BUG/MINOR: checks: prevent http keep-alive with http-check expect
Sébastien Rohaut reported that string negation in http-check expect didn't
work as expected.
The misbehaviour is caused by responses with HTTP keep-alive. When the
condition is not met, haproxy awaits more data until the buffer is full or the
connection is closed, resulting in a check timeout when "timeout check" is
lower than the keep-alive timeout on the server side.
In order to avoid the issue, when a "http-check expect" is used, haproxy will
ask the server to disable keep-alive by automatically appending a
"Connection: close" header to the request.
(cherry picked from commit 32602d23610981b48143d1f82885b8cfae286e0f)
diff --git a/doc/configuration.txt b/doc/configuration.txt
index 55c3e2f..e951959 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -2856,6 +2856,10 @@
waste some CPU cycles, especially when regular expressions are used, and that
it is always better to focus the checks on smaller resources.
+ Also "http-check expect" doesn't support HTTP keep-alive. Keep in mind that it
+ will automatically append a "Connection: close" header, meaning that this
+ header should not be present in the request provided by "option httpchk".
+
Last, if "http-check expect" is combined with "http-check disable-on-404",
then this last one has precedence when the server responds with 404.