To be fair, they had to upgrade to a development release (1.5) of HAProxy to configure it in this way. When we introduced the broxy at Braintree that feature did not exist.
(Disclosure - I work at Braintree)
(Disclosure - I work at Braintree)
(Disclosure - I also work at Braintree)
(We're planning on doing something similar in the future.)
"How we handle something <TECHNICAL> at balanced"
or
"How we handled <SITUATION> using <TECHNOLOGY> at balanced"
is of interest to this community.
No need to ask, get writing, hop to it! :)