A simple WebFinger resource for nginx (compatible with draft-ietf-appsawg-webfinger-14.txt).

webfinger.nginx

location ~ /.well-known/webfinger {
    add_header 'Access-Control-Allow-Origin' '*';
    if ($arg_resource = "") {
        return 400;
    }
    try_files /profiles/$arg_resource.json =404;
}

Add application/json json; to /etc/nginx/mime.types to serve the files with the right Content-Type. Optionally, add application/json to charset_types if you want to specify the charset in the Content-Type.

Note that nginx doesn't decode URL parameters, so the file names have to be URL encoded as well: ?resource=acct%3Abob%40example.com will look for a file called /profiles/acct%3Abob%40example.com.json. I suggest symlinks as a workaround to accept unencoded resource parameters.

There is now a dedicated repository for this: https://github.com/agrueneberg/nginx-webfinger Please report issues there.