graceful_rclone.sh

#!/bin/bash
set -Eeuo pipefail

# Set up console colors
YELLOW='\033[1;33m'
RED='\033[1;31m'
CLEAR='\033[0m'

msg() {
  echo >&2 -e "${YELLOW}${1-}${CLEAR}"
}
fatal() {
  echo >&2 -e "${RED}${1-}${CLEAR}"
}

TERMINATION_GRACE_SECONDS="${TERMINATION_GRACE_SECONDS:-600}"

rclone serve sftp --key "${HOME}/.ssh/id_rsa" --addr :8022 --authorized-keys "${HOME}/.ssh/authorized_keys" remote:path &
RCLONE_PID=$!

socat "TCP-LISTEN:2022,fork,reuseaddr" "TCP-CONNECT:127.0.0.1:8022" &
SOCAT_PID=$!

# validate startup
sleep 2
if ! (ps | grep -q "${SOCAT_PID}" > /dev/null && ps | grep -q "${RCLONE_PID}" > /dev/null); then
  fatal "Startup failed"
  kill -s SIGTERM "${SOCAT_PID}"
  kill -s SIGTERM "${RCLONE_PID}"
  exit 1
fi

do_shutdown() {
  msg "Refusing new connections"
  kill -s SIGTERM "${SOCAT_PID}"

  i=1
  while true
  do
    if ! pgrep "socat" > /dev/null; then
      msg "All clients disconnected"
      break
    fi

    if [ $i -ge "${TERMINATION_GRACE_SECONDS}" ]; then
        fatal "Forcefully shutting down"
      break
    fi

    msg "Waiting for clients to disconnect"
    sleep 1
    i=$(( i + 1 ))
  done

  kill -s SIGTERM "${RCLONE_PID}"
  exit 0
}

# wait for shutdown signal
trap do_shutdown SIGTERM
tail -f /dev/null & wait