URL Rewriting

[Alex Harrington]

Hi all

I have a webserver over which I have no control. It's a managed CMS
solution running Apache, however the vendor will not allow us to add URL
rewriting rules or virtual hosts to the configuration.

It serves different websites at the following URLs:

http://example.com
http://example.com/dlc
http://example.com/wyc

I'm hoping I can use Varnish to sit between the web server and my users
to disguise the subfolders in to separate domains - eg

Client URL => Backend URL
http://example.com => http://example.com
http://example.com/index.phtml?d=12345 =>
http://10.108.1.59/index.phtml?d=12345

http://www.deansleisurecentre.com => http://10.108.1.59/dlc
http://www.deansleisurecentre.com/index.phtml?d=12121 =>
http://10.108.1.59/index.phtml?d=12121

http://www.woodingdeanyc.org.uk => http://10.108.1.59/wyc
http://www.woodingdeanyc.org.uk/index.phtml?d=54321 =>
http://10.108.1.59/index.phtml?d=54321

DNS for deansleisurecentre.com and woodingdeanyc.org.uk would point to
the server running Varnish on port 80. The client should not see the
redirect to /dlc or /wyc (ie so that it thinks it's looking at the root
of the domain). Once the client has connected, /dlc is redirected by the
CMS to a url like /index.phtml?d=12345 and all subsequent pages use that
format. The CMS will be happy with
deansleisurecentre.com/index.phtml?d=12345.

I've setup a Debian box using testing and installed the varnish package
1.1.2.

Here is my current config:

default.vcl

backend default {
	set backend.host = "10.108.1.59";
	set backend.port = "80";
}

sub vcl_recv {
	if (req.http.host ~ "^(www.)?deansleisurecentre.com") {
		set req.http.host = "deansleisurecentre.com";
		set req.http.url = regsub(req.url, "^/$", "/dlc");
	}

	if (req.request != "GET" && req.request != "HEAD") {
		pipe;
	}

	if (req.http.Expect) {
		pipe;
	}

	if (req.http.Authenticate || req.http.Cookie) {
		pass;
	}
	lookup;
}

I've edited my local PCs hosts file to point deansleisurecentre.com to
the box running Varnish, however when I access deansleisurecentre.com, I
get http://example.com instead without the rewrite.

Looking at the logs, it appears Varnish is doing the rewrite in the
headers correctly, but the RxURL and TxURL fields always match - surely
shouldn't the TxURL change to match the URL shown in the header (which
selectively includes my URL rewrite?).

I saw an example using berew.http.url however I can only seem to get
that to work in vcl_hit subroutine (currently commented out in my
config) and it seems to make no difference when used.

Can Varnish do what I want, and if so, does anyone have a pointer that
would help me track down the right config?!

Thanks

Alex

-- 
Alex Harrington - Network Manager, Longhill High School

t: 01273 304086 | e: alex at longhill.org.uk