From 2df8cad0fea2d1a4ca8dd58f384df3c3c3f5d7ee Mon Sep 17 00:00:00 2001 From: Willy Tarreau Date: Mon, 1 Jul 2019 07:51:29 +0200 Subject: [PATCH] BUG/MEDIUM: checks: unblock signals in external checks As discussed in issue #140, processes are forked with signals blocked resulting in haproxy's kill being ignored. This happens when the command takes more time to complete than the configured check timeout or interval. Just calling "sleep 30" every second makes the problem obvious. The fix simply consists in unblocking the signals in the child after the fork. It needs to be backported to all stable branches containing external checks and where signals are blocked on startup. It's unclear when it started, but the following config exhibits the issue : global external-check listen www bind :8001 timeout client 5s timeout server 5s timeout connect 5s option external-check external-check command "$PWD/sleep10.sh" server local 127.0.0.1:80 check inter 200 $ cat sleep10.sh #!/bin/sh exec /bin/sleep 10 The "sleep" processes keep accumulating for 10 seconds and stabilize around 25 when the bug is present. Just issuing "killall sleep" has no effect on them, and stopping haproxy leaves these processes behind. --- src/checks.c | 1 + 1 file changed, 1 insertion(+) diff --git a/src/checks.c b/src/checks.c index c175a752d..e31eb1735 100644 --- a/src/checks.c +++ b/src/checks.c @@ -1997,6 +1997,7 @@ static int connect_proc_chk(struct task *t) environ = check->envp; extchk_setenv(check, EXTCHK_HAPROXY_SERVER_CURCONN, ultoa_r(s->cur_sess, buf, sizeof(buf))); + haproxy_unblock_signals(); execvp(px->check_command, check->argv); ha_alert("Failed to exec process for external health check: %s. Aborting.\n", strerror(errno));