Ubuntu upstart gets incorrect PID from Play 1.3

The Upstart script using the start-stop-daemon we've been using for Play 1.2.7 is now unable to stop/restart Play since Play 1.3 due to it having an incorrect PID.

Framework version: 1.3.0 on Ubuntu 12.04.5 LTS

Reproduction steps:

Setup an upstart script (playframework.conf) for a Play application
Play application starts successfully on server reboot Run 'sudo status playframework' will return playframework start/running, process 28912 - At this point process 28912 doesn't exist
vi {playapplicationfolder}/server.pid shows 28927
'stop playframework' then fails due to unknown pid 28912 'status playframework' results in playframework stop/killed, process 28912

Only way to restart play framework after this point is to either find the actual process and kill it then start play using the usual 'play start' command manually. Or restart the server.

This has broken our deployments scripts now as we used to install the new version of our app, then do play restart before reconnecting to the load balancer.

Upstart Script:

#Upstart script for a play application that binds to an unprivileged user.
# put this into a file like /etc/init/playframework
# you can then start/stop it using either initctl or start/stop/restart
# e.g. 
# start playframework

description     "PlayApp"
author          "-----"
version         "1.0"

env PLAY_BINARY=/opt/play/play
env JAVA_HOME=/usr/lib/jvm/java-7-openjdk-amd64
env HOME=/opt/myapp/latest
env USER=ubuntu
env GROUP=admin
env PROFILE=prod

start on (filesystem and net-device-up IFACE=lo) or runlevel [2345]
stop on runlevel [!2345]

limit nofile 65536 65536
respawn
respawn limit 10 5
umask 022
expect fork


pre-start script
        test -x $PLAY_BINARY || { stop; exit 0; }
        test -c /dev/null || { stop; exit 0; }
        chdir ${HOME}
        rm ${HOME}/server.pid || true
        /opt/configurer.sh
end script

pre-stop script
        exec $PLAY_BINARY stop $HOME
end script

post-stop script
        rm ${HOME}/server.pid || true
end script

script
exec start-stop-daemon --start --exec $PLAY_BINARY --chuid $USER:$GROUP --chdir $HOME -- start $HOME -javaagent:/opt/newrelic/newrelic.jar --%$PROFILE -Dprecompiled=true --http.port=8080 --https.port=4443
end script

We've tried specifying the PID file in the start-stop-daemon as per: http://man.he.net/man8/start-stop-daemon however this also didnt seem to have any effect.

I have found some threads on similar issues https://askubuntu.com/questions/319199/upstart-tracking-wrong-pid-of-process-not-respawning but have been unable to find a way round this so far. I have tried changing fork to daemon but the same issue remains. I also can't see what has changed between Play 1.2.7 and 1.3 to cause this.

Another SO post has also asked a similar question but not had an answer as yet: https://stackoverflow.com/questions/23117345/upstart-gets-wrong-pid-after-launching-celery-with-start-stop-daemon

Solution

This is because getJavaVersion() spawns a subprocess, which bumps the PID count, which breaks Upstart, the latter which expects Play to fork exactly none, once or twice, depending on which expect stanza you use.

I've fixed this in a pull request.