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[DOC] document "nbsrv" and "monitor fail"

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Willy Tarreau 2007-12-02 17:31:20 +01:00
parent 240f9fd1bc
commit c7246fcdf3
1 changed files with 34 additions and 2 deletions
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36
doc/configuration.txt
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@ -261,6 +261,7 @@ http-check disable-on-404 X - X X
log X X X X
maxconn X X X -
mode X X X X
monitor fail - X X -
monitor-net X X X -
monitor-uri X X X -
option abortonclose X - X X
@ -605,6 +606,13 @@ hdr_cnt(header) <integer>
contain more than one of certain headers. See "hdr" for more information on
header matching.
nbsrv <integer>
nbsrv(backend) <integer>
Returns true when the number of usable servers of either the current backend
or the named backend matches the values or ranges specified. This is used to
switch to an alternate backend when the number of servers is too low to
to handle some load. It is useful to report a failure when combined with
"monitor fail".
2.1.6) Pre-defined ACLs
-----------------------
@ -676,7 +684,31 @@ and to every request on the "img", "video", "download" and "ftp" hosts :
See below for the detailed help on the "block" and "use_backend" keywords.
2.2) Options
2.2) Instance-specific keywords and statements
----------------------------------------------
monitor fail [if | unless] <condition>
[ supported in: frontend, listen ]
This statement adds a condition which can force the response to a monitor
request to report a failure. By default, when an external component queries
the URI dedicated to monitoring, a 200 response is returned. When one of the
conditions above is met, haproxy will return 503 instead of 200. This is
very useful to report a site failure to an external component which may base
routing advertisements between multiple sites on the availability reported by
haproxy. In this case, one would rely on an ACL involving the "nbsrv"
criterion.
Example:
frontend www
acl site_dead nbsrv(dynamic) lt 2
acl site_dead nbsrv(static) lt 2
monitor-uri /site_alive
monitor fail if site_dead
2.3) Options
------------
A handful of options affect the way the load balancing is performed or reaction
@ -703,7 +735,7 @@ option contstats
it is not enabled by default, as it has small performance impact (~0.5%).
2.3) Server options
2.4) Server options
-------------------
slowstart <start_time_in_ms>