rewrites-redirects.md

Rewrite

A rewrite changes the URI of a request internally without informing the client (browser). It allows you to modify the request URL on the server-side.

location /blog {
    rewrite ^/blog/(.*)$ /articles/$1 break;    # The (.*) part captures everything after /blog/, and stores it in a variable $1. 
    
    # Without the "()", '.*' will only match but it doesn't capture that part of the string for further use.

}

• If a user requests /blog/post1, Nginx internally rewrites it to /articles/post1, serving content from the /articles/ directory instead.

• break: Stops processing and uses the rewritten URI in the same location block.

last and break flags

In Nginx, the last and break flags are used in rewrite rules to control how Nginx processes the request after applying the rewrite. They determine whether Nginx should continue looking for more matching location blocks or stop further processing. Here’s a simple breakdown:

1. last Flag

• The last flag tells Nginx to stop rewriting the URI and reprocess the request using the newly rewritten URI. Nginx will look for a new matching location block based on the rewritten URI.

Example:

server {
    listen 80;

    location /blog {
        rewrite ^/blog/(.*)$ /articles/$1 last;    
    }

    location /articles {
        root /var/www/mysite;
        index index.html;
    }
}

• Request: http://example.com/blog/post1

• What happens:

  • The URI /blog/post1 is rewritten to /articles/post1 because of the rewrite rule.
  • The last flag tells Nginx to stop rewriting and reprocess the new URI /articles/post1 by searching for a new matching location block.
  • Nginx will now look for the location /articles block to serve the file.

2. break Flag

• The break flag tells Nginx to stop rewriting the URI and process the request using the current location block. It will not look for any new location blocks after the rewrite.

Example:

server {
    listen 80;

    location /blog {
        rewrite ^/blog/(.*)$ /static/$1 break;
        root /var/www/mysite;
    }
}

• Request: http://example.com/blog/image.png

• What happens:

  • The URI /blog/image.png is rewritten to /static/image.png.
  • The break flag tells Nginx to stop processing any further location blocks and serve the file /var/www/mysite/static/image.png from within the same location block.

---

Redirect

A redirect informs the client (browser) that the requested resource has been moved to a new URL. The browser is then redirected to the new URL, either temporarily or permanently.

location /old-page {
    return 302 /new-page;   # temporary redirect (Used for URLs that may change again in the future.)
}

location /new-page {
    ...
}

or,

location /old-page {
    return 302 /new-page;   # permanent redirect
}

location /new-page {
    ...
}