cron-lite.conf

# Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

description     "Spawns a dumb cron knockoff"
author          "chromium-os-dev@chromium.org"

# We have two scheduled tasks:
# - hourly crash reporter
# - daily log cleanup and rotation
# Instead of pulling in all of cron, we simply run a check every 5
# minutes to see if the last run file for a given task exceeds that
# tasks expected "deadline" to run in seconds. If it has, the task is
# run.  There is no support for de-duping or locking.  This means this
# shell script is not suitable for tasks that may overlap execution
# instances.
start on starting system-services
stop on stopping system-services

script

  SPOOL_DIR=/var/spool/cron-lite
  CHECK_DELAY=300  # 5 minutes
  LOGGER="logger -p local3.info -t $UPSTART_JOB"

  # comma separated fields, newline separated entries
  TASKS="
    3600,crash_sender,/sbin/crash_sender
    86400,cleanup_logs,/usr/sbin/chromeos-cleanup-logs
  "

  # Exits successfully if rotation is needed.
  should_run() {
    local name="$1"
    local delay="$2"
    local file="$SPOOL_DIR/$name"

    if [ ! -e $file ]; then
      touch $file
    fi
    local last_rotation=$(stat -c "%Y" $file 2>/dev/null || echo 0)
    local now=$(date +%s)
    local time_diff=$((now - last_rotation))

    [ $time_diff -lt $delay ] && return 1
    $LOGGER "$name needs to be run: $time_diff >= $delay"
    return 0
  }

  $LOGGER "cleanup main loop started."
  trap "$LOGGER 'exiting'" EXIT

  # Avoid weird spool paths if possible
  test -L /var/spool && unlink /var/spool
  test -L $SPOOL_DIR && unlink $SPOOL_DIR
  mkdir -p $SPOOL_DIR
  if [ ! -O $SPOOL_DIR -o ! -d $SPOOL_DIR ]; then
    $LOGGER "Spool directory is damaged. Aborting!"
    exit 1
  fi

  while true; do
    # Allow the sleep to be killed manually without terminating the handler.
    sleep $CHECK_DELAY || true
    printf "$TASKS" | while read task; do
      delay=$(echo $task | cut -f1 -d,)
      name=$(echo $task | cut -f2 -d,)
      script=$(echo $task | cut -f3 -d,)
      if [ -z "$name" ]; then
       continue
      fi
      if should_run $name $delay; then
        rm "$SPOOL_DIR/$name" || true
        touch "$SPOOL_DIR/$name"
        $LOGGER "running $script for $name"
        (sh -c "$script" || true; $LOGGER "$name completed") &
      fi
    done
  done

end script