diff --git a/fhem/contrib/98_systemd_watchdog.pm b/fhem/contrib/98_systemd_watchdog.pm
new file mode 100644
index 000000000..30b7dd14b
--- /dev/null
+++ b/fhem/contrib/98_systemd_watchdog.pm
@@ -0,0 +1,343 @@
+###############################################################################
+#
+# Copyright notice
+#
+# (c) 2018 Alexander Schulz
+#
+# This script is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# The GNU General Public License can be found at
+# http://www.gnu.org/copyleft/gpl.html.
+# A copy is found in the textfile GPL.txt and important notices to the license
+# from the author is found in LICENSE.txt distributed with these scripts.
+#
+# This script is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# This copyright notice MUST APPEAR in all copies of the script!
+#
+###############################################################################
+
+# $Id$
+
+package main;
+
+use strict;
+use warnings;
+use POSIX;
+use Time::HiRes qw(gettimeofday);
+use Socket;
+
+sub watchdog_client_NotifySystemD($$);
+sub watchdog_client_Stop($);
+sub watchdog_client_Start($);
+sub watchdog_client_ProcessTimer(@);
+sub watchdog_client_IsWDAvailable($);
+
+sub systemd_watchdog_Initialize($) {
+ my ($hash) = @_;
+
+ # Consumer
+ $hash->{DefFn} = "watchdog_client_Define";
+ $hash->{UndefFn} = "watchdog_client_Undefine";
+ $hash->{ShutdownFn} = "watchdog_client_Shutdown";
+ $hash->{NotifyFn} = "watchdog_client_Notify";
+
+ #Log3($hash->{NAME},5,"Watchdog Client: Debug: watchdog_client_Initialize");
+ RemoveInternalTimer($hash);
+
+ return undef;
+}
+
+sub watchdog_client_IsWDAvailable($) {
+ my ( $hash ) = @_;
+ #return 1; # TODO XXX TEST
+ return defined($hash->{'.systemd'});
+}
+
+sub watchdog_client_Define($$) {
+ my ( $hash, $def ) = @_;
+ #Log3($hash->{NAME},5,"Watchdog Client: Debug: watchdog_client_Define");
+ my $name = $hash->{NAME};
+
+ # prevent multiple instances
+ my @devices = devspec2array("TYPE=watchdog_client");
+ foreach my $dev (@devices) {
+ if($dev ne $name) {
+ return "only one instance is allowed";
+ }
+ }
+
+ # remove old timer
+ RemoveInternalTimer($hash);
+
+ # check systemd watchdog available
+ my $sname = $ENV{NOTIFY_SOCKET};
+ if(defined($sname)) {
+ $hash->{'systemd-watchdog'}="available";
+ $hash->{'.systemd'}=1;
+ Log3($hash->{NAME},4,"Watchdog Client: systemd-watchdog available. starting watchdog client");
+ } else {
+ $hash->{'systemd-watchdog'}="not available";
+ $hash->{'.systemd'}=undef;
+ Log3($hash->{NAME},1,"Watchdog Client: systemd watchdog is not available. Module inactiv.");
+ }
+ # Initialize
+ watchdog_client_Start($hash);
+ return undef;
+}
+
+sub watchdog_client_Undefine($) {
+ my ($hash) = @_;
+ #Log3($hash->{NAME},5,"Watchdog Client: Debug: watchdog_client_Undefine");
+ # Clean up
+ watchdog_client_Stop($hash);
+ return undef;
+}
+
+sub watchdog_client_Shutdown($) {
+ my ($hash) = @_;
+ #Log3($hash->{NAME},5,"Watchdog Client: Debug: watchdog_client_Shutdown");
+ return undef unless defined $hash->{'.initialized'};
+ # Shutdown => Deaktivate watchdog
+ my $name = $hash->{NAME};
+ Log3($name,2,"Watchdog Client: Shutting down");
+ watchdog_client_Stop($hash);
+ return undef;
+}
+
+sub watchdog_client_Notify($$) {
+ my ($hash,$dev) = @_;
+ #Log3($hash->{NAME},1,"Watchdog Client: Debug: watchdog_client_Notify: --- ");
+ if( $dev->{NAME} eq "global" ) {
+ # if( grep(m/^INITIALIZED$/, @{$events}) ) {
+ # Log3($hash->{NAME},1,"Watchdog Client: Debug: watchdog_client_Notify: INITIALIZED");
+ # watchdog_client_Start($hash) unless defined $hash->{'.initialized'};
+ # return undef;
+ # } elsif( grep(m/^REREADCFG$/, @{$events}) ) {
+ # #
+ # return undef;
+ # }
+ if( grep(m/^(INITIALIZED|REREADCFG)$/, @{$dev->{CHANGED}}) ) {
+ #Log3($hash->{NAME},5,"Watchdog Client: Debug: watchdog_client_Notify: GLOBAL");
+ watchdog_client_Start($hash) unless defined $hash->{'.initialized'};
+ }
+ }
+}
+
+sub watchdog_client_ProcessTimer(@) {
+ my ($hash) = @_;
+ #Log3($hash->{NAME},5,"Watchdog Client: Debug: watchdog_client_ProcessTimer");
+ # Reset watchdog
+ watchdog_client_NotifySystemD($hash, "WATCHDOG=1\n");
+
+ my $sleep = $hash->{'sleep-time'};
+ $sleep = 30 unless defined $sleep;
+ my $now = gettimeofday();
+ my $next = int($now) + $sleep;
+ InternalTimer($next, 'watchdog_client_ProcessTimer', $hash, 0);
+ readingsSingleUpdate($hash,"next",FmtTime($next),1);
+}
+
+sub watchdog_client_Start($) {
+ my ($hash) = @_;
+ #Log3($hash->{NAME},5,"Watchdog Client: Debug: watchdog_client_Start");
+ unless ($main::init_done) {
+ return if $hash->{'.firsttime'};
+ watchdog_client_NotifySystemD($hash, "STATUS=starting\n");
+ watchdog_client_NotifySystemD($hash, "MAINPID=$$\n");
+ readingsSingleUpdate($hash,"state","starting",1);
+ $hash->{'.firsttime'}=1;
+ return;
+ }
+ return if $hash->{'.initialized'};
+
+ unless (watchdog_client_IsWDAvailable($hash)) {
+ Log3($hash->{NAME},2,"Watchdog Client: no systemd watchdog available");
+ readingsSingleUpdate($hash,"state","inactiv",1);
+ readingsSingleUpdate($hash,"next","none",1);
+ return;
+ }
+
+ my $sleep = ($ENV{WATCHDOG_USEC} // 120000000) / 4 / 1000000;
+ $hash->{'sleep-time'} = $sleep;
+ $hash->{'.initialized'} = 1;
+
+ my $next = int(gettimeofday()) + 1;
+ InternalTimer($next, 'watchdog_client_ProcessTimer', $hash, 0);
+
+ # System ready
+ watchdog_client_NotifySystemD($hash, "READY=1\n");
+ watchdog_client_NotifySystemD($hash, "MAINPID=$$\n");
+ watchdog_client_NotifySystemD($hash, "STATUS=started\n");
+
+ Log3($hash->{NAME},2,"Watchdog Client: initialized");
+ readingsSingleUpdate($hash,"state","active",1);
+}
+
+sub watchdog_client_Stop($) {
+ my ($hash) = @_;
+ #Log3($hash->{NAME},5,"Watchdog Client: Debug: watchdog_client_Stop");
+ watchdog_client_NotifySystemD($hash, "STOPPING=1\n");
+ watchdog_client_NotifySystemD($hash, "STATUS=stopping\n");
+ RemoveInternalTimer($hash);
+ $hash->{'.initialized'} = 0;
+ my $name = $hash->{NAME};
+ Log3($name,2,"Watchdog Client: deactivated");
+ readingsSingleUpdate($hash,"state","deactivated",1);
+}
+
+sub watchdog_client_NotifySystemD($$) {
+ my ($hash,$cmd) = @_;
+ #Log3($hash->{NAME},5,"Watchdog Client: Debug: watchdog_client_NotifySystemD: $cmd");
+ return unless defined $hash->{'.initialized'};
+ return unless watchdog_client_IsWDAvailable($hash);
+
+ my $name = $hash->{NAME};
+ #Log3($name,1,"Watchdog Client: notify systemd-watchdog: $cmd");
+
+ my $sname = $ENV{NOTIFY_SOCKET};
+ if(!defined($sname)) {
+ #watchdog_client_Stop($hash);
+ Log3($name,1,"Watchdog Client: NOTIFY_SOCKET not available. Please configure systemd-watchdog properly!");
+ return;
+ }
+
+ Log3($name,4,"Watchdog Client: notify systemd-watchdog: $cmd");
+ my $sock_addr = sockaddr_un($sname);
+ socket(my $server, PF_UNIX,SOCK_DGRAM,0);
+ connect($server, $sock_addr);
+ print $server $cmd;
+ close($server);
+}
+
+1;
+
+=pod
+=begin html_DE
+
+
+Systemd Watchdog Client
+
+
+ Systemd erlaubt Ueberwachung von Programmen mittels eines Watchdogs.
+ Sendet der Prozess innerhalnb eines definierten Interval kein 'Lebenszeichen',
+ wird dieser gestoppt und neu gestartet.
+ Dieses Modul sendet periodisch eine keep-alive Nachricht an das Systemd-Watchdog.
+
+
+ FHEM muss unter Kontrolle von Systemd laufen und Watchdog muss korrekt konfiguriert sein.
+ Folgendes Script kann benutzt werden:
+
+ [Unit]
+ Description=FHEM Home Automation
+ Requires=network.target
+ #After=network.target
+ After=dhcpcd.service
+
+ [Service]
+ Type=forking
+ NotifyAccess=all
+ User=fhem
+ Group=dialout
+ WorkingDirectory=/opt/fhem
+ ExecStart=/usr/bin/perl fhem.pl fhem.cfg
+ #ExecStart=/usr/bin/perl fhem.pl configDB
+ TimeoutStartSec=240
+ TimeoutStopSec=120
+ #ExecStop=/usr/bin/pkill -U fhem perl
+ ExecStop=/usr/bin/pkill -f -U fhem "fhem.pl fhem.cfg"
+ # Restart options: no, on-success, on-failure, on-abnormal, on-watchdog, on-abort, or always.
+ Restart=on-failure
+ RestartSec=3
+ WatchdogSec=180
+ PIDFile=/opt/fhem/log/fhem.pid
+
+ [Install]
+ WantedBy=multi-user.target
+
+ Das Script kann unter "/etc/systemd/system/fhem.service" angelegt werden.
+ Mit "sudo systemctl daemon-reload" wird sysgtemd-Konfiguration erneuert.
+ Anschliessend kann FHEM mit folgendem Befehl gestartet werden: "sudo systemctl start fhem.service".
+
+ Wenn in dem Script "Type=notify" verwendet wird, muss global Attribute "nofork=1" gesetzt sein.
+ Bei "Type=forking" muss in Script der korrekte Pfad zu dem PID-Datei angegeben werden,
+ diese Datei muss auch in FHEM mit dem global Attribute "pidfilename" aktiviert sein.
+
+
+
+ Define
+
+
+
+=end html_DE
+
+=begin html
+
+
+Systemd Watchdog Client
+
+
+ Systemd allows monitoring of programs by a watchdog.
+ If a process does not respond within a certain time interval, it will be stopped and restarted.
+ This module periodically sends keep-alive message to the systemd.
+
+
+ fhem must be started under control of systemd. Watchdog must be also configured properly.
+ You can use the following script:
+
+ [Unit]
+ Description=FHEM Home Automation
+ Requires=network.target
+ #After=network.target
+ After=dhcpcd.service
+
+ [Service]
+ Type=forking
+ NotifyAccess=all
+ User=fhem
+ Group=dialout
+ WorkingDirectory=/opt/fhem
+ ExecStart=/usr/bin/perl fhem.pl fhem.cfg
+ #ExecStart=/usr/bin/perl fhem.pl configDB
+ TimeoutStartSec=240
+ TimeoutStopSec=120
+ #ExecStop=/usr/bin/pkill -U fhem perl
+ ExecStop=/usr/bin/pkill -f -U fhem "fhem.pl fhem.cfg"
+ # Restart options: no, on-success, on-failure, on-abnormal, on-watchdog, on-abort, or always.
+ Restart=on-failure
+ RestartSec=3
+ WatchdogSec=180
+ PIDFile=/opt/fhem/log/fhem.pid
+
+ [Install]
+ WantedBy=multi-user.target
+
+ Create the script as "/etc/systemd/system/fhem.service".
+ Use "sudo systemctl daemon-reload" to reload systemd configuration.
+ Start fhem with: "sudo systemctl start fhem.service".
+
+ If you like to use Type=notify, you must set fhem global attribute nofork=1.
+ If you use Type=forking, please set fhem global pidfilename.
+
+
+
+ Define
+
+
+
+=end html
+=cut
+
+