Introduction to Nginx: Features, Architecture, and Custom Module Development

Nginx (engine x) is a high‑performance web server, reverse proxy, and also an IMAP/POP3/SMTP server. It was started by Russian programmer Igor Sysoev in 2002, quickly becoming the fastest‑growing web server with a market share of about 33.3% and ranking second worldwide.

Community forks:

OpenResty, created by agentzh, adds the ngx_lua module for Lua‑based plugins and bundles many modules and libraries.

Tengine, developed by the Taobao team, incorporates features driven by Taobao’s own business needs.

The official Nginx version, which is updated frequently and offers both free and commercial editions.

Source code structure:

Approximately 110,000 lines of C code.

Key directories: core – core and basic settings. event – event‑driven model and various I/O multiplexing modules. http – HTTP server and modules. mail – mail proxy server and modules. os – operating‑system‑related implementations. misc – miscellaneous utilities.

Nginx characteristics:

Reverse proxy and load balancer.

High reliability with a master‑worker multi‑process model.

Highly extensible and modular.

Non‑blocking, event‑driven architecture.

Low memory consumption and hot deployment capability.

Typical application scenarios:

Static file serving.

Reverse proxy and load balancing.

Security protection.

Intelligent routing (e.g., enterprise‑level gray testing, map POI switching).

Gray releases.

Static content generation.

Message pushing.

Real‑time image compression.

Anti‑hotlinking.

Framework model and process flow:

Master process monitors worker processes, restarts them when they exit, and handles signals.

Worker processes handle client requests and act on signals from the master.

Cache loader process loads cache index files and then exits.

Cache manager process manages disk cache size, deleting least‑used data when limits are exceeded.

Upstream design:

Access to third‑party servers.

Robust underlying HTTP communication.

Asynchronous, non‑blocking operation.

Zero‑copy memory transfer between upstream and downstream.

Support for custom module development.

Custom module development:

Highly abstracted module interfaces offering great flexibility.

Simple configuration module design.

Core module interfaces are streamlined.

Multi‑level, multi‑category module architecture.

Key module types:

Core modules – provide fundamental functionality.

Handler modules – receive client requests and construct response headers and bodies.

Filter modules – process response headers and content after generation but before sending to the client.

Upstream modules – enable Nginx to bypass single‑machine limits, handling asynchronous data reception, processing, and forwarding to backend services.

Load‑balance modules – implement algorithms to select backend servers for request forwarding.

ngx_lua module – embeds Lua scripting with low memory overhead, fast execution, powerful coroutines, non‑blocking I/O, and natural business‑logic expression.

© The content is sourced from the internet; copyright belongs to the original author. If any infringement is identified, please notify us for prompt removal.