Virtual hosts, existing apache and some more

Harmen harmen at
Mon Mar 14 16:12:38 PST 2005

On Mon, Mar 14, 2005 at 03:12:09PM -0800, Mark Smith wrote:
> Howdy!
> > I use a few virtualhosts now. Depending on (part of the) hostname requests
> > go to different backend mod_perl apaches. I would like to use Perlbal to
> > balance the connections to the backend servers, but since I really need the
> > frontends virtualhosts the setup would be: 
> > frontend apache -> perlbal -> mod_perl
> > But thats looks rather silly. Any suggestions? (Besides using real ipnumbers in
> > stead of virtualhosts)
> LiveJournal uses a BIG-IP hardware load balancer in front of the Perlbals
> in order to split requests by hostname.  We then define different ports on
> Perlbal to go to diferrent sets of backend nodes.

Aha. That explains. But a frontend apache is nice to have. It is fast
enough and does some other useful things. Any suggestions what to use to
connect to the Perlbal @ localhost? Plain old mod_rewrite/mod_proxy?

Ow, what does perlbal do with uploads? Does it wait for the whole upload
before it even tries to connect to the mod_perl server?

> There's no way right now to say "this hostname goes to this service", but
> that's not a terribly difficult thing to do.  Hmm, it could probably be
> added fairly easily.
> > In the oscon2004 presentation (which is quite readable even without the talk :)
> > there is a example of a GET request for a FotoBilder image. (, page 50 on my pdfreader)
> > The requests goes like this:
> > perlbal -> mod_perl -> mogile tracker -> redirects to a storage node via
> > perlbal -> serving of the actual image by perlbal.
> > This does look like quite a lot of work for a simple image :)
> > Do 'last-modified' headers get added to the reply somewhere so a client will
> > cache it, or does the livejournal setup do that somewhere?
> Lot of work, but we do set last-modified dates -- when the MogileFS storage
> node (really a Perlbal in web_server mode with put/delete turned on)
> returns the file, it adds a Last-Modified header.  LiveJournal/FotoBilder
> just pass it on to the user.

Does the FotoBuilder mod_perl handler check the If-modified-since headers?
(just curious)

> > (Hmm, I see wikipedia uses it between squid and mod_perl...)
> Yep, last I heard they're using it to balance among the mod_perls.
> > [...] mogile [...]
> And for your MogileFS questions, you should email the MogileFS mailing
> list.  I'd be happy to answer any questions asked there. :)

Ok, I will. That list can use some traffic :)

Thank you for your help,


                               The Moon is Waxing Crescent (24% of Full)

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