Nginx - Wordpress in a Sub-directory

The following serves the html root folder (/var/www/html) to the domain subdirectory (example.com/wordpress).

Tested on Ubuntu 18.04, PHP 7.3 & latest nginx.

location ^~ /wordpress {
        # Sets /var/www/html as root of example.com/wordpress
        alias /var/www/html;
        # Get script /var/www/html/index.php
        # It's important to start with a slash "/", 
        # that way it looks for index.php at the root directory, 
        # not in example.com/wordpress/some-slug/index.php
        index /index.php;

        # Add a trailing slash if missing
        if (!-f $request_filename) {
            rewrite [^/]$ $uri/ permanent;
        }

        # First attempt to serve request as file, then
        # as directory, then fall back to index.php
        try_files $uri $uri/ /index.php?$args;
}

# For security reasons, set php settings at root level. 
# This prevents root level php files from showing as plain text.
location ~ \.php$ {
        try_files $uri =404;
        fastcgi_split_path_info ^(.+\.php)(/.+)$;

        fastcgi_index index.php;
        # Change this to your fpm socket
        fastcgi_pass php:9000;

        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_param PATH_INFO $fastcgi_path_info;
        include fastcgi_params;
}

Ignore the top answer, it doesn’t work with /wp-login.php.

Here’s a better approach

location / {
        rewrite ^ /wordpress/ permanent;
}

location ^~ /wordpress {
        # Sets /var/www/html as root of example.com/wordpress
        alias /var/www/html;

        # Add a trailing slash if missing
        if (!-f $request_filename) {
            rewrite [^/]$ $uri/ permanent;
        }

        # First attempt to serve request as file, then
        # as directory, then fall back to index.php
        try_files $uri $uri/ /index.php?$args;

        # For security reasons, set php settings at root level. 
        # This prevents root level php files from showing as plain text.
        location ~ \.php$ {
                try_files $uri =404;
                fastcgi_split_path_info ^/wordpress(/.+\.php)(.*)$;

                fastcgi_index index.php;
                # Change this to your fpm socket
                fastcgi_pass php:9000;

                fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
                fastcgi_param PATH_INFO $fastcgi_path_info;
                include fastcgi_params;
        }
}

You can do the below for WP in a sub-folder:

        location /wordpress {
                rewrite ^(/[^/]+)?(/wp-.*) /wordpress/$2 break;
                rewrite ^/wordpress/(.*)$ /wordpress/index.php?q=$1 last;
        }