Perlbal book -- table of contents

dormando dormando at
Sun Sep 24 00:12:56 UTC 2006

Brad Fitzpatrick wrote:
> A certain book company might want to do a book on Perlbal and was asking
> for a table of contents.
> I wrote this up:
> Any other suggestions?
> What do you guys want to see explained / documented / walked-through
> better?
> - Brad

Perhaps a tip or two about managing multiple perlbal instances running 
against the same pool of backend servers? I've hit gotchas with this 
while abusing connect-ahead (we never had backend keepalives working 
before, remember;) Minor, minor...

Hmm... One actual feature issue with perlbal that would make the book 
harder to work through is the lack of a "show running-config" type 
command. You can do a "show service blah", but that doesn't even display 
the entire config for the service. It's easy to tune perlbal at runtime, 
then completely forget what's been changed. (I see there's an open RT 
bug for this already).

Explain enable-error-retries?

Some confusing points of perlbal config vs commercial LBs: (that at 
least should be clarified/noted, if not actually fixed).

- You can create services and pools, enable/disable them, but not delete 
them. Most commercial LBs allow anything to be added/deleted without 

- It doesn't seem to be possible to write a plugin to do mod_rewrite 
style url rewriting? The only variable I could access for this was 
marked read-only. Again, I could be stupid, but it also proves that it's 
obnoxious to do. Market L7 LB's can do this.

- Load balancing your load balancer with linux LVS, iptables, OBSD PF, 
whatever? The answer to "perlbal is out of CPU!?" is to add more 
perlbals. This isn't usually done by LB users :P

- Maybe document some other features that are standard and often used 
by, say, a Big/IP, and don't exist within perlbal?

- Your streaming plugins were a really fancy whizz-bang web 2.0 "thing" 
that is very hard to do without something like perlbal. Explain/link at 
least one of those?

Wish I had more office hour time to hack on PB :)


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