Re: balance round-robin/sticky on Host: header

From: Willy Tarreau <>
Date: Wed, 16 Apr 2008 19:38:33 +0200

Hi Jeff,

On Wed, Apr 16, 2008 at 08:52:13AM -0600, Jeff Simpson wrote:
> I tried sending this earlier, so I apologize if it's a duplicate, but I
> never saw it post to the list...

It made it to the list.

> -----------------
> I'm trying to come up with a configuration for HAProxy to balance by the
> 'Host' header in a generic fashion (i.e. one that does not require me to
> hard code host header values to backends). We're using wildcard DNS and
> basically have clients registered to their own host/domain: e.g. -
>,, etc.
> All requests for a particular host would stick to the same server. I
> think it's pretty similar to the URI hashing scheme. If I understand
> that scheme requests are balanced round-robin, but stick to backends
> based on a hash of the uri.
> Any ideas? BTW, I'm using HAProxy- on Gentoo Linux.

The header hash is in the todo list, with many other things, but is just not implemented right now. There are multiple things to consider for this, among which check/ignore case, specify which occurrence of the header to match, etc... so it will not be implemented tomorrow morning...

Right now, I do not see any easy method to ensure that all clients for a given host will get to the same server.

May I ask for what specific purpose you need the feature (I'm not trying to escape it's implementation, just trying to find a temporary workaround) ? Is it more for performance, for persistence, etc...

Willy Received on 2008/04/16 19:38

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