Varnish: Easily redirect "olddomain.com/..." to "newdomain.com/..." URLs at the cache level.

Varnish Redirect Old URLs To New Domain

# Redirect "olddomain.com/..." to "newdomain.com/..." URLs at the cache level.
# Just set an error code (in our case 750) in vcl_recv when accessing old urls, then define the redirect in vcl_error.
# Tested with Varnish 3.X

sub vcl_recv {
  # Set error code when accessing an old url.
  if (req.http.host ~ "^(www\.)?olddomain\.com$") {
    error 750;
  }
}

sub vcl_error {
  if (obj.status == 750) {
    set obj.http.Location = "http://www.newdomain.com" + req.url;
    set obj.status = 302;
    return(deliver);
  }
}