side load cgroups into Debian init scripts

gistfile1.sh

# put this fragment in a daemon's /etc/default/$NAME file to side-load
# putting that daemon into a cgroup automatically

ulimit -l unlimited

NOW=$(date +%s)
APPLICATION=$(basename $0 |sed -r -e 's/\.init$//' -e 's/-(dev|prod|staging|perf)$//')
INSTANCE=$(basename $0 |sed -r -e 's/\.init$//' -e 's/.*-(dev|prod|staging|perf)$/\1/')

# gross default that assumes unnamed instances are production
[ -n "$INSTANCE" -a "$INSTANCE" != "$APPLICATION" ] || INSTANCE="prod"

if [ -n "$APPLICATION" ] ; then
  CG="/cgroup/${APPLICATION}"
  if [ -n "$INSTANCE" ] ; then
    CG="$CG-${INSTANCE}"
  fi
  if [ -d /cgroup -a -e /cgroup/tasks ] ; then 
    mkdir -p $CG
    [ -n "$(cat $CG/cpuset.mems)" ] || cat /cgroup/cpuset.mems > $CG/cpuset.mems
    [ -n "$(cat $CG/cpuset.cpus)" ] || cat /cgroup/cpuset.cpus > $CG/cpuset.cpus
    # add this script's pid to tasks so subprocesses will be in the cg
    echo $$ > $CG/tasks
  fi
fi