Difference between revisions of "MQTT monitoring Daemon"
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{{!}} style="text-align: center; width: 60px;" {{!}} [[File:Logo Debian.png{{!}}60px{{!}}link=https://www.debian.org/{{!}}center{{!}}middle{{!}}frameless]] | {{!}} style="text-align: center; width: 60px;" {{!}} [[File:Logo Debian.png{{!}}60px{{!}}link=https://www.debian.org/{{!}}center{{!}}middle{{!}}frameless]] | ||
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<p class="mwt-heading" >An example of what's possible...</p> | <p class="mwt-heading" >An example of what's possible...</p> | ||
= Requirements: = | |||
* <code>apt install mosquitto-clients</code> | * <code>sudo apt install mosquitto-clients</code> | ||
* <code>apt install jq</code> | * <code>sudo apt install jq</code> | ||
= The systemd Service Unit = | |||
<code>/etc/systemd/system/MQTTmon.service</code> | <code>sudo vi /etc/systemd/system/MQTTmon.service</code> | ||
<syntaxhighlight lang="bash"> | <syntaxhighlight lang="bash" line="1"> | ||
[Unit] | [Unit] | ||
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* Any time you create or edit a service unit: | * Any time you create or edit a service unit: | ||
** <code>systemctl daemon-reload</code> | ** <code>sudo systemctl daemon-reload</code> | ||
** <code>systemctl restart MQTTmon.service</code> | ** <code>sudo systemctl restart MQTTmon.service</code> | ||
* Check on how it's going... | * Check on how it's going... | ||
** <code>systemctl status MQTTmon.service</code> | ** <code>sudo systemctl status MQTTmon.service</code> | ||
= The Script = | = The Script = | ||
<code>/usr/bin/MQTTmon</code> | <code>sudo vi /usr/bin/MQTTmon</code> | ||
<syntaxhighlight lang="bash"> | <syntaxhighlight lang="bash" line="1"> | ||
#!/bin/bash | #!/bin/bash | ||
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= Sending it messages = | = Sending it messages = | ||
In these examples, the machine (LXC) used for testng is named '''poop2''' | In these examples, the machine (an LXC) used for testng is named '''poop2''' | ||
* Telling it to shut down... | * Telling it to shut down... | ||
** <code>mosquitto_pub -h LXC-Mosquitto -t turd -m '{"Target":"poop2","Message": "It is time to DIE","Command":"DIE"}'</code> | ** <code>mosquitto_pub -h LXC-Mosquitto -t turd -m '{"Target":"poop2","Message": "It is time to DIE","Command":"DIE"}'</code> | ||
Latest revision as of 18:53, 14 April 2023
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An example of what's possible...
Requirements:
sudo apt install mosquitto-clientssudo apt install jq
The systemd Service Unit
sudo vi /etc/systemd/system/MQTTmon.service
[Unit]
Description=MQTT Monitoring Daemon
After=network.target
Requires=network.target
[Service]
Type=simple
User=root
ExecStart=/usr/bin/MQTTmon
Restart=always
[Install]
WantedBy=multi-user.target
- Any time you create or edit a service unit:
sudo systemctl daemon-reloadsudo systemctl restart MQTTmon.service
- Check on how it's going...
sudo systemctl status MQTTmon.service
The Script
sudo vi /usr/bin/MQTTmon
#!/bin/bash
BROKER="LXC-Mosquitto"
TOPIC="turd"
MQTT=`/usr/bin/mosquitto_sub -C 1 -h $BROKER -t $TOPIC`
TARGET=`echo $MQTT {{!}} jq '.Target'`
MESSAGE=`echo $MQTT {{!}} jq '.Message'`
COMMAND=`echo ${MQTT} {{!}} jq '.Command'`
HOST=\"`hostname`\"
if [[ $TARGET == $HOST ]]
then
/root/Logit $TARGET , $COMMAND , $MESSAGE
if [[ $COMMAND == "\"MSG\"" ]] ; then
/root/Logit "Message is: " $MESSAGE
fi
if [[ $COMMAND == "\"WALL\"" ]] ; then
wall -n $MESSAGE
fi
if [[ $COMMAND == "\"DIE\"" ]] ; then
shutdown
fi
else
/root/Logit $TARGET " got a message too, but this is " $HOST " so we don't GAF."
fi
Sending it messages
In these examples, the machine (an LXC) used for testng is named poop2
- Telling it to shut down...
mosquitto_pub -h LXC-Mosquitto -t turd -m '{"Target":"poop2","Message": "It is time to DIE","Command":"DIE"}'
- Send a message to all logged-in users terminals
mosquitto_pub -h LXC-Mosquitto -t turd -m '{"Target":"poop2","Message": "This is a TURD","Command":"WALL"}'
- Just log a message (using random logger for testing)
mosquitto_pub -h LXC-Mosquitto -t turd -m '{"Target":"poop2","Message": "This is another TURD","Command":"MSG"}'
- Send a message to a different machine
mosquitto_pub -h LXC-Mosquitto -t turd -m '{"Target":"poop1","Message": "This is a TURD too","Command":"DoIt"}'