# Creating NGINX Plus and NGINX Configuration Files

NGINX and NGINX Plus are similar to other services in that they use a text‑based configuration file written in a particular format. By default the file is named nginx.conf and for NGINX Plus is placed in the /etc/nginx directory. (For open source NGINX, the location depends on the package system used to install NGINX and the operating system. It is typically one of /usr/local/nginx/conf, /etc/nginx, or /usr/local/etc/nginx.)

## Directives

The configuration file consists of directives and their parameters. Simple (single‑line) directives each end with a semicolon. Other directives act as “containers” that group together related directives, enclosing them in curly braces ( {} ); these are often referred to as blocks. Here are some examples of simple directives.

user             nobody;
error_log        logs/error.log notice;
worker_processes 1;


## Feature-Specific Configuration Files

To make the configuration easier to maintain, we recommend that you split it into a set of feature‑specific files stored in the /etc/nginx/conf.d directory and use the include directive in the main nginx.conf file to reference the contents of the feature‑specific files.

include conf.d/http;
include conf.d/stream;
include conf.d/exchange-enhanced;


## Contexts

A few top‑level directives, referred to as contexts, group together the directives that apply to different traffic types:

Directives placed outside of these contexts are said to be in the main context.

### Virtual Servers

In each of the traffic‑handling contexts, you include one or more server blocks to define virtual servers that control the processing of requests. The directives you can include within a server context vary depending on the traffic type.

For HTTP traffic (the http context), each server directive controls the processing of requests for resources at particular domains or IP addresses. One or more location contexts in a server context define how to process specific sets of URIs.

For mail and TCP/UDP traffic (the mail and stream contexts) the server directives each control the processing of traffic arriving at a particular TCP port or UNIX socket.

### Sample Configuration File with Multiple Contexts

The following configuration illustrates the use of contexts.

user nobody; # a directive in the 'main' context

events {
# configuration of connection processing
}

http {
# Configuration specific to HTTP and affecting all virtual servers

server {
# configuration of HTTP virtual server 1
location /one {
# configuration for processing URIs starting with '/one'
}
location /two {
# configuration for processing URIs starting with '/two'
}
}

server {
# configuration of HTTP virtual server 2
}
}

stream {
# Configuration specific to TCP/UDP and affecting all virtual servers
server {
# configuration of TCP virtual server 1
}
}


### Inheritance

In general, a child context – one contained within another context (its parent) – inherits the settings of directives included at the parent level. Some directives can appear in multiple contexts, in which case you can override the setting inherited from the parent by including the directive in the child context. For an example, see the proxy_set_header directive.

For changes to the configuration file to take effect, it must be reloaded. You can either restart the nginx process or send the reload signal to upgrade the configuration without interrupting the processing of current requests. For details, see Controlling NGINX Processes at Runtime.