# Directive inheritance in NGINX

Directive inheritance in NGINX is a way of reusing configuration directives in different parts of the NGINX configuration file. Directives are inherited from the parent context to the child context. A context is a block of configuration directives. The main contexts in NGINX are:

* **Global context**: This is the top-level context and applies to the entire NGINX configuration.
    
* **HTTP context**: This context applies to the HTTP protocol.
    
* **Server context**: This context applies to a specific server block.
    
* **Location context**: This context applies to a specific location within a server block.
    

For example, the following configuration defines a global directive `worker_processes` and a server directive `listen`. The `worker_processes` directive is inherited by the `server` context and the `listen` directive is inherited by the `location` context.

```nginx
worker_processes 2;

http {
  server {
    listen 80;

    location / {
    }
  }
}
```

In this configuration, NGINX will create two worker processes and listen on port 80. The `location` context will inherit the `worker_processes` directive from the `http` context and the `listen` directive from the `server` context.

There are a few things to keep in mind about directive inheritance in NGINX:

* Directives can only be inherited from a parent context to a child context.
    
* Directives cannot be inherited from a child context to a parent context.
    
* Directives can be overridden in a child context.
    

For example, the following configuration defines a server directive `listen` in the `http` context and a location directive `listen` in the `location` context. The `listen` directive in the `location` context will override the `listen` directive in the `http` context.

```nginx
http {
  listen 80;

  server {
    listen 8080;

    location / {
      listen 80;
    }
  }
}
```

Here is a breakdown of the configuration:

* The `http` context defines the global settings for the NGINX server. In this case, the `listen` directive tells NGINX to listen on port 80.
    
* The `server` context defines a virtual host. In this case, the `listen` directive tells NGINX to listen on port 8080.
    
* The `location` context defines a location within a virtual host. In this case, the `listen` directive tells NGINX to listen on port 80 for requests to the `/` location.
    

Therefore, NGINX will listen on port 8080 for all requests, except for requests to the `/` location, which will be listened to on port 80.

I hope this explanation of directive inheritance in NGINX is helpful. Please let me know in the comments if you have any other questions.