A simple daemon script that I used for debugging running Docker containers in AWS ECS.

README.md

Outputs

{"name": "worker", "level": "INFO", "message": "Service start", "timestamp": "2023-04-05 14:04:48.974687279", "ip": "172.17.0.2", "pid": 7}
{"name": "worker", "level": "INFO", "message": "ping", "timestamp": "2023-04-05 14:04:48.975945036", "ip": "172.17.0.2", "pid": 7}
{"name": "worker", "level": "INFO", "message": "Received signal: SIGTERM", "timestamp": "2023-04-05 14:04:53.979013322", "ip": "172.17.0.2", "pid": 7}
{"name": "worker", "level": "INFO", "message": "Stopping", "timestamp": "2023-04-05 14:04:53.980930837", "ip": "172.17.0.2", "pid": 7}

runworker.sh

#!/usr/bin/env bash
set -e

IP=$(hostname -I | awk '{print $1}')
SLEEP_INTERVAL=5
PID=$$

print_log() {
  printf \
    '{"name": "worker", "level": "%s", "message": "%s", "timestamp": "%s", "ip": "%s", "pid": %d}\n' \
    "$1" "$2" \
    "$(date "+%Y-%m-%d %H:%M:%S.%N")" \
    "${IP}" \
    "${PID}"
}

trap 'print_log "INFO" "Received signal: $1" && print_log "INFO" "Stopping"; exit' SIGINT SIGTERM

print_log "INFO" "Service start"

while true; do
  print_log "INFO" "ping"

  sleep "${SLEEP_INTERVAL}"
done