Master Nginx: Reverse Proxy, Load Balancing, and High‑Availability Made Simple

What Is Nginx?

Nginx is a high‑performance HTTP and reverse‑proxy server known for low memory usage and strong concurrency; reports show it can handle up to 50,000 concurrent connections.

Nginx Knowledge Map

01 Reverse Proxy

Forward Proxy

In a LAN, a client cannot directly access the Internet and must go through a forward proxy server.

Reverse Proxy

The client is unaware of the proxy; it sends requests to the reverse‑proxy server, which selects a target server, fetches the data, and returns it to the client.

Thus the external address is the proxy’s IP, hiding the real server IP.

02 Load Balancing

When request volume and data grow, a single server cannot meet demand. Adding more servers and distributing requests across them is called load balancing.

Typical request flow: client → Nginx → (optional) database → response.

Example: 15 requests are evenly split among three servers, each handling 5 requests.

03 Static‑Dynamic Separation

To speed up page parsing, static pages are served by one server and dynamic pages by another, reducing load on a single machine.

After separation, static files are handled independently from dynamic content.

04 Nginx Installation on Linux

Download and extract Nginx, then compile and install. (Specific steps omitted for brevity.)

Common Nginx Commands

./nginx -v

./nginx

./nginx -s stop

./nginx -s quit

./nginx -s reload

Configuration File Structure

The main configuration consists of three blocks:

① Global Block

Settings that affect the whole Nginx server (e.g., worker_processes, events).

② Events Block

Controls network connection handling, such as connection serialization and maximum connections.

③ HTTP Block

Contains directives for reverse proxy, load balancing, etc.

location [ = | ~ | ~* | ^~ ] url { ... }

= : exact match, stop searching.

~ : regex match, case‑sensitive.

~* : regex match, case‑insensitive.

^~ : highest‑priority prefix match, stop further regex checks.

05 Reverse Proxy Practical Example

Goal: Access

www.123.com

and have it forward to a Tomcat server on Linux.

Configure two Tomcat instances (ports 8080 and 8081). Nginx listens on port 80 and proxies to the appropriate Tomcat based on URL path.

After configuration, accessing

www.123.com

resolves to the server IP via the host file and is proxied to

localhost:8080

.

Another example routes

http://192.168.25.132:9001/edu/

to

192.168.25.132:8080

and

/vod/

to

192.168.25.132:8081

using regex location blocks.

Target 1:

http://192.168.25.132:9001/edu/ → 192.168.25.132:8080

Target 2:

http://192.168.25.132:9001/vod/ → 192.168.25.132:8081

06 Load Balancing Practical Example

Modify

nginx.conf

to define an upstream group and use the

proxy_pass

directive.

./nginx -s reload

Load‑balancing methods include round‑robin (default), weight, fair, and ip_hash.

Round‑robin: distribute requests evenly.

Weight: higher weight gets more requests.

Fair: based on backend response time.

ip_hash: same client IP always goes to the same backend (helps with session persistence).

07 Static‑Dynamic Separation Practical Example

Configure Nginx to serve static files directly while forwarding dynamic requests to Tomcat.

After setup, static assets are delivered by Nginx, reducing load on the application server.

08 High‑Availability with Keepalived

Deploy two Nginx nodes and install Keepalived to provide a virtual IP. The master node runs Keepalived in MASTER state; the backup runs in BACKUP state. If the master fails, the virtual IP moves to the backup.

# yum install keepalived -y

# systemctl start keepalived.service

Sample

keepalived.conf

(virtual IP 192.168.25.50):

global_defs {

notification_email {

[email protected]

[email protected]

[email protected]

}

notification_email_from [email protected]

smtp_server 192.168.25.147

router_id LVS_DEVEL

}

vrrp_script chk_nginx {

script "/usr/local/src/nginx_check.sh"

interval 2

weight 2

}

vrrp_instance VI_1 {

state BACKUP

interface ens33

virtual_router_id 51

priority 90

advert_int 1

authentication {

auth_type PASS

auth_pass 1111

}

virtual_ipaddress {

192.168.25.50

}

}

After starting Keepalived, the virtual IP can be accessed even if the primary Nginx node goes down.

09 Principle Analysis

Nginx runs a master process that manages multiple worker processes (usually one per CPU core). Workers handle client connections independently; if one worker crashes, others continue serving.

Workers accept connections, parse requests, and forward them to upstream servers or serve static content.

Conclusion

For optimal performance, set the number of workers equal to the CPU count; multiple workers enable hot reloads, and the master‑worker architecture ensures high reliability.