please reproduce: rc.httpd force-restart stops, but does not restart, httpd

metaed · 08-15-2023, 12:11 PM

The command
# /etc/rc.d/rc.httpd force-restart
does not work for me. It successfully stops all httpd processes, but does not restart them. The output is:

(98)Address already in use: AH00072: make_sock: could not bind to address [::]:80
(98)Address already in use: AH00072: make_sock: could not bind to address 0.0.0.0:80
no listening sockets available, shutting down
AH00015: Unable to open logs

I can reliably reproduce the behavior on two different Slackware-64 15.0 nodes by

running pgrep -a httpd (to verify httpd processes are running),
running rc.httpd force-restart, and
running pgrep -a httpd again (to verify the restart failed).

I suspect a timing issue, where httpd is not fully stopped yet when the restart begins. But before I start to work on it, can anyone else confirm this behavior with Slackware-64 15.0?

jayjwa · 08-15-2023, 12:38 PM

I've seen this for a long time now. I usually do 'rc.httpd stop' (wait awhile) 'rc.httpd start'. Slackware current. Maybe a 'sleep' command in there would help.

scuzzy_dog · 08-15-2023, 02:38 PM

If you just want to reload .conf files then do

apachectl graceful

That's usually worked for me.

https://httpd.apache.org/docs/2.4/stopping.html

metaed · 08-15-2023, 03:38 PM

Quote:

Originally Posted by jayjwa

I've seen this for a long time now. I usually do 'rc.httpd stop' (wait awhile) 'rc.httpd start'. Slackware current. Maybe a 'sleep' command in there would help.

Now that you’ve confirmed the behavior, that’s what I’m going to try first.

Quote:

Originally Posted by scuzzy_dog

If you just want to reload .conf files then do
apachectl graceful

You’re right, but the actual use-case is reloading patched executables after a security update. Today it was a patch release of mariadb, which replaced /usr/lib64/libmariadb.so.3, which is linked to by /usr/sbin/httpd. apachectl graceful does not reload executables from disk, so it’s not enough.

metaed · 08-15-2023, 04:22 PM

This patch to /etc/rc.d/rc.httpd solves it for me. Again this is for stock Slackware-64 15.0.

Code:

--- rc.httpd.orig       2021-12-20 18:31:27.000000000 +0000
+++ rc.httpd    2023-08-15 21:18:03.775517444 +0000
@@ -22,10 +22,15 @@
   ;;
   'force-restart')
     # Because sometimes restarting through apachectl just doesn't do the trick...
+    echo stopping httpd nicely
     /usr/sbin/apachectl -k stop
-    pkill -f /usr/sbin/httpd
+    ( sleep 1 ; echo stopping httpd less nicely ; pkill -f /usr/sbin/httpd ) &
+    sleeper=$!
+    pwait -f /usr/sbin/httpd
+    kill -0 $sleeper && kill $sleeper || true
     # Remove both old and new .pid locations:
     rm -f /var/run/httpd.pid /var/run/httpd/httpd.pid
+    echo starting httpd
     /usr/sbin/apachectl -k start
   ;;
   'restart')

volkerdi · 08-15-2023, 05:39 PM

I suspect that pwait is the missing bit, and that pkill really shouldn't be used unless the .pid files are missing (they shouldn't be, but I'll avoid removing that fallback anyway).

So, how about this?

Code:

#!/bin/sh
#
# /etc/rc.d/rc.httpd
#
# Start/stop/force-restart/restart/graceful[ly restart]/graceful[ly]-stop
# the Apache (httpd) web server.
#
# To make Apache start automatically at boot, make this
# file executable:  chmod 755 /etc/rc.d/rc.httpd
#
# For information on these options, "man apachectl".

case "$1" in
  'start')
    /usr/sbin/apachectl -k start
  ;;
  'stop')
    if [ ! -r /var/run/httpd.pid -a ! -r /var/run/httpd/httpd.pid ]; then
      pkill -f /usr/sbin/httpd
    else
      /usr/sbin/apachectl -k stop
    fi
    pwait -f /usr/sbin/httpd
  ;;
  'force-restart')
    if [ ! -r /var/run/httpd.pid -a ! -r /var/run/httpd/httpd.pid ]; then
      pkill -f /usr/sbin/httpd
    else
      /usr/sbin/apachectl -k stop
    fi
    pwait -f /usr/sbin/httpd
    /usr/sbin/apachectl -k start
  ;;
  'restart')
    /usr/sbin/apachectl -k restart
  ;;
  'graceful')
    /usr/sbin/apachectl -k graceful
  ;;
  'graceful-stop')
    /usr/sbin/apachectl -k graceful-stop
  ;;
  *)
    echo "Usage: $0 {start|stop|force-restart|restart|graceful|graceful-stop}"
  ;;
esac

metaed · 08-15-2023, 06:30 PM

Quote:

Originally Posted by volkerdi

I suspect that pwait is the missing bit

Yes, and your solution is fine. My first draft actually just changed one word, pkill to pwait, and that worked perfectly for me.

I noticed that the legacy force-restart code seems designed to stop httpd even under unusual circumstances, when apachectl -k stop is ineffective. I have heard of that happening, though not to me. That's why I put back the pkill, behind a one-second grace period. I agree under normal conditions it is, well, overkill.