Hudson is a great little Continuous Integration server. One of Kosuke's more recent innovations has been to add a feature that lets you install Hudson as a service on Windows. A very useful feature indeed, as previously this was a fairly non-trivial operation. But what if you're running Hudson on a Linux server?

Now there are a few ways to do this. One possibility for example is to install Tomcat as a service and then deploy Hudson onto this server. There is plenty of documentation on the internet about how to install Tomcat as a service on a linux machine. But what if you don't like Tomcat? What if your quite happy with Hudson's built in web server, and can't be bothered setting up Tomcat on your server? You can by all means set up Hudson as a service by itself, and it isn't hard to do. A few techniques are documented on the Hudson web site. I recently went through the process on a Redhat linux machine, which is a little different from the examples on the side. So, for the record, here is a short rundown on how I did it.

First of all, it's a good idea to have a dedicated hudson user. You can create one in the standard Unix fashion, as shown here:

#adduser -m -s /bin/bash hudson

Next, you need to download the hudson.war file and place in in an appropriate directory. I put mine in /usr/share/hudson.

#mkdir /usr/share/hudson
#cd /usr/share/hudson
#wget http://hudson.gotdns.com/latest/hudson.war
#chmod 755 /usr/share/hudson/hudson.war

You can create simple start and stop scripts for Hudson as shown below. The start script (which I place in /usr/local/bin/start-hudson.sh) looks like this:

#!/bin/bash
HUDSON_WAR=/usr/share/hudson/hudson.war
HUDSON_LOG=/home/hudson/hudson.log
JAVA=$JAVA_HOME/bin/java
nohup nice $JAVA -jar $HUDSON_WAR > $HUDSON_LOG 2>&1 &

The stop script (/usr/local/bin/stop-hudson.sh) is a fairly basic one, as shown here:

#!/bin/bash
kill `ps -ef | grep hudson.war | grep -v grep | awk '{ print $2 }'`

Next, to make your installation a little cleaner, you can write a simple init script to start and stop Hudson using these scripts. The following is a very basic example, which starts and stops Hudson, and runs Hudson as the 'hudson' user (running Hudson as root is not a good idea):

#! /bin/bash
#
# hudson	Start/Stop the Hudson Continuous Integration server.
#
# chkconfig: 345 91 10
# description: Hudson is a Continuous Integration server. \
#              It monitors a source code repository and triggers builds \
#              when it detects any changes. See https://hudson.dev.java.net/ \
#              for more details.
# processname: hudson
# pidfile: /var/run/hudson.pid


# Source function library.
. /etc/rc.d/init.d/functions

# Get config.
. /etc/sysconfig/network

# Check that networking is up.
[ "${NETWORKING}" = "no" ] && exit 0

startup=/usr/local/bin/start-hudson.sh
shutdown=/usr/local/bin/stop-hudson.sh
export JAVA_HOME=/usr/java/jdk1.6.0
HUDSON_USER=hudson

start(){
 echo -n $"Starting Hudson service: "
 su - $HUDSON_USER -c $startup
 RETVAL=$?
 echo
}

stop(){
 action $"Stopping Hudson service: " 
 su - $HUDSON_USER -c $shutdown 
 RETVAL=$?
 echo
}

status(){
 numproc=`ps -ef | grep hudson.war | grep -v "grep hudson.war" | wc -l`
 if [ $numproc -gt 0 ]; then
  echo "Hudson is running..."
  else
  echo "Hudson is stopped..."
 fi
}

restart(){
  stop
  start
}


# See how we were called.
case "$1" in
start)
 start
 ;;
stop)
 stop
 ;;
status)
 status
 ;; 
restart)
 restart
 ;;
*)
 echo $"Usage: $0 {start|stop|status|restart}"
 exit 1
esac

exit 0

Place this script in the /etc/init.d directory (e.g. /etc/init.d/hudson), and make it executable.

#chmod a+x /etc/init.d/hudson 

Now you can start and stop Hudson in a familiar Unix fashion:

# /etc/init.d/hudson start
Starting Hudson service:
# /etc/init.d/hudson status
Hudson is running...
# /etc/init.d/hudson stop
Stopping Hudson service:                                   [  OK  ]
# /etc/init.d/hudson status
Hudson is stopped...

Finally, you can set this up to start and stop when the server reboots, by placing links in the appropriate run level directories. The easy way to do this is to use the chkconfig command, as shown here:

# chkconfig --add hudson

And now, you should be good to go!

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