05 July 2018

Running services using daemontools

Daemontools is the best way to manage your processes that is required to be running always. If you have processes like catalyst development server or spooler process that are required to be running always and needs to be self sustainable if they are killed for some reason.

Why Daemontools

http://cr.yp.to/daemontools/faq/create.html#why

	inittab	ttys	init.d	rc.local	/service
Easy service installation and removal	No	No	Yes	No	Yes
Easy first-time service startup	No	No	No	No	Yes
Reliable restarts	Yes	Yes	No	No	Yes
Easy, reliable signalling	No	No	No	No	Yes
Clean process state	Yes	Yes	No	No	Yes
Portability	No	No	No	No	Yes

Installing daemontools

Installing daemontools on Ubuntu - Version 1

apt-get install daemontools dameontools-run

This will install and setup autostart of svscanboot on system boot via /etc/inittab

SV:123456:respawn:/usr/bin/svscanboot

Installing daemontools on Ubuntu - Version 2

Install daemontools

apt-get -y install daemontools

Create /etc/service directory

mkdir -p /etc/service

need to make a conf file for booting

cd /etc/init/
touch svscan.conf

echo "start on runlevel [2345]" > svscan.conf
echo "" >> svscan.conf
echo "expect fork" >> svscan.conf
echo "respawn" >> svscan.conf
echo "exec svscanboot" >> svscan.conf

Start svscan service

service svscan start

That’s it. Now you can check it using command below:

ps -ef|grep svscan

Installting daemontools on Centos

Install wget gcc and wget

    yum install gcc wget

Create a folder setup and wget the source

   mkdir -p /package
   chmod 1755 /package
   cd /package
   wget http://cr.yp.to/daemontools/daemontools-0.76.tar.gz
   tar -xzvf daemontools-0.76.tar.gz
   rm daemontools-0.76.tar.gz

Install the daemontools

   echo gcc -O2 -include /usr/include/errno.h > src/conf-cc
   ./package/install

Fix Deamontools for CentOS 6.x. To do that simply remove the added line from /etc/inittab then issue this:

    echo "start on runlevel [12345]" > /etc/init/svscan.conf
    echo "respawn" >> /etc/init/svscan.conf
    echo "exec /command/svscanboot" >> /etc/init/svscan.conf

Start svscan service

    initctl reload-configuration
    initctl start svscan

That’s it. Now you can check it using command below:

    ps -ef|grep svscan

Creating service

Create /services directory where we store all our services

mkdir /services

mkdir /services/catalystd

Run file for catalystd

Create a file run inside /services/catalystd directory

#!/bin/sh


echo `date`."\n"
echo "\catalystd: Starting\n"

exec 2>&1

echo "catalystd: Setting ENV Variables\n"
export CATALYSTAPP_WWW_ROOR="/home/sheeju/projects/CatalystApp"
export PERL5LIB=/home/sheeju/projects/lib/:${PERL5LIB}
export PGSERVICEFILE=/home/sheeju/projects/pg_service.conf

exec /usr/bin/perl \
        /home/sheeju/projects/CatalystApp/script/catalystapp_server.pl

Run file for catalystd log

#!/bin/bash

PATH=/bin:/usr/bin:/usr/local/bin:/sbin:/usr/sbin:/usr/local/sbin:/bin
#exec cat > /var/log/parserspoold/test.log
multilog t n100 s16777215 /var/log/catalystd 2>&1

Daemontools Commands

Start service

ln -s /services/catalystd /etc/service

Remove service

rm /etc/service/catalystd
svc -dx /services/somerandomservice

Restart service

svc -t /service/somerandomservice
svc -k /service/somerandomservice

Check service uptime

sudo svstat /etc/service/catalystd
/etc/service/catalystd: up (pid 772) 349 seconds

Checking the logs

tail -f /var/log/catalystd/current

Checking the running processes

ps auxf
pstree -a 15234

Links

https://cr.yp.to/daemontools.html

https://isotope11.com/blog/manage-your-services-with-daemontools

Hi, I'm Sheeju Alex.

Sheeju Alex