Archive for the 'daemontools' Category

exec

Published
by
bisente
on Junio 9, 2008
in Command Line, English, Linuxadas, MacOS X and daemontools
. 2 Comments
  • english
  • spanish

exec is a built-in shell command that forces a binary to be executed by the currently running shell process instead of forking the process and running the binary on that child process.

When you run a command on a shell-script, it forks a child process and runs the command there. On a syscall level this is the classic:

if( (pid=fork()) == 0) {
    exec(command);
    exit();
}
wait();

And this is usually what we want, because we will keep running commands after that one. Nevertheless, sometimes this is a problem, like when:

  • we have a program that’s going to monitor a given process, and it doesn’t run properly if there’s an intermediate shell process but we need to run this second process via a shel-script for whatever reasons (to initialize some variables, run the program with nice, whatever)
  • on MacOS we’re running a program via a shell-script and get two icons on the dock, one for the shell and another one for the program

Running a command with exec forces the shell not to fork, but to run the command directly over the shell process. An important thing to note here is that the shell-script will end there, no further commands of the shell script will be executed as the shell process will be substituted by the command process, so to speak.

#!/bin/sh

# initialize variables, parse command-line parameters, etc.
export IP=$1

exec nice command $*
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My new server

Published
by
bisente
on Abril 26, 2008
in English, Frikadas, Linuxadas, MacOS X, Tecnología and daemontools
. 0 Comments
  • english
  • spanish

Ladies and gentleman, let me please introduce you to my new server, the one I’ve been blogging about lately:

dscf0042.JPG dscf0044.JPG

What? You don’t see it? Yes! The small grey box on top of the iomega disk, slightly bigger than the Fonera…

In case you don’t know it yet, it’s a Linksys NSLU2, a small device around $100 that comes with two USB2 ports and an ethernet connection. Plug an external USB hard drive to it and it’ll become available over the network like a NAS share. And the best part is: you can flash its firmware and install Debian!! :-D

It’s not that powerful, it has an XScale (ARM) processor at 266Mhz and only 32Mb of RAM. There are pages explaining how to install up to 256Mb. Nevertheless, it works and is small, doesn’t make noise, and has a small electrical consumption.

Up to now I’m running the following on it and it works quite well:

top-nslu2.png

# cat /proc/cpuinfo
Processor	: XScale-IXP42x Family rev 2 (v5l)
BogoMIPS	: 266.24
Features	: swp half fastmult edsp
CPU implementer	: 0x69
CPU architecture: 5TE
CPU variant	: 0x0
CPU part	: 0x41f
CPU revision	: 2
Cache type	: undefined 5
Cache clean	: undefined 5
Cache lockdown	: undefined 5
Cache format	: Harvard
I size		: 32768
I assoc		: 32
I line length	: 32
I sets		: 32
D size		: 32768
D assoc		: 32
D line length	: 32
D sets		: 32

Hardware	: Linksys NSLU2
Revision	: 0000
Serial		: 0000000000000000

# free
             total       used       free     shared    buffers     cached
Mem:         29988      28988       1000          0        404       4808
-/+ buffers/cache:      23776       6212
Swap:       979924      41164     938760

# uname -a
Linux eliza 2.6.18-6-ixp4xx #1 Tue Feb 12 00:57:53 UTC 2008 armv5tel GNU/Linux

# pstree
init-+-afpd---afpd
     |-atalkd
     |-atd
     |-avahi-daemon---avahi-daemon
     |-cnid_metad
     |-cron
     |-dbus-daemon
     |-events/0
     |-getty
     |-khelper
     |-klogd
     |-ksoftirqd/0
     |-kthread-+-aio/0
     |         |-kblockd/0
     |         |-khubd
     |         |-3*[kjournald]
     |         |-kmirrord
     |         |-kpsmoused
     |         |-kseriod
     |         |-kswapd0
     |         |-2*[pdflush]
     |         |-scsi_eh_0
     |         `-usb-storage
     |-mtdblockd
     |-nmbd
     |-papd
     |-portmap
     |-rpc.statd
     |-slpd
     |-smbd---smbd
     |-sshd---sshd---sshd---bash---su---bash---pstree
     |-svscanboot-+-readproctitle
     |            `-svscan-+-supervise---dnscache
     |                     |-3*[supervise---multilog]
     |                     |-supervise---tinydns
     |                     `-supervise---mlnet---mlnet---mlnet
     |-syslogd
     `-udevd
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Daemontools scripts for lighttpd and PHP

Published
by
bisente
on Septiembre 24, 2007
in English, daemontools and lighttpd
. 0 Comments
  • english
  • spanish

I’ve prepared a set of daemontools scripts to launch and monitor lighttpd and its PHP processes spawned with spawn-fcgi. Here is the README, a tar file with the scripts, and here you can browse the directories with all the scripts.

PS: yes, I like daemontools. It helps me achieving high availability with many services, keeping them up even when a server misbehaves and some process dies. This avoids a lot of late night calls. It’s a great invention. :)

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Asterisk clusters with a foneBRIDGE2

Published
by
bisente
on Agosto 26, 2007
in Asterisk, English, Linuxadas, Tecnología and daemontools
. 6 Comments
  • english
  • spanish

At work we have an Asterisk cluster comprised of two Proliant servers and a Redfone’s foneBRIDGE2 that handles the ISDN lines. The heartbeat daemon is installed on both servers, monitors them and, in the event of a system failure on the master, switches the service to the backup server, migrating the main IP and activating all the needed daemons. I’ll briefly explain the whole setup here as a reference.

Overview

As I’ve said we have two Asterisk servers, named asterisk00 and asterisk01.example.com, the former being the master. Each one of them has its IP address (say, 10.10.10.1 and .2) and there’s an additional “virtual” address (.3) that will “jump” from one server to the other if the primary crashes.

Our foneBRIDGE2 is a quad model, but we only use two ISDN lines: one to our telco, and the other to a legacy PBX. Besides the ISDN interfaces, the foneBRIDGE has two ethernet sockets to connect it to the servers, but only one of them (the first one) accepts configuration commands to set up the FB, switch servers, etc. You’d usually use a switch on that interface so that every server has access to it and can configure the FB, but my boss saw this switch as a single point of failure and refused to use one, a opinion I don’t share as it also has its drawbacks as we’ll see. So our setup is a little bit funny in that asterisk01 is connected to the primary FB interface and asterisk00 to the secondary one. The logic here is: asterisk00 is going to be running 99% of the time, and if it crashes, asterisk01 would have to re-configure the FB, so asterisk01 needs to have access to the config port. Of course, now asterisk01 is a SPOF: if our backup server goes down for any reason, we risk losing control of the FB rendering our cluster unusable!

We use the FreePBX web GUI, which in turn uses a mySQL DB to store all the settings. If you don’t use it, you can skip all instructions referring to mySQL and Apache.

mySQL synchronization

mySQL’s native ndb clustering is quite useful here. Set it up, have the service up at all times on both nodes, and the DB system automatically handles the synchronization across the cluster.

Setting up a mySQL cluster is out of the scope of this document, check the official docs here or look for a howto on Google. :)

Filesystem synchronization

All of Asterisk’s config files, libraries, modules, the users’ voicemail dirs… need to be synchronized over the cluster’s nodes. There are several alternatives here:

  • A SAN. Expensive but convenient. We don’t have one so it’s out of the question. :)
  • DRBD. If you don’t know it, think of it as a partition-level RAID1 system over the network. Works great, we use it on several other clusters, but not here. DRBD’s only drawback is that the synchronized partition can’t be mounted on both servers at once, so you can access the files only on the active node. We wanted to have everything accessible on both servers so that we could use the backup one as a testing ground for new configurations, software upgrades, etc., do DRBD wasn’t and option.
  • csync2. It’s like rsync on steroids. Similar to unison, but can synchronize files over more than two nodes. We’re using it for our Asterisk cluster.

Our csync2.conf file looks like this:

  1. group asterisk
  2. {
  3. host asterisk00.example.com asterisk01.example.com;
  4.  
  5. key /etc/csync2.key_asterisk;
  6.  
  7. backup-directory /var/backups/csync2;
  8. backup-generations 10;
  9.  
  10. auto none;
  11.  
  12. exclude  *~ .* ok lock control;
  13. include /etc/csync2.cfg;
  14.  
  15. include /etc/hosts;
  16. include /etc/ha.d/ha.cf;
  17. include /etc/ha.d/haresources;
  18.  
  19. include /etc/asterisk;
  20. include /etc/redfone*;
  21.  
  22. include /var/www;
  23. include /var/lib/asterisk;
  24. include /var/spool/asterisk;
  25. include /usr/lib/asterisk;
  26. include /etc/amportal.conf;
  27. include /var/log/asterisk;
  28. }

We run the synchronization every five minutes. There’s no need to sync more frequently, as there won’t be that many changes in the configuration (it’s a stable system, maybe a new phone added every X weeks) and we seldom use the voicemail. The synchronization is launched from /etc/cron.d/FB-csync2:

  1. */5 * * * * root [ -f /tmp/.FB-master ] && /usr/sbin/csync2 -xv

This /tmp/.FB-master file is just a “flag” that marks the master server, so that the synchronization is only run there. On the section about heartbeat we’ll see how and when this file is created.

fonulator

fonulator is Redfone’s utility to configure the foneBRIDGE. As I’ve explained before, only asterisk01 (the backup system) can configure the FB in our setup, and each server is connected to a different ethernet port on the FB. So in the event of a crash, we need to change the destination server AND the interface used to send it the TDMoE frames.

To this end, we have two different redfone.conf files (redfone_asterisk00.conf and redfone_asterisk01.conf). They look the same except for the “serverX” and “fbX” directives on the spans:

  1. [globals]
  2. fb1=00:50:C2:65:D0:68
  3. fb2=00:50:C2:65:D0:69
  4.  
  5. # asterisk00.example.com
  6. server1=00:80:5A:61:E7:FF
  7. # asterisk01.example.com
  8. server2=00:04:76:11:A3:EC
  9.  
  10. card=eth1,fb1
  11.  
  12. # Telco
  13. [span1]
  14. span=1,0,0,ccs,hdb3,crc4
  15. server1
  16. fb2
  17. pri
  18.  
  19. # Legacy PBX
  20. [span2]
  21. span=2,0,0,ccs,hdb3,crc4
  22. server1
  23. fb2
  24. pri

That was redfone_asterisk00.conf. It instructs the FB to send the ISDN traffic to asterisk00 (server1 here) over the second ethernet interface (fb2). The redfone_asterisk01.conf file uses server2 and fb1.

heartbeat

And now, the final piece that ties the rest together: heartbeat. Our haresources file looks like this:

  1. asterisk00.example.com MailTo::asterisk@example.com::Asterisk 10.10.10.3 FB_fonulator FB_master FB_asterisk apache2

Meaning that:

  • asterisk00.example.com is the master server
  • in the event of a service takeover, send a mail to asterisk@example.com
  • the service’s virtual IP is 10.10.10.3
  • start (stop) the FB_fonulator, FB_master, FB_asterisk and apache2 services (remember to unlink the apache2 link from /etc/rc2.d, we don’t want it to be started at system bootup as heartbeat will handle it)

Now, the scripts. FB_fonulator runs fonulator in order to configure the FB and send the TDMoE traffic to the appropriate server. One important thing here is that, although this script will be run on both servers, it will only have an effect when run from asterisk01 as this is the server on the FB’s config interface:

  1. #!/bin/sh
  2.  
  3. # Chech who I am and who the other host is
  4. THISHOST=“`hostname|cut -d. -f1`”
  5. if [ “$THISHOST” == “asterisk00″ ]
  6. then
  7. OTHERHOST=“asterisk01″
  8. else
  9. OTHERHOST=“asterisk00″
  10. fi
  11.  
  12. # Bail out if there is no config file
  13. F=“/etc/redfone_$THISHOST.conf”
  14. [ ! -f “$F” ] && exit 0
  15. # Guess the appropiate interface card
  16. export ETH=`grep -E “^card=” “$F” | cut -d= -f2 | cut -d, -f1`
  17.  
  18. case “$1″ in
  19. start)
  20. echo “Fonulating…”
  21. /usr/local/bin/fonulator -s -t 1 “/etc/redfone_$THISHOST.conf”
  22. ;;
  23. stop)
  24. /usr/local/bin/fonulator -s -t 1 “/etc/redfone_$OTHERHOST.conf”
  25. ;;
  26. restart|status)
  27. echo “Fonulator $1″
  28. exit 0
  29. ;;
  30. esac
  31. exit 0

FB_master creates the /tmp/.FB-master “flag” file we talked about before, and forces a sync both on the start (to make sure both servers have the same data) and on the stop (to sync back to the primary server any changes after a takeover-and-back):

  1. #!/bin/sh
  2.  
  3. F=/tmp/.FB-master
  4.  
  5. case “$1″ in
  6. start)
  7. touch “$F”
  8. # Activate log rotation
  9. ln -sf /etc/asterisk/asterisk.logrotate /etc/logrotate.d/asterisk
  10. # Force sync of these dirs
  11. csync2 -fr /var/
  12. csync2 -fr /etc/asterisk/
  13. csync2 -xv
  14. ;;
  15. stop)
  16. if [ -f “$F” ]
  17. then
  18. # De-activate log rotation
  19. rm -f /etc/logrotate.d/asterisk
  20. # Force a last minute sync to the new master
  21. csync2 -fr /var/
  22. csync2 -fr /etc/asterisk/
  23. csync2 -xv
  24. rm -f “$F”
  25. fi
  26. ;;
  27. esac
  28. exit 0

Finally, FB_asterisk starts the Asterisk service. We run Asterisk via daemontools using my scripts available here, so basically what this FB_asterisk script has to do is “svc -u/-d /service/asterisk”:

  1. #!/bin/sh
  2.  
  3. case “$1″ in
  4. start)
  5. echo “Starting Asterisk…”
  6. # Check if Asterisk is already running
  7. if /usr/sbin/asterisk -r -x “quit”
  8. then
  9. echo “Already running”
  10. exit 0
  11. fi
  12. # Just in case…
  13. rm -f /service/*
  14. # Link services and start them up
  15. ln -sf /etc/asterisk/services/asterisk/ /service/asterisk
  16. ln -sf /etc/asterisk/services/fopserver/ /service/fopserver
  17. svc -u /service/*
  18. ;;
  19. stop)
  20. echo “Stopping Asterisk …”
  21. svc -d /service/*
  22. rm -f /service/*
  23. ;;
  24. restart)
  25. echo “Restarting Astarisk …”
  26. svc -t /service/*
  27. ;;
  28. reload)
  29. echo “Reloading Asterisk …”
  30. /usr/sbin/asterisk -r -x “reload”
  31. ;;
  32. status)
  33. echo “Checking Asterisk’s status …”
  34. /usr/sbin/asterisk -r -x “quit” && exit 0 || exit 1
  35. ;;
  36. esac
  37. exit 0

Download

All the aforementioned scripts and config files are available here. Think of them as a base to make your own Asterisk/foneBRIDGE setup. And feel free to mail me back any improvements, errors you may find, etc.

Si te ha interesado, ¿me invitas a una cerveza? / If you liked the post, would you buy me a beer?

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OpenVPN + daemontools

Published
by
bisente
on Mayo 9, 2007
in OpenVPN, Seguridad and daemontools
. 0 Comments
  • english
  • spanish

I run several VPNs with OpenVPN and more than once the VPN server has died on me, so I’ve made a set of scripts to monitor it with daemontools. They are here (README).

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Asterisk and daemontools

Published
by
bisente
on Abril 27, 2007
in Asterisk, English and daemontools
. 2 Comments
  • english
  • spanish

I’ve just released my daemontools “run” scripts for Asterisk. They are here: asterisk-daemontools [README]

The scripts let you configure via variables on the “env” dir the PATH to the Asterisk exec, the user and group to launch it with, and the startup options you want to pass it. About running Asterisk with a given user, I’ve found problems with Asterisk 1.2 and the -U and -G options, so the scripts only use those options if you’re running Asterisk 1.4 and revert to “su” otherwise.

There’s also a script forFlash Operator Panel’s “fopserver”.

I’m using these scripts on several Asterisk 1.2 and 1.4 servers with FreePBX.

Read the full article to see the “run” scripts.

Continue reading ‘ Asterisk and daemontools’

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Creative Commons Attribution-NonCommercial 2.5 Spain
Creative Commons Attribution-NonCommercial 2.5 Spain