Introduction
For a production environment you probably don't want to have to manually start and stop your Pylons server every time the machine reboots. Which means you need a robust solution to ensure the application is always running and is automatically restarted if it exists for some reason.
This recipe focuses on writing these scripts by hand. For alternate solutions, check these recipes:
Creating Init Scripts
Create a file /etc/init.d/pylons which looks like this:
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16 | #!/bin/sh -e
case "$1" in
start)
paster serve --daemon --pid-file=/MyProject/paster.pid --log-file=/MyProject/paster.log /MyProject/development.ini start
;;
stop)
paster serve --daemon --pid-file=/MyProject/paster.pid --log-file=/MyProject/paster.log /MyProject/development.ini stop
;;
restart)
paster serve --daemon --pid-file=/MyProject/paster.pid --log-file=/MyProject/paster.log /MyProject/development.ini restart
;;
*)
echo $"Usage: $0 {start|stop|restart}"
exit 1
esac
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You should adjust the paths to point to the correct places for your .pid, .log and .ini files.
Make the file executable
chmod 755 /etc/init.d/pylons
Then for each of the directories /etc/rc2.d /etc/rc3.d /etc/rc4.d and /etc/rc5.d you should run the following commands:
cd /etc/rc2.d
ln -s ../init.d/pylons S20pylons
Different platforms have slightly different runlevels so you should run the above commands for whichever directories are appropriate on your platform.
You should now be able to start, stop and restart the server with the following commands and you should find the server loads when the system loads and stops when the system is shutdown:
/etc/init.d/pylons start
/etc/init.d/pylons stop
/etc/init.d/pylons restart
Each time you start the server the MyProject/paster.pid and MyProject/paster.log files will be created and each time you stop the server they will be deleted. The MyProject/paster.pid file contains the process ID of the server so if you restart the server, the number stored in the file will change.
If the server is not running you will not be able to restart it, you'll have to use the /etc/init.d/pylons start command first.
Setting Up A Cron Job
Although the paster server will now start and stop when the server loads and shuts down it would be nice to have a have a cron job that checks it is alive every few minutes and can restart it if necessary.
Issue this command to edit your crontab:
Then add the following entry:
*/1 * * * * paster serve --daemon --pid-file=/MyProject/paster.pid --log-file=/MyProject/paster.log /MyProject/development.ini
This will try to start the daemon every minute. There is an explanation of these settings at this site http://www.unixgeeks.org/security/newbie/unix/cron-1.html
and you are obviously free to change how often the server is restarted to suit your needs. There is no reason to expect the server would crash so every minute should be more than enough.
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When using cron jobs it is usually a good idea to specify a MAILTO address so that the output of the commands is emailed to you. This is useful if the command you run outouts an error message when it fails. Run crontab -e again and then add this at the very top, replacing it with your own email address:
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If you don't like the default editor chosen for you to edit your list of cron jobs you can change it by setting the EDITOR variable. If you are using the bash shell you do so like this:
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Posted by
This doesn't work for me because of the enviorment, i rather use this:
#!/bin/sh -e