How to manage running multiple branchs of LMS git code

[gharris999]

This is a proposed wiki how-to. I thought I'd roll it out here first to elicit comments. Anyone please chime in here. If I receive positive feedback, I'll author a wiki page on this topic.

Goal:

Using minimal download bandwidth and a minimal on-disc footprint, allow one to run any branch of squeezeboxserver / logitechmediaserver from 7.0 to 7.8 as a service and to easily allow switching between installed branches.

This is potentially useful to plugin writers who often need to test compatibility with various sbs/lms versions.

Assumptions:

• Running on Ubuntu or some debian based distro.
• Service will run under the user account 'lms'.
• Local git repository will reside at /usr/share/lms/server.
• We'll create separate data and log directories for any branch we're going to run.
• Those data and log dirs will be at /var/lib/lms_data/${BRANCHNAME} and /var/log/lms_log/${BRANCHNAME}
• Those data and log dirs will be linked to /var/lib/lms and /var/log/lms
• We'll create a generic 'lms' service for running the code.
• We'll make updating the repo a service control option.
• We'll have a script for easily switching between branches.

So, for example, say we're running the lms 7.8.x git code. Switching to SqueezeCenter 7.3.x would be as easy as:

# /usr/local/sbin/lms-switch-branch.sh 7.3

Also, for example, updating the currently running branch to the latest code and discarding any local changes would be as easy as:

# service lms force-update

Preparation:

Become root

sudo su

Create the lms user account:

useradd --gid nogroup --no-create-home --no-user-group --system --shell /bin/false "lms"

Download the latest version of the repo:

git clone -n --depth 1 https://github.com/Logitech/slimserver.git /usr/share/lms/server

Note: by downloading only the latest revisions for every branch, we keep the downloaded object file to about 250M. Remove the "--depth 1" from that command to make previous revisions available.

Checkout branch 7.8

cd /usr/share/lms/server
git checkout 7.8

Create data and log dirs for the 7.8 branch

mkdir -p /var/lib/lms_data/7.8
chown -R lms:nogroup /var/lib/lms_data
mkdir -p /var/log/lms_log/7.8
chown -R lms:nogroup /var/log/lms_log

Create links to the data and log dirs..

ln -s /var/lib/lms_data/7.8  /var/lib/lms
ln -s /var/log/lms_log/7.8 /var/log/lms

Create a defaults file for the service..
/etc/default/lms:

SLIMDESC='LMS branch 7.8 git code'
SLIMUSER='lms'
SLIMOPTIONS=''

Create a service control script..
/etc/init.d/lms:

#!/bin/sh

### BEGIN INIT INFO
# Provides:          	lms
# Required-Start:    	$all
# Required-Stop:     	$all
# Should-Start:      	$all
# Should-Stop:       	$all
# Default-Start:     	2 3 4 5
# Default-Stop:      	0 1 6
# Short-Description:	Startup script for the LMS Media Server git code
# Description:		LMS Media Server git code powers the Squeezebox, Transporter and SLIMP3 network music
#				players and is the best software to stream your music to any software MP3
#				player. It supports MP3, AAC, WMA, FLAC, Ogg Vorbis, WAV and more!
#				As of version 7.7 it also supports UPnP clients, serving pictures and movies too!
### END INIT INFO


#
# $Id$
#
# lms initscript for slimserver.pl
# This file should be placed in /etc/init.d.
#
# Original Author: Mattias Holmlund
# Updated By: Dan Sully, Michael Herger
#
# Rewrite 20120515 by Gordon Harris to make conforming with:
# http://refspecs.linuxbase.org/LSB_4.0.0/LSB-Core-generic/LSB-Core-generic/iniscrptact.html
# and based on http://www.thegeekstuff.com/2012/03/lsbinit-script/
#

# Using the lsb functions to perform the operations.
. /lib/lsb/init-functions

SLIMSRVC='lms'
SLIMUSER='lms'
SLIMGROUP=$(id -ng $SLIMUSER)
SLIMDESC='LMS Media Server git code'
REPO=/usr/share/$SLIMSRVC/server
DAEMON=/usr/share/$SLIMSRVC/server/slimserver.pl
DAEMON_SAFE=/usr/sbin/${SLIMSRVC}_safe
PIDFILE=/var/run/${SLIMSRVC}.pid
SCRIPTNAME=$(basename /etc/init.d/${SLIMSRVC})
PREFSDIR=/var/lib/${SLIMSRVC}/prefs
LOGDIR=/var/log/${SLIMSRVC}/
CACHEDIR=/var/lib/${SLIMSRVC}/cache
CHARSET=utf8
SLIMOPTIONS=

# Read config file if it is present.
if [ -r /etc/default/${SLIMSRVC} ]; then
	. /etc/default/${SLIMSRVC}
fi

d_check_running() {
	if [ -e $PIDFILE ]; then
		status_of_proc -p $PIDFILE $DAEMON "$SLIMDESC" > /dev/null 2>&1 && status=0 || status=$?
		if [ $status -eq 0 ]; then
			log_daemon_msg "$SLIMDESC is already running"
			log_end_msg 0
			exit 0
		fi
	fi
}

d_start() {
	d_check_running

	log_daemon_msg "Starting" "$SLIMDESC"

	# Use lms_safe to restart the daemon when
	# it dies. This must be done to handle mysql restarts.
	if start-stop-daemon --start --quiet \
		--chuid $SLIMUSER \
		--pidfile $PIDFILE \
		--exec $DAEMON_SAFE \
		--background \
		--make-pidfile \
		-- \
		$DAEMON \
		--prefsdir $PREFSDIR \
		--logdir $LOGDIR \
		--cachedir $CACHEDIR \
		--charset=$CHARSET \
		$SLIMOPTIONS ; then
		log_end_msg 0
	else
		log_end_msg 1
	fi
}

# This starts lms without the safe script..
d_start_direct() {
	d_check_running

	log_daemon_msg "Starting" "$SLIMDESC"

	# Make the pid file writeable by lms
	touch $PIDFILE
	chown "${SLIMUSER}:${SLIMGROUP}" $PIDFILE

	if start-stop-daemon --start --quiet \
		--chuid $SLIMUSER \
		--pidfile $PIDFILE \
		--exec $DAEMON \
		--background \
		--make-pidfile \
		-- \
		--pidfile $PIDFILE \
		--prefsdir $PREFSDIR \
		--logdir $LOGDIR \
		--cachedir $CACHEDIR \
		--charset=$CHARSET \
		$SLIMOPTIONS ; then
		log_end_msg 0
	else
		log_end_msg 1
	fi
}

d_stop() {
	if [ -e $PIDFILE ]; then
		status_of_proc -p $PIDFILE $DAEMON "$SLIMDESC" > /dev/null 2>&1 && status=0 || status=$?
		if [ $status -eq 0 ]; then
			log_begin_msg "Stoppping $SLIMDESC"
			start-stop-daemon --oknodo --stop --quiet --pidfile $PIDFILE --retry=TERM/30/KILL/5
			/bin/rm -rf $PIDFILE
			log_end_msg 0
		fi
	else
		# status 3: program is not running
		status=3
	fi

	if [ $status -gt 0 ]; then
		# status 1: program is dead and /var/run pid file exists
		log_daemon_msg "$SLIMDESC is not running"
	fi
}

#
#	Function that sends a SIGHUP to the daemon/service.
#
d_reload() {
	start-stop-daemon --stop --quiet --pidfile $PIDFILE --signal 1
}

d_status() {
	if [ -e $PIDFILE ]; then
		status_of_proc -p $PIDFILE $DAEMON "$SLIMDESC" && exit 0 || exit $?
	else
		log_daemon_msg "${SLIMDESC} is not running"
		cd "$REPO" && in_repo
		log_daemon_msg "Getting ${SLIMDESC} repository status.."
		git remote show origin
		git status
		log_end_msg 3
	fi
}

in_repo(){
	if [ $(pwd) != "$REPO" ]; then
		log_daemon_msg "Error: ${REPO} not found."
		log_end_msg 3
		exit 128
	fi
}

d_update() {
	log_daemon_msg "Updating $SLIMDESC"
	cd "$REPO" && in_repo
	git pull && status=0 || status=$?
	if [ $status -eq 0 ]; then
		log_daemon_msg "${SLIMDESC} has ben updated."
	else
		log_daemon_msg "Error updating ${SLIMDESC}."
	fi
}

d_force_update() {
	log_daemon_msg "Force-Updating $SLIMDESC"
	cd "$REPO" && in_repo
	git reset --hard
	git clean -fd
	git pull && status=0 || status=$?
	if [ $status -eq 0 ]; then
		log_daemon_msg "${SLIMDESC} has ben updated."
	else
		log_daemon_msg "Error updating ${SLIMDESC}."
	fi
}

if [ ! -x "$DAEMON" ]; then
	log_daemon_msg "${DAEMON} not found."
	log_end_msg 5
	exit 5
fi

if [ ! -x "$DAEMON_SAFE" ]; then
	log_daemon_msg "${DAEMON_SAFE} not found."
	log_end_msg 5
	exit 5
fi


case "$1" in
  start)
	d_start
	;;
  start-direct)
	d_start_direct
       ;;
  stop)
	d_stop
	;;
#  reload)
#	d_reload
#	;;
  restart|force-reload)
	d_stop
	sleep 3
	d_start
	;;
  update)
	d_stop
	sleep 3
	d_update
	sleep 3
	d_start
       ;;
  force-update)
	d_stop
	sleep 3
	d_force_update
	sleep 3
	d_start
       ;;
  status)
       d_status
	;;
  *)
	log_action_msg "Usage: $(which service) $(basename $0) {start|stop|restart|force-reload|update|force-update|status}"
	exit 2
	;;
esac

exit $?

Create a service safe script..
/usr/sbin/lms_safe:

#!/bin/bash

# $Id$

if [ $# = 0 ]
then
  echo "To stop Logitech Media Server git code, kill this script instead of the"
  echo "actual lms process."
  echo
  echo "Usage: $0 lms-binary lms-arguments"
  exit 1
fi

function clean_up {
  # Kill the daemon if it is running
  kill $SLIMPID
  echo $(date "+%F %H:%M:%S") $(basename $0) "stopped." >> /var/log/lms/server.log
  exit
}

trap clean_up SIGINT SIGHUP SIGTERM

echo $(date "+%F %H:%M:%S") $(basename $0) "started." >> /var/log/lms/server.log


while true
do
  # From the Bash Reference Manual:
  # When Bash receives a signal for which a trap has been set 
  # while waiting for a command to complete, the trap will not 
  # be executed until the command completes. When Bash is waiting
  # for an asynchronous command via the wait builtin, the reception
  # of a signal for which a trap has been set will cause the wait
  # builtin to return immediately with an exit status greater than
  # 128, immediately after which the trap is executed.

  "$@" --norestart > /dev/null 2>&1 &
  SLIMPID=$!
  
  # wait for the server to get started before wait()
  sleep 5
  
  wait $SLIMPID
  echo $(date "+%F %H:%M:%S") "Logitech Media Server git code died. Restarting." >> /var/log/lms/server.log

  # Normally, when the server realizes that the mysql-connection is gone,
  # the mysql server has already been started again. So no need to sleep
  # here.

done

..to be continued..

[gharris999]

..continued.


Create a log rotate script..
/etc/logrotate.d/lms:

/var/log/lms/server.log {
  weekly
  rotate 5
  size 200k
  compress
  missingok

  postrotate
    # send USR1 to squeezebox PID to reset logging
    /bin/kill -USR1 `pgrep -f 'perl.*slimserver.pl' -n 2>/dev/null` 2>/dev/null || :
  endscript
}

/var/log/lms/scanner.log {
  weekly
  rotate 5
  size 200k
  compress
  missingok
}

Create service control links:

update-rc.d -f lms remove >/dev/null 2>&1
update-rc.d -f lms defaults

Create a branch switching script:
/usr/local/sbin/lms-switch-branch.sh

#!/bin/sh

NEWBRANCH='7.8'
ISGOODBRANCH=0
#Discard local changes...
DISCARD=0
#Update repo
UPDATE=0

if [ ! -z "$1" ]; then
  NEWBRANCH="$1"
fi

# Change to the repo dir..
cd /usr/share/lms/server

# Get a list of the available branches..
BRANCHES=`git branch -r | sed -n -e 's#^.*origin/\(.*\)$#\1#p'`

for BRANCH in $BRANCHES
do
  if [ "$NEWBRANCH" = "$BRANCH" ]; then
    ISGOODBRANCH=1
  fi
done

if [ $ISGOODBRANCH -lt 1 ]; then
  echo "Error: ${NEWBRANCH} is not a branch of github.com/Logitech/slimserver.git"
  echo "Available branches:"
  echo $BRANCHES
  exit 1
fi

# Stop the service..
service lms stop

# Do a hard reset of the repo to discard any local changes..
if [ $DISCARD -gt 0 ]; then
    git reset --hard
    git clean -fd
fi

# Switch to the new branch
git checkout "$NEWBRANCH"

if [ $? -gt 0 ]; then
  echo "Error checking out branch ${NEWBRANCH}."
  exit 1
fi

# Update the default file with the name of the new branch
RE="s/^SLIMDESC=.*$/SLIMDESC='LMS branch ${NEWBRANCH} git code'"
sed -i -e "$RE" /etc/default/lms

# Update the repo
if [ $UPDATE -gt 0 ]; then
  git pull
fi

# Create new data & log dirs..
LIBDIR="/var/lib/lms_data/${NEWBRANCH}"
LOGDIR="/var/log/lms_log/${NEWBRANCH}"

if [ ! -d "$LIBDIR" ]; then
  mkdir -p "$LIBDIR"
fi

if [ ! -d "$LOGDIR" ]; then
  mkdir -p "$LOGDIR"
fi

# Fix permissions
chown -r lms:nogroup "$LIBDIR"
chown -r lms:nogroup "$LOGDIR"

# Create new data & log links
LIBDIRLINK='/var/lib/lms'
LOGDIRLINK='/var/log/lms'


if [ -L "$LIBDIRLINK" ]; then
  rm "$LIBDIRLINK"
fi

if [ ! -d "$LIBDIRLINK" ]; then
  ln -s "$LIBDIR" "$LIBDIRLINK" 
fi

if [ -L "$LOGDIRLINK" ]; then
  rm "$LOGDIRLINK"
fi

if [ ! -d "$LOGDIRLINK" ]; then
  ln -s "$LOGDIR" "$LOGDIRLINK" 
fi

# Restart the service..
service lms start
exit $?

Script for running the git code from the console in debug mode:
lms-git-debug.sh

#!/bin/bash
# Script to debug running of lms git code..

#RUNASROOT=1
RUNASROOT=0

INSTNAME='lms'
INSTUSER='lms'

PIDFILE=/var/lib/${INSTNAME}/${INSTNAME}.pid
PREFSDIR=/var/lib/${INSTNAME}/prefs
LOGDIR=/var/log/${INSTNAME}
CACHEDIR=/var/lib/${INSTNAME}/cache
PUSER=${INSTUSER}
PGROUP=`id -ng $PUSER`
OUTFILE=./${INSTNAME}-git-debug.txt

if [ -e ${PIDFILE} ]; then
  rm ${PIDFILE}
fi

echo "Attempting to start ${INSTNAME}.."
echo "  Console output redirected to ${OUTFILE}.."
echo "  Hit CTRL+C to terminate.."

if [[ $RUNASROOT -eq 1 ]]; then
  /usr/bin/perl /usr/share/${INSTNAME}/server/slimserver.pl --pidfile=${PIDFILE} --user=${PUSER} --group=${PGROUP} --cachedir=${CACHEDIR} --prefsdir=${PREFSDIR} --logdir=${LOGDIR} --charset=utf8 --diag --d_startup >${OUTFILE} 2>&1
else
  sudo -u ${INSTUSER} /usr/bin/perl /usr/share/${INSTNAME}/server/slimserver.pl --pidfile=${PIDFILE} --cachedir=${CACHEDIR} --prefsdir=${PREFSDIR} --logdir=${LOGDIR} --charset=utf8 --diag --d_startup >${OUTFILE} 2>&1
fi

rm ${PIDFILE}

echo "Done!  Examine ${OUTFILE} for details.."

That's it for now. Mostly, I'm looking for comments here on the advisability of this approach.

[gharris999]

Ok, I've put together an install script that automates all the above steps, installing a 'lms' service which runs the logitechmediaserver git code. I've tested this script with Ubuntu 12.04 and Fedora 16. On Ubuntu (and other debian systems) the script installs a regular sysv-style init script. On Fedora and other distros using systemd, the script installs unit files.