NGINX Varnish SSL - too many redirects

You need to configure your SSL terminator as reverse proxy:

in your nginx ssl configuration, add this:

location / {
  proxy_pass  http://VARNISH-IP-ADDR-OR-HOSTNAME;
  proxy_set_header Host $host;
  proxy_set_header X-Real-IP $remote_addr;
  proxy_set_header X-Forwarded-For $remote_addr;
  proxy_set_header X-Forwarded-Proto https;
  proxy_set_header X-Nginx on;
  proxy_redirect     off;
}

Then, in your varnish vcl file

if ( req.http.X-Nginx != "on") {
      return (synth(750, ""));
}
...
sub vcl_synth {
  if (resp.status == 750) {
    set resp.status = 301;
    set resp.http.Location = "https://YOUR-SSL-FQDN" + req.url;
    return(deliver);
  }
}

Last: for wordpress, in wp-config.php add these lines:

define('FORCE_SSL_ADMIN', true);
$_SERVER['HTTPS']='on';

NOTE: I'm assuming your other varnish configuration is good and your nginx "8080" configuration is good for your php application.