CORS nginx config using maps

headers.conf

add_header "Access-Control-Allow-Credentials" $cors_allowed_credentials;
add_header "Access-Control-Allow-Headers" $cors_allowed_headers;
add_header "Access-Control-Allow-Methods" $cors_allowed_methods;
add_header "Access-Control-Allow-Origin" $cors_allowed_origin;
add_header "Access-Control-Max-Age" $cors_max_age;

maps.conf

map $http_origin $cors_is_allowed_origin {
    hostnames;

    default "false";

    "~example(qa|staging)??\.com\.au$" "true";
}
map $request_method $cors_is_allowed_methods {
    default "false";

    OPTIONS "true";
    GET "true";
    POST "true";
    DELETE "true";
    PUT "true";
}

map "$cors_is_allowed_origin:$cors_is_allowed_methods" $cors_is_allowed {
    default "false";

    "true:true" "true";
}

# this is a proxy for the credentials cors header
map $cors_is_allowed $cors_allowed_credentials {
    default "";

    "true" "true";
}

map $cors_is_allowed $cors_allowed_headers {
    default "";

    "true" "origin, x-requested-with, content-type, accept, pragma";
}

map $cors_is_allowed $cors_allowed_methods {
    default "";

    "true" "DELETE, GET, POST, OPTIONS, PUT";
}

map "$request_method:$cors_is_allowed" $cors_max_age {
    default "";

    "OPTIONS:true" "1728000";
}

map $cors_is_allowed $cors_allowed_origin {
    default "";

    "true" $http_origin;
}

nginx.conf

http {
  # all your standard http config here
  # ...
  
  include /etc/nginx/conf.d/maps.conf;

  server {
      listen [::]:80 default_server;
      listen 80 default_server;
      server_name _;
      charset utf-8;

      autoindex off;
      sendfile off;
      rewrite_log on;
      log_not_found on;

      root /var/www/html;
      index index.html;

      include /etc/nginx/conf.d/headers.conf;

      # Handle preflight requests
      if ($request_method = "OPTIONS") {
          return 204;
      }

      # locations go here
      # ...
  }
}

This is a config I came up with for NGINX using maps instead of ifs based on If is Evil. Would love some feedback on whether this is a valid approach or there is a better way to do this?