domain.com to www.domain.com rewrite in Varnish

Question

I need to rewrite domain.com to www.domain.com using varnish. I have already done that for Nginx. But no Idea how to do in varnish.

Let me explain why I want to do that, if my approach is wrong then please correct me. Whenever I hit the site with domain.com I have a cookie with path .domain.com. Whenever I hit the path with www.domain.com it creates a new cookie with path .www.domain.com Now these two cookies for same user is creating session issues.

I am hoping that if my servers only receive request like www.domain.com then there will be no scope of cookie associated with domain.com

So Ideally, Question is, is rewrite a good approach ? If yes then how to do that with varnish, I have already tried with Nginx but no luck.

Any guidance is deeply appreciated. Thanks guys.

Answer 1

Answering the "rewrite" part (please see the comments as that could be easier), you have 2 options:

1. Perform a client redirect (preferred IMHO) [a]
2. Rewrite the host internally [b]

See also:

• https://www.varnish-software.com/static/book/build/exercises/complete-rewrite_urls_and_headers.html?highlight=redirect
• https://www.varnish-cache.org/trac/wiki/RedirectsAndRewrites
• https://www.varnish-cache.org/trac/wiki/VCLExampleRedirectInVCL

[a]

sub vcl_recv {
  // ...
  if ( req.http.host == "domain.com" ) {
    error 750 "http://www." + req.http.host + req.url;
  }
  // ...
}

sub vcl_error {
  // ...
  if (obj.status == 750) {
    set obj.http.Location = obj.response;
    # Set HTTP 301 for permanent redirect
    set obj.status = 301;
    return(deliver);
  }
  // ...
}

[b]

sub vcl_recv {
  // ...
  if ( req.http.host == "domain.com" ) {
    set req.http.host = "http://www." + req.http.host;
  }
  // ...
}