Directives vs Blocks

NGINX configuration is built from directives. Some directives are simple (single-line), while others are block directives that contain nested directives.

A directive is a single configuration instruction that:

• One line
• Ends with a semicolon (;)
• Does not contain other directives
• Executes a specific action
• Valid only in certain contexts

Syntax

directive_name value1 value2 ...;

Common Core Directives

Directive	Description
worker_processes	Number of worker processes
user	User running workers
listen	Port/IP
server_name	Domain
root	Document root
index	Default file
error_log	Error log path

Global Directive

worker_processes auto;

• worker_processes is a simple directive
• auto tells NGINX to detect CPU cores
• Valid in main context only

Server Directive

server_name example.com www.example.com;

• Defines which domains this server block handles
• Ends with ;
• Valid inside server context

Block Directives (Context Blocks)

A block directive:

• Contains curly braces {}
• Can include other directives
• Creates a configuration context

block_name {
    directive1 value;
    directive2 value;
}

Characteristics

• Defines scope and hierarchy
• Contains nested directives
• Does not end with ;
• Controls inheritance behavior

Common Block Directives

Block	Purpose
events	Connection handling
http	Web configuration
server	Virtual host
location	URI matching
upstream	Backend servers

HTTP Block

http {
    sendfile on;
    keepalive_timeout 65;
}

• http is a block directive
• Applies settings to all HTTP traffic
• Contains multiple simple directives

Server Block

server {
    listen 80;
    server_name example.com;
}

• Defines a virtual host
• Contains multiple simple directives
• No semicolon after closing brace

Key Differences

Feature	Directive	Block
Ends with semicolon	✅ Yes	❌ No
Contains sub-directives	❌ No	✅ Yes
Defines context	❌ No	✅ Yes
Can be nested	❌ No	✅ Yes
Example	listen 80;	server {}

How NGINX Processes Them Together

NGINX reads configuration top-down, building a hierarchical tree of blocks and directives.

http {
    server {
        location / {
            root /var/www/html;
        }
    }
}

• http block applies to all HTTP requests
• server block matches domain/IP
• location block matches URI
• root directive executes

Inheritance & Override Behavior

Directives inside blocks can:

• Inherit values from parent blocks
• Override parent values

http {
    root /var/www/default;

    server {
        root /var/www/example;

        location /images/ {
            root /var/www/assets;
        }
    }
}

Context	Root Used
/index.html	/var/www/example
/images/logo.png	/var/www/assets