Ubuntu Upstart job with java jar

This article covers setting up an Upstart Job on an Ubuntu 12.04 server. This upstart job will start/stop a program packaged in a jar file.

For lots of details on upstart you can go to http://upstart.ubuntu.com/cookbook/ [1]

Creating a jar file with a manifest

To make life easier I am going to install ant to use to compile the code and create the jar file.

> sudo apt-get install ant

Create the code

> cd > mkdir jar-test > cd jar-test > mkdir -p src/com/whiteboardcoder/hello > mkdir target > vi src/com/whiteboardcoder/hello/hw.java

Put this in the java file

package com.whiteboardcoder.hello; import java.util.Date; import java.util.TimeZone; import java.util.Locale; import java.text.DateFormat; import java.text.SimpleDateFormat; public class hw {    public static String getISO8601Now(){       DateFormat dateFormat = new SimpleDateFormat(                      "yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.US);       dateFormat.setTimeZone(                       TimeZone.getTimeZone("UTC"));       return dateFormat.format(new Date());    }    public static void main(String...args){       TimeZone tz = TimeZone.getTimeZone("UTC");       try{         while(true){           System.out.println(                "Hello World The UTC time in ISO 8601 format is "                             + hw.getISO8601Now());           Thread.sleep(2000);         }       }       catch(Exception e){       }    } }

Create build.xml file for the ant build

> vi build.xml

And place the following in it

<project default="main" basedir=".">    <target name="main">      <echo>Compiling code and creating Jar file</echo>      <javac srcdir="src"             destdir="target"        />      <jar basedir="target" destfile="HW.jar">         <manifest>             <attribute name="Main-Class" value="com.whiteboardcoder.hello.hw" />         </manifest>      </jar>    </target> </project>

Run the ant build and create the executable jar file

> ant

Now run the executable jar

> java -jar HW.jar

This will output the UTC time in ISO 8601 format every 2 seconds

I just wanted to create a simple program that would keep putting output out so that we could see that it started/stopped in the upstart job

Create the upstart job

I found a few sites giving suggestions on how to make an upstart job to run a java jar file.  http://stackoverflow.com/questions/12102270/run-java-jar-file-on-a-server-as-background-process [2] has an upstart job that I used (adjusted it a little) http://askubuntu.com/questions/162768/starting-java-processes-with-upstart [3] has a more complex upstart example.

Another site I used for some information on upstart stanzas is at http://upstart.ubuntu.com/wiki/Stanzas [4]

Now to the nitty gritty create the /etc/init/helloworld.conf

> sudo vi /etc/init/helloworld.conf

This is the contents of my upstart job

description "Hello World" author "Patman" start on runlevel [2345] stop on runlevel [!2345] #Respawn the process if it crashes #If it respawns more than 10 times in 5 seconds stop respawn respawn limit 10 5 expect fork script     cd /home/patman/jar-test     java -jar HW.jar > /var/log/HW-test.log 2>&1 end script

Save it and start it

> sudo start helloworld

Then look at the output being saved at /var/log/HW-test.log

> sudo start helloworld

Now tail the output file

> sudo tail -f /var/log/HW-test.log

To stop the program run the following

> sudo stop helloworld

If you tail the log you will see that it has stopped J

References

[1]        Upstart Intro, Cookbook and Best Practises

            http://upstart.ubuntu.com/cookbook/

                Accessed 01/2014

[2]        Run java jar file on a server as background process

            http://stackoverflow.com/questions/12102270/run-java-jar-file-on-a-server-as-background-process

                Accessed 01/2014

[3]        Starting java processes with Upstart

            http://askubuntu.com/questions/162768/starting-java-processes-with-upstart

                Accessed 01/2014

[4]        Upstart Stanza

            http://upstart.ubuntu.com/wiki/Stanzas

                Accessed 01/2014