Systemd is the Cat's Pyjamas



I have been converting some of the startup scripts for my Open Identity Stack project to use systemd. Systemd is now available on Fedora, CentOS and Redhat - and is coming soon to Debian and Ubuntu (you can actually get it now in Debian testing).

What strikes me is how dead simple it is to create init services that just work.  Here is an example for openidm.service that leverages start/stop scripts that come with OpenIDM:




[Unit]
Description=OpenIDM
After=remote-fs.target nss-lookup.target

[Service]
Type=simple
ExecStart=/opt/ois/openidm/startup.sh
ExecStop=/opt/ois/openidm/shutdown.sh
User=fr
SuccessExitStatus=143

[Install]
WantedBy=multi-user.target
* The only tricky thing above is the SuccessExitStatus. For reasons that I do not fully understand, many Java based programs started with shell scripts will use that system exit code.

Copy the above to /etc/systemd/system/openidm.service and you are good to go:

systemctl start openidm.service
systemctl stop openidm.service
systemctl status openidm.service

To see the output use:

journalctl 

Scroll to the end by typing "G"


This service file was dead simple to write, and "it just works". Systemd takes care of tracking the process and any spawned children.

By way of constrast, I will leave you with the old openidm script that I spent considerable time hacking to get the correct start/stop behavior. I could never get this init script to reliably execute the shell scripts that came with OpenIDM.


#!/bin/sh
# chkconfig: 345 95 5
# description: start/stop openidm



# clean up left over pid files if necessary
cleanupPidFile() {
if [ -f $OPENIDM_PID_FILE ]; then
rm -f "$OPENIDM_PID_FILE"
fi
trap - EXIT
exit
}

JAVA_BIN={{java_home}}/bin/java

OPENIDM_HOME={{install_root}}/openidm
OPENIDM_USER={{fr_user}}
OPENIDM_PID_FILE=$OPENIDM_HOME/.openidm.pid
OPENIDM_OPTS="-Xmx1024m -Dfile.encoding=UTF-8"

cd ${OPENIDM_HOME}

# Set JDK Logger config file if it is present and an override has not been issued
if [ -z "$LOGGING_CONFIG" ]; then
if [ -r "$OPENIDM_HOME"/conf/logging.properties ]; then
LOGGING_CONFIG="-Djava.util.logging.config.file=$OPENIDM_HOME/conf/logging.properties"
else
LOGGING_CONFIG="-Dnop"
fi
fi


CLASSPATH="$OPENIDM_HOME/bin/*:$OPENIDM_HOME/framework/*"
START_CMD="nohup $JAVA_BIN $LOGGING_CONFIG $JAVA_OPTS $OPENIDM_OPTS \
-Djava.endorsed.dirs=$JAVA_ENDORSED_DIRS \
-classpath $CLASSPATH \
-Dopenidm.system.server.root=$OPENIDM_HOME \
-Djava.awt.headless=true \
org.forgerock.commons.launcher.Main -c $OPENIDM_HOME/bin/launcher.json > $OPENIDM_HOME/logs/server.out 2>&1 &"
case "${1}" in
start)
su $OPENIDM_USER -c "$START_CMD eval echo \$\! > $OPENIDM_PID_FILE"
exit ${?}
;;
stop)
./shutdown.sh > /dev/null
exit ${?}
;;
restart)
./shutdown.sh > /dev/null
su $OPENIDM_USER -c "$START_CMD eval echo \$\! > $OPENIDM_PID_FILE"
exit ${?}
;;
*)
echo "Usage: openidm { start | stop | restart }"
exit 1
;;


esac

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