   Active: active (running) since Thu 2019-11-14 14:41:09 CST; 12min ago Main PID: 1963 (haproxy-systemd)   CGroup: /system.slice/haproxy.service           ├─1963 /usr/sbin/haproxy-systemd-wrapper -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid           ├─1964 /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -Ds           └─1965 /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -DsNov 14 14:41:09 localhost.localdomain systemd[1]: Started HAProxy Load Balancer.Nov 14 14:41:09 localhost.localdomain haproxy-systemd-wrapper[1963]: haproxy-systemd-wrapper: executing /usr/sbin/haproxy -f /etc/haproxy/haproxy.cfg -p /run/haproxy.pid -Ds[root@localhost ~]#

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