DayZ Linux Server watchdog

README.md

DayZ Linux Server watchdog

This DayZ Watchdog script to check server availability

With the release of DayZ 1.24, a server for Linux appeared, this is undoubtedly very cool, but the implementation was in an experimental state for a very long time, which is why some problems crop up when trying to run modified community servers.

At the time of writing, there was a problem with the scheduled restart of the modified server based on an event from messages.xml. Details at https://feedback.bistudio.com/T179734

Important

These are instructions for a non-system user; for a root user you can adapt them yourself if necessary

Setup

Note

List of system utilities required for work, make sure that all are available on your system
nc, stat, grep (GNU), date, systemctl, cut, sleep

Setup script

mkdir -p ~/.local/bin/
curl -#SfLo ~/.local/bin/dayz-watchdog \
  https://gist.githubusercontent.com/WoozyMasta/3c3aaf8d1b1517e9ee47c6b2a96fee96/raw/dayz-watchdog
chmod +x ~/.local/bin/dayz-watchdog

Let's check that ~/.local/bin is in PATH and if not add it

[[ ":$PATH:" != *":$HOME/.local/bin:"* ]] && \
  printf '\n#[ -d "$HOME/.local/bin" ] && PATH="$HOME/.local/bin:$PATH"\n' >> ~/.profile

Let's run it once, as arguments we pass all the names of systemd services that we will check

dayz-watchdog dayz-server.service

Schedule run script

Download systemd service and timer

mkdir -p ~/.config/systemd/user/
curl -#SfLo ~/.config/systemd/user/dayz-watchdog.service \
  https://gist.githubusercontent.com/WoozyMasta/3c3aaf8d1b1517e9ee47c6b2a96fee96/raw/dayz-watchdog.service
curl -#SfLo ~/.config/systemd/user/dayz-watchdog.timer \
  https://gist.githubusercontent.com/WoozyMasta/3c3aaf8d1b1517e9ee47c6b2a96fee96/raw/dayz-watchdog.timer

Edit arguments in ExecStart= property

editor ~/.config/systemd/user/dayz-watchdog.service

Edit scheduller in OnCalendar= property, default is every minute

editor ~/.config/systemd/user/dayz-watchdog.service

Enable and start timer

systemctl --user daemon-reload
systemctl --user start dayz-watchdog.timer
systemctl --user enable dayz-watchdog.timer
systemctl --user status dayz-watchdog.service
journalctl --user -eu dayz-watchdog

dayz-watchdog

#!/usr/bin/env bash
# DayZ watchdog
# issue: https://feedback.bistudio.com/T179734
# required: nc stat grep date systemctl cut sleep
# place in: .local/bin/dayz-watchdog
# usage: dayz-watchdog dayz-server@1 dayz-server@2 dayz-server@3 dayz-server@4

set -euo pipefail

[ $# -eq 0 ] && { >&2 echo "Need pass servce names as args"; exit 1; }

watchtime=$(date +%s)

check() {
  local unit="$1" pid port
  pid="$(systemctl --user show "$unit" --property MainPID | cut -d= -f2)"

  # Skip PIDs younger than 5 minutes
  [ "$(( watchtime - "$(stat -c %Y "/proc/$pid")" ))" -le 300 ] && return 0

  port=$(grep -aoP -- '-port=\K\d+' "/proc/$pid/cmdline")
  if ! nc -vzu 127.0.0.1 "$port" 2>/dev/null; then
    # One more try
    nc -vzu 127.0.0.1 "$port" 2>/dev/null && return 0

    # As tests have shown, SIGHUP will correctly terminate a frozen process
    kill -s HUP "$pid"
    >&2 echo "DayZ service: $unit PID: $pid stopped by watchdog"

    # Wait 30 seconds for completion, otherwise we kill forcibly
    for (( i=0; i<30; i++ )); do
      [ ! -d "/proc/$pid/" ] && return 0
      sleep 1s
    done

    [ -d "/proc/$pid/" ] && kill -9 "$pid"
    >&2 echo "DayZ service: $unit PID: $pid killed by watchdog"
  fi
}

for unit in "$@"; do
  # run only for runing services
  systemctl --user is-active --quiet "$unit" && check "$unit" &
done

wait

dayz-watchdog.service

# .config/systemd/user/dayz-watchdog.service

[Unit]
Description=Watchdog DayZ Server
Wants=dayz-watchdog.timer

[Service]
Type=oneshot
ExecStart=/home/ts4ta/.local/bin/dayz-watchdog dayz-server@1 dayz-server@2 dayz-server@3 dayz-server@4 dayz-server@5

[Install]
WantedBy=default.target

dayz-watchdog.timer

# .config/systemd/user/dayz-watchdog.timer

[Unit]
Description=Watchdog DayZ Server
Requires=dayz-watchdog.service

[Timer]
Unit=dayz-watchdog.service
Persistent=true
OnCalendar=*-*-* *:*:00

[Install]
WantedBy=timers.target