HAProxy : HTTP Load Balancing2024/05/28

Install HAProxy to configure Load Balancing Server.
This example is based on the environment like follows.

-----------+---------------------------+--------------------------+------------
           |                           |                          |
           |10.0.0.30                  |10.0.0.51                 |10.0.0.52
+----------+-----------+   +-----------+----------+   +-----------+----------+
|   [ dlp.srv.world ]  |   | [ node01.srv.world ] |   | [ node02.srv.world ] |
|        HAProxy       |   |      Web Server#1    |   |      Web Server#2    |
+----------------------+   +----------------------+   +----------------------+

	Configure Servers that HTTP connection to HAProxy Server is forwarded to backend Web Servers.
[1]	Install HAProxy.

root@dlp:~#

apt -y install haproxy

[2]	Configure HAProxy.

root@dlp:~#

vi /etc/haproxy/haproxy.cfg

# add to last line
# define frontend ( any name is OK for [http-in] )
frontend http-in
        # listen on 80 port
        bind *:80
        # set default backend
        default_backend    backend_servers
        # send X-Forwarded-For header
        option             forwardfor

# define backend
backend backend_servers
        # balance with roundrobin
        balance            roundrobin
        # define backend servers
        server             node01 10.0.0.51:80 check
        server             node02 10.0.0.52:80 check

root@dlp:~#

systemctl reload haproxy

[3]	Change settings on backend Web servers to logging X-Forwarded-For header. Follows are for the case of Apache2 settings, if you use Nginx, refer to here of [3].

root@node01:~#

a2enmod remoteip

Enabling module remoteip.
To activate the new configuration, you need to run:
  service apache2 restart

root@node01:~#

vi /etc/apache2/apache2.conf

# line 212-215 : change like follows
# for RemoteIPInternalProxym, specify HAProxy IP address

RemoteIPHeader X-Forwarded-For
RemoteIPInternalProxy 10.0.0.30
LogFormat "%v:%p %a %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" vhost_combined
LogFormat "%a %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" combined
LogFormat "%a %l %u %t \"%r\" %>s %O" common

root@node01:~#

systemctl reload apache2

[4]	Verify working normally to access to the frontend HAproxy Server.

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