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 <wdau...@gmail.com>
---
doc/configuration.txt | 21 +++++++++++++++++++++
include/haproxy/proxy-t.h | 2 +-
src/mux_h1.c | 3 ++-
src/proxy.c | 1 +
4 files changed, 25 insertions(+), 2 deletions(-)
diff --git a/doc/configuration.txt b/doc/configuration.txt
index cd8ab4b72..66571a566 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -3756,6 +3756,7 @@ option tcp-smart-connect (*) X -
X X
option tcpka X X X X
option tcplog X X X X
option transparent (*) X - X X
+option idle-close-on-response (*) X X X -
external-check command X - X X
external-check path X - X X
persist rdp-cookie X - X X
@@ -9836,6 +9837,26 @@ no option transparent
"transparent" option of the "bind" keyword.
+option idle-close-on-response
+no option idle-close-on-response
+ Avoid closing idle connections if a stop stop is in progress
+ May be used in sections : defaults | frontend | listen | backend
+ yes | yes | yes | no
+ Arguments : none
+
+ 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.
+
+
external-check command <command>
Executable to run when performing an external-check
May be used in sections : defaults | frontend | listen | backend
diff --git a/include/haproxy/proxy-t.h b/include/haproxy/proxy-t.h
index 8ca4e818d..421f900e2 100644
--- a/include/haproxy/proxy-t.h
+++ b/include/haproxy/proxy-t.h
@@ -82,7 +82,7 @@ enum PR_SRV_STATE_FILE {
#define PR_O_REUSE_ALWS 0x0000000C /* always reuse a shared connection */
#define PR_O_REUSE_MASK 0x0000000C /* mask to retrieve shared connection
preferences */
-/* unused: 0x10 */
+#define PR_O_IDLE_CLOSE_RESP 0x00000010 /* avoid closing idle connections
during a soft stop */
#define PR_O_PREF_LAST 0x00000020 /* prefer last server */
#define PR_O_DISPATCH 0x00000040 /* use dispatch mode */
#define PR_O_FORCED_ID 0x00000080 /* proxy's ID was forced in the
configuration */
diff --git a/src/mux_h1.c b/src/mux_h1.c
index 7b6ab946d..1ec6cb77c 100644
--- a/src/mux_h1.c
+++ b/src/mux_h1.c
@@ -2999,7 +2999,8 @@ static int h1_process(struct h1c * h1c)
*/
if (!(h1c->flags & H1C_F_IS_BACK)) {
if (unlikely(h1c->px->flags & (PR_FL_DISABLED|PR_FL_STOPPED))) {
- if (h1c->flags & H1C_F_WAIT_NEXT_REQ)
+ if (!(h1c->px->options & PR_O_IDLE_CLOSE_RESP) &&
+ h1c->flags & H1C_F_WAIT_NEXT_REQ)
goto release;
}
}
diff --git a/src/proxy.c b/src/proxy.c
index ff5e35e2c..245b6f8a5 100644
--- a/src/proxy.c
+++ b/src/proxy.c
@@ -80,6 +80,7 @@ const struct cfg_opt cfg_opts[] =
#else
{ "transparent", 0, 0, 0, 0 },
#endif
+ { "idle-close-on-response", PR_O_IDLE_CLOSE_RESP, PR_CAP_FE, 0,
PR_MODE_HTTP },
{ NULL, 0, 0, 0, 0 }
};
--
2.34.1
