Bài: Thiết lập HAPRoxy - Cân Bằng Tải MySQL 8 Group Replication

Mục tiêu
 + Cài đặt chương trình HAProxy từ mã nguồn
 + Thiết lập system services HAProxy Server 
 + Thiết lập cân bằng tải cho MySQL Group Replication

1. Cài đặt chương trình HAProxy từ mã nguồn

- Kích hoạt PowerTools repo có sẵn ở trong CentOS 8

[root@ha ~]# dnf config-manager --enable PowerTools
[root@ha ~]# dnf makecache
[root@ha ~]# dnf install gcc openssl-devel readline-devel systemd-devel make pcre-devel tar lua lua-devel wget
[root@ha ~]# wget https://www.haproxy.org/download/2.2/src/devel/haproxy-2.2-dev10.tar.gz
[root@ha ~]# tar xvf haproxy-2.2-dev10.tar.gz

[root@ha ~]# cd haproxy-2.2-dev10
[root@ha haproxy-2.2-dev10]# make USE_NS=1 USE_TFO=1 USE_OPENSSL=1 USE_ZLIB=1 USE_LUA=1 USE_PCRE=1 USE_SYSTEMD=1 USE_LIBCRYPT=1 USE_THREAD=1 TARGET=linux-glibc

[root@ha haproxy-2.2-dev10]# make PREFIX=/opt/haproxy-2.2-dev10 install

Mô tả thông số
 + USE_NS: Enable Linux namespace support.
 + USE_TFO: Enable TCP Fast Open. Kernel must be >= 3.7.
 + USE_OPENSSL: Self-explanatory.
 + USE_ZLIB: Use Zlib compression library.
 + USE_LUA: Self-explanatory.
 + USE_PCRE: Enable regex pattern library.
 + USE_SYSTEMD: Enable HAProxy's native systemd support.
 + USE_LIBCRYPT: Enable HAProxy to use encrypted passwords and hashes using the crypt(3) function.
 + USE_THREAD: Enable HAProxy to use multithreading model.
 + TARGET: Self-explanatory.

- Tạo tài khoản dịch vụ

[root@ha ~]# groupadd haproxy
[root@ha ~]# useradd -g haproxy -d /var/lib/haproxy -s /sbin/nologin -c haproxy haproxy


2. Thiết lập System Services HAProxy Server

- Tạo file haproxy-2.2-dev10.service để start/stop/restart dịch vụ HAPROXY

[root@ha ~]# vim /etc/systemd/system/haproxy-2.2-dev10.service

[Unit]
Description=HAProxy 2.2 Dev 10
After=syslog.target network.target

[Service]
Type=notify
EnvironmentFile=/etc/sysconfig/haproxy-2.2-dev10.service
ExecStart=/opt/haproxy-2.2-dev10/sbin/haproxy -f $CONFIG_FILE -p $PID_FILE $CLI_OPTIONS
ExecReload=/bin/kill -USR2 $MAINPID
ExecStop=/bin/kill -USR1 $MAINPID

[Install]
WantedBy=multi-user.target


- Đối với CentOS 8 ta cần phải tạo thêm file "/etc/sysconfig/haproxy-2.2-dev10.service" được tham chiếu từ file "/etc/systemd/system/haproxy-2.2-dev10.service"

[root@ha ~]# vim /etc/sysconfig/haproxy-2.2-dev10.service
#Command line options to pass to HAProxy at startup
#The default is:
#CLI_OPTIONS="-Ws"
CLI_OPTIONS="-Ws"
# Specify an alternate configuration file. The default is:
#CONFIG_FILE=/etc/haproxy/haproxy-2.2-dev10.conf
CONFIG_FILE=/etc/haproxy/haproxy-2.2-dev10.conf
# File used to track process IDs. The default is:
#PID_FILE=/var/run/haproxy-2.2-dev10.pid
PID_FILE=/var/run/haproxy-2.2-dev10.pid

[root@ha ~]# systemctl daemon-reload
[root@ha ~]# mkdir /etc/haproxy
[root@ha ~]# vim /etc/haproxy/haproxy-2.2-dev10.conf
global
    daemon
    maxconn 256
    user        haproxy
    group       haproxy
    chroot      /var/lib/haproxy

#Frontend mysql_cluster_frontend
frontend mysql_cluster_frontend
    bind *:3306
    mode tcp
    option tcplog
    default_backend mysql_cluster_backend

#Backend mysql_cluster_backend
backend mysql_cluster_backend
    mode tcp
    option tcpka
    balance leastconn
    server mysql-01 192.168.255.170:3306 check weight 1 maxconn 180
    server mysql-02 192.168.255.171:3306 check weight 1 maxconn 180
    

Explanation:
balance: This defines the destination selection policy used to select a server to route the incoming connections to.
mode tcp: Galera Cluster uses TCP type of connections.
option tcpka: Enables the keepalive function to maintain TCP connections.
server <server-name> <IP_address> check weight 1 – Defines the nodes you want HAProxy to use in routing connections.

[root@ha ~]# systemctl restart haproxy-2.2-dev10
[root@ha ~]# systemctl stop haproxy-2.2-dev10
[root@ha ~]# systemctl start haproxy-2.2-dev10

[root@ha ~]# netstat -ltunp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      36444/sshd
tcp        0      0 0.0.0.0:3306            0.0.0.0:*               LISTEN      108865/haproxy
tcp6       0      0 :::22                   :::*                    LISTEN      36444/sshd
tcp6       0      0 :::9090                 :::*                    LISTEN      1/systemd
udp        0      0 127.0.0.1:323           0.0.0.0:*                           1207/chronyd
udp6       0      0 ::1:323                 :::*                                1207/chronyd
[root@ha ~]#