序幕
HAProxy是一个开源软件，可以负载平衡HTTP和TCP服务器。在 上HAProxy的前面的文章中 ，我们配置的负载均衡HTTP和在这其中，我们会为MySQL这样做。 你所有的MySQL服务器必须被配置为执行 主-主复制负载平衡涉及的读取和写入到所有的后端。 本文将使用以下三个Droplet： Droplet 1 - 负载平衡器 主机名：haproxy 操作系统：Ubuntu 私人IP：10.0.0.100 Droplet 2 - 节点1 主机名：mysql-1 操作系统：Debian 7 私人IP：10.0.0.1 Droplet 2 - Node 2 主机名：mysql-2 操作系统：Debian 7 私人IP：10.0.0.2 在继续之前，请确保所有MySQL服务器都已启动，正在运行并正确复制数据库写入。准备MySQL服务器
我们需要通过为HAProxy创建两个额外的用户来准备MySQL服务器。 HAProxy将使用第一个用户来检查服务器的状态。root@mysql-1# mysql -u root -p -e "INSERT INTO mysql.user (Host,User) values ('10.0.0.100','haproxy_check'); FLUSH PRIVILEGES;"
root@mysql-1# mysql -u root -p -e "GRANT ALL PRIVILEGES ON *.* TO 'haproxy_root'@'10.0.0.100' IDENTIFIED BY 'password' WITH GRANT OPTION; FLUSH PRIVILEGES"
安装MySQL客户端
MySQL客户端必须安装在HAProxyDroplet上以测试连接。root@haproxy# apt-get install mysql-client
root@haproxy# mysql -h 10.0.0.1 -u haproxy_root -p -e "SHOW DATABASES"
安装HAProxy
在HAProxy服务器上安装软件包。root@haproxy# apt-get install haproxy
root@haproxy# sed -i "s/ENABLED=0/ENABLED=1/" /etc/default/haproxy
root@haproxy:~# service haproxy
Usage: /etc/init.d/haproxy {start|stop|reload|restart|status}
配置HAProxy
重命名原始配置文件mv /etc/haproxy/haproxy.cfg{,.original}
nano /etc/haproxy/haproxy.cfg
global
log 127.0.0.1 local0 notice
user haproxy
group haproxy
defaults
log global
retries 2
timeout connect 3000
timeout server 5000
timeout client 5000
listen mysql-cluster
bind 127.0.0.1:3306
mode tcp
option mysql-check user haproxy_check
balance roundrobin
server mysql-1 10.0.0.1:3306 check
server mysql-2 10.0.0.2:3306 check
listen 0.0.0.0:8080
mode http
stats enable
stats uri /
stats realm Strictly\ Private
stats auth A_Username:YourPassword
stats auth Another_User:passwd
http://<Public IP of Load Balancer>:8080/
service haproxy start
root@haproxy# mysql -h 127.0.0.1 -u haproxy_root -p -e "SHOW DATABASES"
测试负载平衡和故障转移
要检查是否负载均衡工作查询 SERVER_ID变量的两倍以上。root@haproxy# mysql -h 127.0.0.1 -u haproxy_root -p -e "show variables like 'server_id'"
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| server_id | 1 |
+---------------+-------+
root@haproxy# mysql -h 127.0.0.1 -u haproxy_root -p -e "show variables like 'server_id'"
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| server_id | 2 |
+---------------+-------+
nano /etc/haproxy/haproxy.cfg
server mysql-2 10.0.0.2:3306 check weight 2
service haproxy reload
root@haproxy:~# for i in `seq 1 6`
do
mysql -h 127.0.0.1 -u haproxy_root -ppassword -e "show variables like 'server_id'"
done
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| server_id | 1 |
+---------------+-------+
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| server_id | 2 |
+---------------+-------+
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| server_id | 2 |
+---------------+-------+
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| server_id | 1 |
+---------------+-------+
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| server_id | 2 |
+---------------+-------+
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| server_id | 2 |
+---------------+-------+
root@mysql-1# service mysql stop
root@mysql-1# ifconfig eth1 down
tail /var/log/haproxy/haproxy.log
Nov 15 00:08:51 localhost haproxy[1671]: Server mysql-cluster/mysql-1 is DOWN, reason: Layer4 timeout, check duration: 2002ms. 1 active and 0 backup servers left. 0 sessions active, 0 requeued, 0 remaining in queue.
减少故障转移间隔
当MySQL服务器关闭时HAProxy需要一些时间来检测此故障并将其从集群中删除。在本节中，我们将了解如何控制此时间。首先，我们将看到如何测量这个值。一种方法是使用阻止MySQL的端口 的iptables了一定的时间，然后删除该规则并检查日志。root@mysql-1:~# ifconfig eth1 down &&
date &&
sleep 20 &&
ifconfig eth1 up &&
date
Fri Nov 15 00:37:09 IST 2013
Fri Nov 15 00:37:29 IST 2013
root@haproxy:~# tail /var/log/haproxy.log
Nov 15 16:49:38 localhost haproxy[1275]: Server mysql-cluster/mysql-1 is DOWN, reason: Layer4 connection problem, info: "Connection refused", check duration: 0ms. 1 active and 0 backup servers left. 0 sessions active, 0 requeued, 0 remaining in queue.
Nov 15 16:49:56 localhost haproxy[1275]: Server mysql-cluster/mysql-1 is UP, reason: Layer7 check passed, code: 0, info: "5.5.31-0+wheezy1-log", check duration: 1ms. 2 active and 0 backup servers online. 0 sessions requeued, 0 total in queue.
16:49:32 - Port 3306 on mysql-1 was blocked
16:49:34 - Check - Failed - Failure No. 1
16:49:36 - Check - Failed - Failure No. 2
16:49:38 - Check - Failed - Failure No. 3 (server removed and event logged)
16:49:52 - Firewall rule removed port 3306 accessible
16:49:54 - Check - Passed - Success No. 1
16:49:56 - Check - Passed - Success No. 2 (server added to cluster and event logged)
nano /etc/haproxy/haproxy.cfg
server mysql-1 10.0.0.1:3306 check fall 2 inter 1000
server mysql-2 10.0.0.2:3306 check fall 2 inter 1000
nano /etc/haproxy/haproxy.cfg
server mysql-1 10.0.0.1:3306 check fastinter 1000
server mysql-2 10.0.0.2:3306 check fastinter 1000
root@mysql-1:~# iptables -A INPUT -p tcp --dport 3306 -j REJECT &&
date &&
sleep 20 &&
iptables -D INPUT -p tcp --dport 3306 -j REJECT &&
date
Fri Nov 15 17:18:48 IST 2013
Fri Nov 15 17:19:08 IST 2013
root@haproxy:~# tail /var/log/haproxy.log
Nov 15 17:18:52 localhost haproxy[1353]: Server mysql-cluster/mysql-1 is DOWN, reason: Layer4 connection problem, info: "Connection refused", check duration: 0ms. 1 active and 0 backup servers left. 0 sessions active, 0 requeued, 0 remaining in queue.
Nov 15 17:19:11 localhost haproxy[1353]: Server mysql-cluster/mysql-1 is UP, reason: Layer7 check passed, code: 0, info: "5.5.31-0+wheezy1-log", check duration: 1ms. 2 active and 0 backup servers online. 0 sessions requeued, 0 total in queue.
17:18:48 - Port 3306 blocked
17:18:50 - Check - Failed - Failure No. 1
17:18:51 - Check - Failed - Failure No. 2
17:18:52 - Check - Failed - Failure No. 3 (server removed and event logged)
17:19:08 - Firewall rule removed
17:19:10 - Check - Passed - Success No. 1
17:19:11 - Check - Passed - Success No. 2 (server added to cluster and event logged)
重要
我们做的测试先前被拒绝数据包时，HAProxy的启动通过发送一个SYN包到 mysql-1收到一个RST包（而不是SYN + ACK）的连接，这意味着。这就是为什么日志条目提到“连接被拒绝”。在这种情况下，只有fall，inter和fastinter值进入场景。 相反，如果HAProxy在发送SYN后没有收到任何连接的连接超时。在这种情况下，除了上述参数之外，“超时”持续时间进入场景。这种情况可能发生，如果- iptables的设置为DROP
- 私有接口down
- 私有网络基础设施存在问题
深入阅读
正式文件 http://cbonte.github.io/haproxy-dconv/configuration-1.4.html
：提交
Jesin一
