Centos – Apache Server shutting down, whats the reason

apache-2.2centosPHP

I'm quite new to Linux so I don't really know how to fix this problem.

I have a vServer running on CentOS, managed by Plesk 10. My website shuts down randomly for a few hours now.

The error in the apache log says the following:

[Sun Aug 19 21:31:00 2012] [notice] caught SIGTERM, shutting down
[Sun Aug 19 21:32:21 2012] [notice] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)
[Sun Aug 19 21:32:22 2012] [warn] RSA server certificate CommonName (CN) `Parallels Panel' does NOT match server name!?
[Sun Aug 19 21:32:22 2012] [warn] RSA server certificate CommonName (CN) `Parallels Panel' does NOT match server name!?
[Sun Aug 19 21:32:22 2012] [warn] RSA server certificate CommonName (CN) `Parallels Panel' does NOT match server name!?
[Sun Aug 19 21:32:22 2012] [warn] Init: Name-based SSL virtual hosts only work for clients with TLS server name indication support (RFC 4366)
[Sun Aug 19 21:32:22 2012] [notice] Digest: generating secret for digest authentication ...
[Sun Aug 19 21:32:22 2012] [notice] Digest: done
PHP Warning:  Directive 'safe_mode' is deprecated in PHP 5.3 and greater in Unknown on line 0
[Sun Aug 19 21:32:22 2012] [warn] RSA server certificate CommonName (CN) `Parallels Panel' does NOT match server name!?
[Sun Aug 19 21:32:22 2012] [warn] RSA server certificate CommonName (CN) `Parallels Panel' does NOT match server name!?
[Sun Aug 19 21:32:22 2012] [warn] RSA server certificate CommonName (CN) `Parallels Panel' does NOT match server name!?
[Sun Aug 19 21:32:22 2012] [warn] Init: Name-based SSL virtual hosts only work for clients with TLS server name indication support (RFC 4366)
[Sun Aug 19 21:32:22 2012] [notice] Apache/2.2.15 (Unix) DAV/2 mod_fcgid/2.3.6 mod_ssl/2.2.15 OpenSSL/1.0.0-fips configured -- resuming normal operations

Best Answer

Something is sending it sigterm, says the first line. That will always originate externally. Perhaps there is a cronjob set to restart it periodically? Perhaps there is a problem with plesk? It is impossible to say from that log what has happened, except that something issued a command to shut it down.

It's possible, given that it is doing init stuff after it's stopped, that a watchdog is assuming it is hung and restarting it. If that's the case, and you notice it's down for a while, check that you have enough entropy in your entropy pool or change the random device to /dev/urandom (possible security weakness if you do that). After it is started, apache will often block and wait for random data (for SSL) before servicing any requests, SSL or not.

Related Solutions

Linux – Apache server keeps crashing regularly

I'm not saying this is what's happening but based on my own experience as a CentOS admin, it's most likely runaway apache/php processes taking down the server. I've seen this numerous times on CentOS 5. It's frustrating because there's usually not a trace of what happened in the log files. The machine just grinds to a halt due to physical memory and swap being sucked up by apache/php processes. You would think linux memory management or some daemon would jump in and say "hey stop" but it doesn't. It'll let apache grind your system to a halt.

Having said that, to see what's happening you'll need something that can monitor and log resource usage. I like to use a program called atop. Atop is a lot like the top program but it also takes a snapshot of resource usage at defined intervals. It's pretty simple to install.

wget http://www.atcomputing.nl/Tools/atop/packages/atop-1.23.tar.gz 
tar -zxvf atop-1.23.tar.gz
cd atop-1.23 && make install

Open /etc/atop/atop.daily with a text editor and change INTERVAL=600 to INTERVAL=60

Run the command /etc/atop/atop.daily from a command prompt to start it. Wait a few minutes and run atop -r /var/log/atop/atop_20091118 with the correct date of course.

Hit the t key to go forward in time and T to go back. Next time your server crashes do this and check the MEM free and SWP free lines. If you have memory problems these will be in red. Also look for numerous httpd lines under CMD. If apache/php is your problem there'll be a bunch of them.

If this is the case, I recommend looking at you're MaxClients setting in httpd.conf. If set too high, apache will gladly eat all of your memory causing your machine to crash. Apache/php can easily eat 40-50MB/process. If you multiply 40mb x MaxClients you'll get a rough idea of how much memory apache can potentially use. MaxClients usually defaults to 150 on CentOS so apache can potentially use 6GB of memory by default. This doesn't include memory your system needs for itself and other processes to run. Try setting it to a more realistic value based on the amount of memory you have like 40 if you have 2G of memory and see if that helps. Also if you have KeepAlive On, set KeepAliveTimeout to a low number like 2 or 3.

In my opinion CentOS's apache/php compilation is a real pos that should never have seen the light of day. It's buggy and crash prone. If you run a serious site, I highly recommend compiling your own version of apache/php or even using one of the newer high performance webservers like lighttpd or nginx with fgci php.

SSL, Apache, and Subdomains on a Static IP

"RSA server certificate CommonName (CN) `*.mysite.com' does NOT match server name!? " is a normal warning when using wildcard certificates and it can safely be ignored. That isn't the reason why SSL isn't working. If you don't see any other errors in your logs, make sure that everything is forwarding port 443 properly.

Best Answer

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Linux – Apache server keeps crashing regularly

SSL, Apache, and Subdomains on a Static IP

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