How to config HAproxy, KeepAlived, Nginx, PHP-FPM

This docs talk about high-availability service by Keepalived, HAproxy define port listen at the front-end and forward request into web server backend.

Topology

       I have a topology include: 

               - Two server running HAproxy, KeepAlived service with a virtual IP address.

               - Two server running Nginx - web server backend.

Server information:

 - HAproxy01: 

          OS:             CentOS 6.8 64bit final.

          IP addr:       192.168.22.54/24

          Port:  TCP 80.

 - HAproxy02:

          OS:              CentOS 6.8 64bit final.

          IP addr:        192.168.22.56/24

          Port:  TCP 80.

Virtual IP addr: 

          192.168.22.55 

           port: TCP 80

 - Webserver01

          OS:               CentOS 6.8 64bit final

          IP addr:         192.168.22.59/24

          Port: TCP:     8080

 - Webserver02

          OS:               CentOS 6.8 64bit final

          IP addr:         192.168.22.60/24

          Port: TCP:     8080

First, i config nginx running for a php site, so i will config php-fpm more. Here is nginx config:

# vi /etx/nginx/nginx.conf

server {

        listen 8080;

        server_name   example-site.org;

        index index.php;

        root /home/nginx/example-site.org;

        access_log off;

        error_log   /var/log/nginx/example-site-error.log error crit;

        

        location ~ \.php$ {

            try_files $uri =404;

            fastcgi_split_path_info ^(.+\.php)(/.+)$;

            fastcgi_pass unix:/var/run/php-fpm/php-fpm.sock;

            fastcgi_index index.php;

            fastcgi_send_timeout 300;

            fastcgi_connect_timeout 300;

            fastcgi_read_timeout 300;

            fastcgi_buffer_size 32k;

            fastcgi_busy_buffers_size 32k;

            fastcgi_buffers 8 16k;

            fastcgi_temp_file_write_size 32k;

            fastcgi_intercept_errors on;

            fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;

            include fastcgi_params;

        }
}

php-fpm config:

# vi /etc/php-fpm.d/www.conf

[www]
listen = /var/run/php-fpm/php-fpm.sock
listen.allowed_clients = 127.0.0.1
listen.owner = nginx
listen.group = nginx
listen.mode = 0660
user = nginx
group = nginx
pm = dynamic
pm.max_children = 13
pm.start_servers = 3
pm.min_spare_servers = 2
pm.max_spare_servers = 6
pm.max_requests = 500
pm.status_path = /php_status
request_terminate_timeout = 120s
request_slowlog_timeout = 4s
slowlog = /home/nginx/logs/php-fpm-slow.log
rlimit_files = 131072
rlimit_core = unlimited
catch_workers_output = yes
env[HOSTNAME] = \$HOSTNAME
env[PATH] = /usr/local/bin:/usr/bin:/bin
env[TMP] = /tmp
env[TMPDIR] = /tmp
env[TEMP] = /tmp
php_admin_value[error_log] = /home/nginx/logs/php-fpm-error.log
php_admin_flag[log_errors] = on
php_value[session.save_handler] = files

php_value[session.save_path] = /var/lib/php/session


Nginx use unix socket in order to improve performance, faster than call IP:port.
Next, i config HAproxy service on the HAPROXY01 and HAPROXY02 in order to forward request from client.

HAproxy config:

defaults

 mode http

 option http-server-close

 timeout client 20s

 timeout server 20s

 timeout connect 4s

frontend ft_app

 bind 192.168.22.54:80 name app

 default_backend bk_app

backend bk_app

 server s1 192.168.22.59:80 check

 server s2 192.168.22.60:80 check backup

Finally, i config KeepAlived service for HA two server running HAproxy. I need a virtual IP address, between two server HAPROXY have channel called "heartbeat" with responsibility communicate servers. And when server HAProxy is down, or service HAproxy stop, it will make HAPROXY02 become MASTER state.

KeepAlived config:

# vi /etc/keepalived/keepalived.conf

vrrp_script chk_nginx {
        script "/usr/local/bin/check_nginx.sh"
        interval 2
        fall 2
        rise 2
}

vrrp_instance VI_1 {
        interface eth0
        state MASTER
        virtual_router_id 51
        priority 101                    # 101 on master, 100 on backup
        nopreempt

        unicast_src_ip 192.168.22.54
        unicast_peer {
                192.168.22.56
        }

        virtual_ipaddress {
            192.168.22.55
        }
        track_script {
            chk_nginx
        }
        notify /usr/local/bin/keepalived.state.sh

}

# vi /usr/local/bin/check_nginx.sh
#!/bin/bash
HAPROXY_STATUS=$(/bin/ps ax | grep -w [n]ginx)
if [ "$NGINX_STATUS" != "" ]
then
  exit 0
else
  logger "Nginx is NOT running. Setting keepalived state to FAULT."
  exit 1
fi


# vi /usr/local/bin/keepalived.state.sh
#!/bin/bash
TYPE=$1
NAME=$2
STATE=$3
echo $STATE > /var/run/keepalived.state


# ip addr show

This command is show server hold virtual ip: 192.168.22.55

If you get error about php-fpm, nginx, maybe you forget set permission for session php, try:

# mkdir -p /var/log/nginx
# chown -R nginx:nginx /var/log/nginx
# chown -R nginx:nginx /var/lib/php/session