MQTT Type

Mandatory Options

The MQTT type is used by setting the type accordingly:

[my mqtt check]
type = mqtt
mqtt = <type of mqtt check>
server = the mqtt server
topic = list, of, topics
repair = repair command

The mqtt type offers the following options:

Option	Explanation
mqtt	the type of check that is used. Currently only timeout is implemented (mandatory)
topic	the topics that the configuration listens to, separated by a comma ',' (mandatory)
server	the name or IP address of the MQTT server (mandatory)
port	the port on the server on which the MQTT service runs (optional, default is 1883)
user	if a user is needed for the connection to the MQTT service you can set it here. Prerequisite for using a password. A user in the credentials overwrites this setting (optional)
password	if a password is needed for the connection to the MQTT service you can set it here. Important: If a password is needed then a user has to be set as well. A password in the credentials overwrites this setting (optional)
credentials	A file name referencing a file that contains a user and optionally a password in two different lines (a semicolon ';' marks a comment until the end of the line). Entries in the credentials file overwrite the options 'user' and 'password' (optional)
repair	This command is executed when the check was unsuccessful for longer than the set timeout
timeout	The timeout defines the maximum allowed time between successful checks. If this is exceeded, then a repair action or a fallback action is executed

Typically with MQTT you will use both a sleep time and a timeout far longer than for other configurations, since most IOT devices send messages only at longer intervals.

Using a credentials file is a good idea that allows you to keep your sensitive authentication data from the config file. Please remember to change the access rights of the file(s) so that only the user pi can read them. This can be done using the following command (assuming the file is named 'credentials.txt'):

> chmod go-rwx credentials.txt 

Example

Configuration

mqtt]
type = mqtt
mqtt = timeout
server = my_mqtt_server
; port = 1883
topic = first_floor/living_room/sensor/tele/STATE, first_floor/living_room/sensor/tele/LWT
repair = sudo systemctl restart networking
fallback = ls -l
;credentials = credentials.txt
;user = user
;password = passwd
sleep time = 60
timeout = 120

Credentials

; The following two lines contain the user and password
; information.
the_user_name
the_secret_password

Options overwriting defaults

The following options overwrite default values from the [general] section, if need be:

Option	Explanation
fallback	This is the fallback action that is executed if repairing was unsuccessful
sleep time	The daemon sleeps between checks of the current configuration for this time in seconds.