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Keep a Server Script Running with Cron

I tried using PM2 and systemd to keep a Raspberry Pi server running. Neither worked consistently. Instead, I setup a much simpler cron task.

Cron setup​

Add the following to the top of crontab -e:

SHELL=/bin/bash
HOME=/home/<username>
BASH_ENV=$HOME/.bashrc

This fills up the environment for your cron tasks so that they can actually run stuff, like npm scripts.

* * * * * bash check-server.sh

check-server.sh is a simple script:

#!/bin/bash

# Get the directory of this script
SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
LOGFILE="/tmp/server.log"
# Whatever port your server runs on
PORT=3001

if ! lsof -i:"$PORT" >/dev/null 2>&1; then
  echo "$(date): Starting server..." > "$LOGFILE"
  nohup npm start >> "$LOGFILE" 2>&1 &
fi

Bonus: for external access, set up nginx as a reverse proxy:

location / {
    proxy_pass http://127.0.0.1:3001;
}