tree 5c96482b34d9661bf3d56e8e168b1426723411df
parent 589756727366f83b3cde070d75905f1791a75b37
author Willy Tarreau <w@1wt.eu> 1398370239 +0200
committer Willy Tarreau <w@1wt.eu> 1398370239 +0200
encoding latin1

BUG/MEDIUM: stats: mismatch between behaviour and doc about front/back

In version 1.3.4, we got the ability to split configuration parts between
frontends and backends. The stats was attached to the backend and a control
was made to ensure that it was used only in a listen or backend section, but
not in a frontend.

The documentation clearly says that the statement may only be used in the
backend.

But since that same version above, the defaults stats configuration is
only filled in the frontend part of the proxy and not in the backend's.
So a backend will not get stats which are enabled in a defaults section,
despite what the doc says. However, a frontend configured after a defaults
section will get stats and will not emit the warning!

There were many technical limitations in 1.3.4 making it impossible to
have the stats working both in the frontend and backend, but now this has
become a total mess.

It's common however to see people create a frontend with a perfectly
working stats configuration which only emits a warning stating that it
might not work, adding to the confusion. Most people workaround the tricky
behaviour by declaring a "listen" section with no server, which was the
recommended solution in 1.3 where it was even suggested to add a dispatch
address to avoid a warning.

So the right solution seems to do the following :

  - ensure that the defaults section's settings apply to the backends,
    as documented ;

  - let the frontends work in order not to break existing setups relying
    on the defaults section ;

  - officially allow stats to be declared in frontends and remove the
    warninng

This patch should probably not be backported since it's not certain that
1.4 is fully compatible with having stats in frontends and backends (which
was really made possible thanks to applets).