initial commit

README.md

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+# signal-monitoring
+
+This program is for simple server monitoring and notifications with signal-cli.
+It's goal is to be able to run on supersimple servers, like NAS, raspberry pi,
+home routers, etc.
+
+## Setup
+
+First, install and configure [signal-cli](https://github.com/AsamK/signal-cli)
+(or replace script in notify function for different kind of notification).
+
+Then modify script and configure your sending number, recipient number and
+optionally path to java. I add PATH to signal-cli and java commands as well.
+
+Then at the bottom of the script, configure ping checks and URL string match
+checks.
+
+check_ping takes one argument, which is the name of the server
+
+check_url takes three arguments: "check identificator" (can be anything recognizable that can be a part of filename, such as hostname), URL and string to look for on the web page.
+
+The last signal-cli command just downloads all messages for this instance and
+drops them. Use this if this script is the only user using this server to
+ease up storage requirements for signal servers and make sure that it does not
+store too much (encrypted) messages for you.
+
+## Cron
+
+Run it from cron or task scheduler of your OS. Please refer to the documentation
+of your OS.
+
+## Why this project
+
+I wanted to be able to perform a simple monitoring for my hosted server from
+my home NAS. Signal is what I read, so e-mail notifications won't do it,
+I don't read e-mail that often.
+
+The script sends one notification per hour, if the service is consistently down.
+When it goes up again, it sends up notification.
+
+## If you liked this script, donate
+
+If you like this script, [support me by sending a small donation](https://juraj.bednar.io/en/support-me/)

signal-monitoring.sh

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+#!/bin/bash
+# if you need to add something to path:
+#PATH=$PATH:/path/to/java:/path/to/signal-cli
+# for some cases you should explicitly specify JAVA_HOME in
+# order for signal-cli to work
+#export JAVA_HOME=/var/packages/Java8/target/j2sdk-image/jre
+
+# username of the sending entity (phone number in international format)
+SIGNAL_USER="+1123123123123"
+
+# phone number of the user that receives the notification
+NOTIFY_NUMBER="+132132132132"
+
+# now go to the bottom of the script and specify the checks
+
+mkdir -p ~/.signal-monitoring && cd ~/.signal-monitoring
+
+function log {
+	echo "$1" >> ~/.signal-monitoring/log
+}
+
+# arguments: notify_text
+function notify {
+	echo $1 | signal-cli -u ${SIGNAL_USER} send $NOTIFY_NUMBER
+	log "Sending notification ${1}"
+}
+
+# arguments: check_name description
+function check_passed {
+	check_name=$1
+	description=$2
+	check_filename="${check_name}-error"
+
+	log "check_passed ${check_name} ${description}"
+
+	if [ -f ${check_filename} ]
+		then
+			rm -f $check_filename
+			notify "${description}"
+		fi
+}
+
+# arguments: check_name description
+function check_failed {
+	check_name=$1
+	description=$2
+	check_filename="${check_name}-error"
+
+	log "check_failed ${check_name} ${description}"
+
+	FOUND=`find ~/.signal-monitoring -mmin -60 -name ${check_name}-error -not -empty -print`
+	if [ -z "$FOUND" ]
+	  then # we don't have recent notification (60 minutes)
+		echo "${description}" > "${check_filename}"
+		notify "${description}"
+	  fi
+}
+
+
+# argument: hostname
+function check_ping {
+		server=$1
+		if ping -c 5 -q $server > /dev/null 2>&1
+			then
+				check_passed ${server}-ping "${server} ping is up"
+			else
+				check_failed ${server}-ping "${server} ping is not responding"
+			fi
+}
+
+# arguments: check_name url content_to_look_for
+function check_url {
+		check_name=$1
+		url=$2
+		content_to_look_for=$3
+		if wget -q -O - "$url" | grep "$content_to_look_for" > /dev/null 2>&1
+			then
+				check_passed ${check_name}-url "${check_name} UP: ${url} now contains ${content_to_look_for}"
+			else
+				check_failed ${check_name}-url "${check_name} DOWN: ${url} does not contain ${content_to_look_for}"
+			fi
+}
+
+# here are the checks
+
+# check pings
+check_ping my-first.server.com
+check_ping my-second.server.com
+
+check_url my-first.server.com "https://my-first.server.com/url/index.html" "Welcome to My First Server"
+check_url my-third.server.com "https://my-third.server.com/index.html" "Welcome to My Third Server"
+
+# Leave this if you don't use signal-cli outside of this script,
+# otherwise comment out, see readme
+signal-cli -u $SIGNAL_USER receive > /dev/null 2>&1