tree 45267bf53a8c6f247981f1083c33f87bc5a401c4
parent 7c565501e91f3759274dd7cd43ec9de7c4b9a162
author William Dauchy <wdauchy@gmail.com> 1641419604 +0100
committer Willy Tarreau <w@1wt.eu> 1641456982 +0100
encoding latin1

MINOR: proxy: add option idle-close-on-response

Avoid closing idle connections if a soft stop is in progress.

By default, idle connections will be closed during a soft stop. In some
environments, a client talking to the proxy may have prepared some idle
connections in order to send requests later. If there is no proper retry
on write errors, this can result in errors while haproxy is reloading.
Even though a proper implementation should retry on connection/write
errors, this option was introduced to support back compat with haproxy <
v2.4. Indeed before v2.4, we were waiting for a last request to be able
to add a "connection: close" header and advice the client to close the
connection.

In a real life example, this behavior was seen in AWS using the ALB in
front of a haproxy. The end result was ALB sending 502 during haproxy
reloads.
This patch was tested on haproxy v2.4, with a regular reload on the
process, and a constant trend of requests coming in. Before the patch,
we see regular 502 returned to the client; when activating the option,
the 502 disappear.

This patch should help fixing github issue #1506.
In order to unblock some v2.3 to v2.4 migraton, this patch should be
backported up to v2.4 branch.

Signed-off-by: William Dauchy <wdauchy@gmail.com>
[wt: minor edits to the doc to mention other options to care about]
Signed-off-by: Willy Tarreau <w@1wt.eu>
(cherry picked from commit a9dd901143385fef3a5113d0bf1681cd0536357a)
Signed-off-by: Willy Tarreau <w@1wt.eu>
(cherry picked from commit 3c8633740601062e314722982ae2049f24828942)
[wt: adjusted context; no PR_FL_DISABLED in 2.4, use px->disabled]
Signed-off-by: Willy Tarreau <w@1wt.eu>