strace-hook.sh

strace-hook.sh

#!/bin/bash
# ./strace-hook.sh update-status
# this command straces all the processes and subprocesses spawned
# by a particular juju hook when is run.

set -e

hook=${1:-update-status}
regex=".*${hook}.*"
trace_dir=${2:-trace}

if [ ! -e ${trace_dir} ]; then
   mkdir ${trace_dir}
fi

function ctrl_c() {
    killall -9 strace && exit 0;
}

function monitor() {
    while true; do
        pids=""
        for f in $(grep -irl ${regex} /proc/*/cmdline | grep -v self); do
	    pids+=$(echo $(basename $(dirname $f)) | awk '{print" -p "$1}')
        done
        if [ -n "$pids" ]; then
	    strace $pids -ff -t -o ${trace_dir}/strace
        fi
        sleep .5
    done
}

trap ctrl_c INT
monitor