High availability solutions and precautions for building web servers on CentOS

High availability solutions and precautions for building web servers on CentOS

Abstract: In today's Internet era, high availability is based on the stability and reliability of the website. This article will introduce how to build a high-availability web server on CentOS, and attach code examples to help readers better understand and apply it.

Keywords: CentOS, web server, high availability, solutions, precautions

1. Introduction
With the rapid development of the Internet, the number of website users and visits continues to increase. Higher requirements have been put forward for the high availability and reliability of web servers. Here, we will use CentOS to build a high-availability web server and share some precautions to help readers better apply this solution.

2. Build a high-availability web server

1. Install the CentOS operating system
   First, we need to install the CentOS operating system on the server. You can choose the latest version of CentOS distribution and install it according to the guidelines of the official documentation.
2. Configure the network
   After the installation is completed, you need to set the network configuration to ensure that the server can access the Internet normally. In CentOS, network parameters can be set by editing the /etc/sysconfig/network-scripts/ifcfg-eth0 configuration file. For example:

DEVICE=eth0
ONBOOT=yes
BOOTPROTO=static
IPADDR=192.168.0.10
NETMASK=255.255.255.0
GATEWAY=192.168.0.1

3. Install Nginx
   Nginx is a high-performance HTTP and reverse proxy server with good scalability and high availability. We can use the yum command to install Nginx:

yum install nginx

After the installation is complete, you can start and stop the Nginx service through the systemctl command:

systemctl start nginx
systemctl stop nginx

4. Configure Nginx reverse proxy
   In order to achieve high availability, we need to configure Nginx as a reverse proxy server to forward requests to multiple actual running web servers. It can be configured by editing the /etc/nginx/nginx.conf file. An example is as follows:

http {
upstream backend {

server 192.168.0.11:80;
server 192.168.0.12:80;

}

server {

listen 80;
location / {
    proxy_pass http://backend;
}

}
}

The above configuration will forward the request to the web servers on 192.168.0.11 and 192.168.0.12 through Nginx.

5. Install and configure Keepalived
   Keepalived is a software used to achieve high availability and load balancing of servers. We can use the yum command to install Keepalived:

yum install keepalived

After the installation is complete, you need to edit the /etc/keepalived/keepalived.conf configuration file and set the Virtual IP (VIP ) as well as monitoring and failover related parameters. The example is as follows:

vrrp_script chk_nginx {

script "/usr/bin/pgrep nginx"
interval 2
weight -15

}

vrrp_instance VI_1 {

state BACKUP
interface eth0
virtual_router_id 51
priority 100
advert_int 1
authentication {
    auth_type PASS
    auth_pass 123456
}
virtual_ipaddress {
    192.168.0.100
}
track_script {
    chk_nginx
}

}

The above configuration will monitor the Nginx process Whether it is alive or not, if an Nginx process failure is detected, the VIP will be transferred to the backup server.

6. Start Keepalived
   After editing the configuration file, you can use the systemctl command to start and stop the Keepalived service:

systemctl start keepalived
systemctl stop keepalived

Now, you have successfully set up a high-availability web server. When the main server fails, Keepalived will transfer VIPs to the backup server to ensure the normal operation of the website.

3. Notes

1. Backup and recovery
   Back up the website regularly and ensure the integrity and reliability of the backup data. In the event of a failure, website data can be quickly restored.
2. Security and Protection
   Implement effective security measures, including firewalls, intrusion detection and DDoS protection, to ensure the security of the website and server.
3. Monitoring and Logging
   Configure monitoring tools to detect and resolve server failures in a timely manner. At the same time, log recording and analysis are properly arranged to help troubleshoot faults and optimize server performance.

Conclusion:
Through the introduction and examples of this article, you have learned how to build a high-availability web server on CentOS and learned some related precautions. The establishment of high availability is based on stability and reliability. Only through continuous learning and practice can the normal operation of the website be better ensured. I hope this article will help you when building a high-availability web server!

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