Force journalctl vacuum if less than 5M left on remarkable

Readme.md

Install instructions:

• copy rotate.timer and rotate.service to /etc/systemd/system
• copy rotate.sh to /opt/bin
• chmod +x /opt/bin/rotate.sh
• systemctl daemon-reload
• systemctl enable rotate.timer
• systemctl start rotate.timer

rotate.service

[Unit]
Description=rotate log files

[Service]
Type=oneshot
ExecStart=/opt/bin/rotate.sh || true

rotate.sh

#!/bin/bash
rotate(){
  local available=$(df /var/log/journal | tail -n1 | awk '{print $4}');
  local max=$((5 * 1024));
  if [ $available -lt $max ];then
    local logs=$(du -s /var/log/journal | awk '{print $1}');
    local possible=$(($logs + $available));
    if [ $possible -lt $max ]; then
      echo "Only $possible space available. Did not rotate";
      return 1;
    fi;
    local free=$(($possible - $max));
    echo "Rotating to free $free"
    journalctl --vacuum-size=$(($logs - $free));
    available=$(df /var/log/journal | tail -n1 | awk '{print $4}');
    if [ $available -lt $max ];then
      echo "Could not clear enough logs";
      return 1;
    fi;
  else
    echo "Nothing to do";
  fi;
  return 0;
}
main(){
  rotate;
  local rc=$?;
  unset -f main;
  unset -f rotate;
  exit $rc;
}
main;

rotate.timer

[Unit]
Description=Rotate logs every 15 minutes

[Timer]
OnCalendar=*:0/15

[Install]
WantedBy=timers.target