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.
---
doc/configuration.txt | 4 ++++
src/checks.c | 3 +++
2 files changed, 7 insertions(+)
diff --git a/doc/configuration.txt b/doc/configuration.txt
index 2295744..7c1edd8 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -2905,6 +2905,10 @@ http-check expect [!] <match> <pattern>
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.
diff --git a/src/checks.c b/src/checks.c
index feca96e..1b5b731 100644
--- a/src/checks.c
+++ b/src/checks.c
@@ -1427,6 +1427,9 @@ static int connect_conn_chk(struct task *t)
else if ((check->type) == PR_O2_HTTP_CHK) {
if (s->proxy->options2 & PR_O2_CHK_SNDST)
bo_putblk(check->bo, trash.str,
httpchk_build_status_header(s, trash.str, trash.size));
+ /* prevent HTTP keep-alive when "http-check expect" is
used */
+ if (s->proxy->options2 & PR_O2_EXP_TYPE)
+ bo_putstr(check->bo, "Connection: close\r\n");
bo_putstr(check->bo, "\r\n");
*check->bo->p = '\0'; /* to make gdb output easier to
read */
}
--
2.1.4
