Subscribe to MQTT topics (with wildcards) and notifiy pluggable services
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To warn, alert, or notify.

Definition by Google

This program subscribes to any number of MQTT topics (which may include wildcards) and publishes received payloads to one or more notification services, including support for notifying more than one distinct service for the same message.

definition by Google

Notifications are transmitted to the appropriate service via plugins. We provide plugins for the list of services below, and you can easily add your own.

I've written an introductory post, explaining what mqttwarn can be used for. For example, you may wish to notify via e-mail and to Pushover of an alarm published as text to the MQTT topic home/monitoring/+.

Getting started


You'll need at least the following components:

  • Python 2.x (tested with 2.6 and 2.7)
  • An MQTT broker (e.g. Mosquitto)
  • The Paho Python module: pip install paho-mqtt


  1. Clone this repository into a fresh directory.
  2. Copy mqttwarn.ini.sample to mqttwarn.ini and edit to your taste
  3. Install the prerequisite Python modules for the services you want to use
  4. Launch

I recommend you use Supervisor for running this.

Alternatively, a systemd-based installation using a Python virtualenv might be handy, see systemd unit configuration file for mqttwarn for step-by-step instructions about doing this.


I recommend you start off with the following simple configuration which will log messages received on the MQTT topic test/+ to a file. Create the following configuration file:

hostname  = 'localhost'
port      = 1883

; name the service providers you will be using.
launch	 = file, log

append_newline = True
targets = {
    'mylog'     : ['/tmp/mqtt.log']

targets = {
    'info'   : [ 'info' ]

targets = file:mylog, log:info

Note: the closing brace } of the targets dict must be indented; this is an artifact of ConfigParser.

Launch and keep an eye on its log file (mqttwarn.log by default). Publish two messages to the subscribed topic, using

mosquitto_pub -t test/1 -m "Hello"
mosquitto_pub -t test/name -m '{ "name" : "Jane" }'

and our output file /tmp/mqtt.log should contain the payload of both messages:

{ "name" : "Jane" }

Both payloads where copied verbatim to the target.

Stop mqttwarn, and add the following line to the [test/+] section:

format  = -->{name}<--

What we are configuring mqttwarn to do here, is to try and decode the incoming JSON payload and format the output in such a way as that the JSON name element is copied to the output (surrounded with a bit of sugar to illustrate the fact that we can output whatever text we want).

If you repeat the publish of the second message, you should see the following in your output file /tmp/mqtt.log:


The [defaults] section

Most of the options in the configuration file have sensible defaults, and/or ought to be self-explanatory:

hostname     = 'localhost'         ; default
port         = 1883
username     = None
password     = None
clientid     = 'mqttwarn'
lwt          = 'clients/mqttwarn'  ; lwt payload is '0' or '1'
skipretained = True
cleansession = False

; logging
logformat = '%(asctime)-15s %(levelname)-5s [%(module)s] %(message)s'
logfile   = 'mqttwarn.log'

loglevel     = DEBUG

; path to file containing self-defined functions for formatmap, alldata, and datamap
functions = ''

; name the service providers you will be using.
launch   = file, log, osxnotify, mysql, smtp

; the directory to which we should cd after startup (default: ".")
; the cd is performed before loading service plugins, so it should
; contain a `services/' directory with the required service plugins.
directory = /tmp/

; optional: TLS parameters. (Don't forget to set the port number for
; TLS (probably 8883).
; You will need to set at least `ca_certs' if you want TLS support
; ca_certs: path to the Certificate Authority certificate file (concatenated
;           PEM file)
; tls_version: currently either 'tlsv1' or 'sslv3'
; tls_insecure: True or False (False is default): Do or do not verify
;               broker's certificate CN
; certfile: path to PEM encode client certificate file
; keyfile: path to PEM encode client private key file
ca_certs = '/path/to/ca-certs.pem'
certfile = '/path/to/client.crt'
keyfile = '/path/to/client.key'
tls_version = 'tlsv1'
tls_insecure = False

The functions option specifies the path to a Python file containing functions you use in formatting or filtering data (see below). The .py extension to the path name you configure here must be specified.


In the launch option you specify which services (of those available in the services/ directory of mqttwarn or using the module option, see the following paragraphs) you want to be able to use in target definitions.

The [config:xxx] sections

Sections called [config:xxx] configure settings for a service xxx. Each of these sections has a mandatory option called targets, which is a dictionary of target names, each pointing to an array of "addresses". Address formats depend on the particular service.

A service section may have an option called module, which refers to the name of the actual service module to use. A service called filetruncate - and referenced as such in the launch option - may have module = file, in which case the service works like a regular file service, with its own distinct set of service options. It is thus possible to have several different service configurations for the same underlying service, with different configurations, e.g. one for files that should have notifications appended, and one for files that should get truncated before writes.

As an example for module consider this INI file in which we want two services of type log. We actually launch an xxxlog (which doesn't physically exist), but due to the module=log setting in its configuration it is instantiated:

hostname  = 'localhost'  ; default
port      = 1883

launch	 = log, xxxlog

targets = {
    'debug'  : [ 'debug' ],

# Note how the xxxlog is instantiated from log and both must be launched
module = log
targets = {
    'debug'  : [ 'debug' ],

targets = log:debug, xxxlog:debug

The [failover] section

There is a special section (optional) for defining a target (or targets) for internal error conditions. Currently there is only one error handled by this logic, broker disconnection.

This allows you to setup a target for receiving errors generated within mqttwarn. The message is handled like any other with an error code passed as the topic and the error details as the message. You can use formatting and transformations as well as filters, just like any other topic.

Below is an example which will log any failover events to an error log, and display them on all XBMC targets:

targets  = log:error, xbmc
title    = mqttwarn

The [__topic__] sections

All sections not called [defaults] or [config:xxx] are treated as MQTT topics to subscribe to. mqttwarn handles each message received on this subscription by handing it off to one or more service targets.

The section name is the topic name (can be overridden using the topic option). Consider the following example:

targets = log:info, file:f01, mysql:nagios

targets = mysql:m1, log:info

MQTT messages received at icinga/+/+ will be directed to the three specified targets, whereas messages received at my/special will be stored in a mysql target and will be logged at level "INFO".

If more then one section is matching the topic then message will be handled to targets in all matching sections.

Targets can be also defined as a dictionary containing the pairs of topic and targets. In that case message matching the section can be dispatched in more flexible ways to selected targets. Consider the following example:

targets = {
    '/#': 'file:0',
    '/test/#': 'file:1',
    '/test/out/#': 'file:2',
    '/test/out/+': 'file:3',
    '/test/out/+/+': 'file:4',
    '/test/out/+/state': 'file:5',
    '/test/out/FL_power_consumption/state': [ 'file:6', 'file:7' ],
    '/test/out/BR_ambient_power_sensor/state': 'file:8',

With the message dispatching configuration the message is dispatched to the targets matching the most specific topic. If the message is received at /test/out/FL_power_consumption/state it will be directed to file:6 and file:7 targets only. Message received at /test/out/AR_lamp/state will be directed to file:5, but received at /test/out/AR_lamp/command will go to file:4. The dispatcher mechanism is always trying to find the most specific match. It allows to define the wide topic with default targets while some more specific topic can be handled differently. It gives additional flexibility in a message routing.

Each of these sections has a number of optional (O) or mandatory (M) options:

Option M/O Description
targets M service targets for this SUB
topic O topic to subscribe to (overrides section name)
filter O function name to suppress this msg
datamap O function name parse topic name to dict
alldata O function to merge topic, and payload with more
format O function or string format for output
priority O used by certain targets (see below). May be func()
title O used by certain targets (see below). May be func()
image O used by certain targets (see below). May be func()
template O use Jinja2 template instead of format
qos O MQTT QoS for subscription (dflt: 0)

Supported Notification Services

mqttwarn supports a number of services (listed alphabetically below):

Configuration of service plugins

Service plugins are configured in the main mqttwarn.ini file. Each service has a mandatory section named [config:xxx], where xxx is the name of the service. This section may have some settings which are required for a particular service, and all services have an rarely used option called module (see The config:xxx sections) and one mandatory option called targets. This defines individual "service points" for a particular service, e.g. different paths for the file service, distinct database tables for mysql, etc.

We term the array for each target an "address list" for the particular service. These may be path names (in the case of the file service), topic names (for outgoing mqtt publishes), hostname/port number combinations for xbmc, etc.


The amqp service basically implements an MQTT to AMQP gateway which is a little bit overkill as, say, RabbitMQ already has a pretty versatile MQTT plugin. The that as it may, the configuration is as follows:

uri     =  'amqp://user:password@localhost:5672/'
    'test01'     : [ 'name_of_exchange',    'routing_key' ],

The exchange specified in the target configuration must exist prior to using this target.

Requires: Puka (pip install puka)


The apns service interacts with the Apple Push Notification Service (APNS) and is a bit special (and one of mqttwarn's more complex services) in as much as it requires an X.509 certificate and a key which are typically available to developers only.

The following discussion assumes one of these payloads published via MQTT:

{"alert": "Vehicle moved" }
{"alert": "Vehicle moved", "custom" : { "tid": "C2" }}

In both cases, the message which will be displayed in the notification of the iOS device is "Vehicle moved". The second example depends on the app which receives the notification. This custom data is per/app. This example app uses the custom data to show a button:

APNS notification

This is the configuration we'll discuss.

hostname  = 'localhost'
port      = 1883
functions = 'myfuncs'

launch	 = apns

targets = {
                 # path to cert in PEM format   # key in PEM format
    'prod'     : ['/path/to/prod.crt',          '/path/to/prod.key'],

targets = apns
alldata = apnsdata()
format  = {alert}

Certificate and Key files are in PEM format, and the key file must not be password-protected. (The PKCS#12 file you get as a developer can be extracted thusly:

openssl pkcs12 -in apns-CTRL.p12 -nocerts -nodes | openssl rsa > prod.key
openssl pkcs12 -in apns-CTRL.p12 -clcerts -nokeys  > xxxx

then copy/paste from xxxx the sandbox or production certificate into prod.crt.)

The myfuncs function apnsdata() extracts the last part of the topic into apns_token, the hex token for the target device, which is required within the apns service.

def apnsdata(topic, data, srv=None):
    return dict(apns_token = topic.split('/')[-1])

A publish to topic test/token/380757b117f15a46dff2bd0be1d57929c34124dacb28d346dedb14d3464325e5 would thus emit the APNS notification to the specified device.

Requires PyAPNs


The autoremote service forwards messages from desired topics to autoremote clients.

targets = {
	'conv2' : [ 'ApiKey', 'Password', 'Target', 'Group', 'TTL' ]

targets = autoremote:conv2

Any messages published to autoremote/user would be sent the autoremote client designated to the ApiKey provided. The "sender" variable of autoremote is equal to the topic address.


The carbon service sends a metric to a Carbon-enabled server over TCP.

targets = {
        'c1' : [ '', 2003 ],

targets = carbon:c1

In this configuration, all messages published to c/# would be forwarded to the Carbon server at the specified IP address and TCP port number.

The topic name is translated into a Carbon metric name by replacing slashes by periods. A timestamp is appended to the message automatically.

For example, publishing this:

mosquitto_pub -t c/temp/arduino -m 12

would result in the value 12 being used as the value for the Carbon metric c.temp.arduino. The published payload may contain up to three white-space-separated parts.

  1. The carbon metric name, dot-separated (e.g. room.temperature) If this is omitted, the MQTT topic name will be used as described above.
  2. The integer value for the metric
  3. An integer timestamp (UNIX epoch time) which defaults to "now".

In other words, the following payloads are valid:

15					just the value (metric name will be MQTT topic) 15				metric name and value 15 1405014635		metric name, value, and timestamp


The celery service sends messages to celery which celery workers can consume.

broker_url = 'redis://localhost:6379/5'
app_name = 'celery'
celery_serializer = 'json'
targets = {
   'hello': [
        'task': 'myapp.hello',
        'message_format': 'json'

targets = celery:hello

Broker URL can be any broker supported by celery. Celery serializer is usually json or pickle. Json is recommended for security. Targets are selected by task name. Message_format can be either "json" or "text". If it is json, the message will be sent as a json payload rather than a string. In this configuration, all messages that match hello/ will be sent to the celery task "myapp.hello". The first argument of the celery task will be the message from mqtt.


The dbus service send a message over the dbus to the user's desktop (only tested with Gnome3).

targets = {
    'warn' : [ 'Warning' ],
    'note' : [ 'Note' ]


  • Python dbus bindings


The dnsupdate service updates an authoritative DNS server via RFC 2136 DNS Updates. Consider the following configuration:

dns_nameserver = ''
dns_keyname= 'mqttwarn-auth'
dns_keyblob= 'kQNwTJ ... evi2DqP5UA=='
targets = {
   #target             DNS-Zone      DNS domain              TTL,  type
   'temp'         :  [ 'foo.aa.',     '', 300, 'TXT'   ],
   'addr'         :  [ 'foo.aa.',     '',         60,  'A'   ],

targets = log:info, dnsupdate:temp
format = Current temperature: {payload}C

targets = log:info, dnsupdate:addr
format = {payload}

dns_nameserver is the address of the authoritative server the update should be sent to via a TCP update. dns_keyname and dns_keyblob are the TSIG key names and base64-representation of the key respectively. These can be created with either of:

ldns-keygen  -a hmac-sha256 -b 256 keyname
dnssec-keygen -n HOST -a HMAC-SHA256 -b 256 keyname

where keyname is the name then added to dns_keyname (in this example: mqttwarn-auth).

Supposing a BIND DNS server configured to allow updates, you would then configure it as follows:

key "mqttwarn-auth" {
  algorithm hmac-sha256;
  secret "kQNwTJ ... evi2DqP5UA==";

zone "foo.aa" in {
   type master;
   file "keytest/foo.aa";
   update-policy {
      grant mqttwarn-auth. zonesub ANY;

For the test/temp topic, a pub and the resulting DNS query:

$ mosquitto_pub -t test/temp -m 42'
$ dig @ +noall +answer txt 300 IN  TXT "Current temperature: 42C"

The test/a topic expects an address:

$ mosquitto_pub -t test/a -m
$ dig @ +short

Ensure you watch both mqttwarn's logfile as well as the log of your authoritative name server which will show you what's going on:

client mqttwarn-auth: view internal: updating zone 'foo.aa/IN': adding an RR at '' A



The emoncms service sends a numerical payload to an EmonCMS instance. EmonCMS is a powerful open-source web-app for processing, logging and visualising energy, temperature and other environmental data.

The web-app can run locally or you can upload your readings to their server for viewing and monitoring via your own login (note this is likely to become a paid service in the medium term). See for details on installing and configuring your own instance.

By specifying the node id and input name in the mqttwarn target (see the ini example below) you can split different feeds into different nodes, and give each one a human readable name to identify them in EmonCMS.

url     = <url of emoncms server e.g. http://localhost/emoncms or>
apikey  = <apikey generated by the emoncms server>
timeout = 5
targets = {
    'usage'  : [ 1, 'usage' ],  # [ <nodeid>, <name> ]
    'solar'  : [ 1, 'solar' ]


The execute target launches the specified program and its arguments. It is similar to pipe but it doesn't open a pipe to the program. Example use cases are f.e. IoT buttons which publish a message when they are pushed and the execute an external program. It is also a light version of mqtt-launcher.

targets = {
             # argv0 .....
   'touch' : [ 'touch', '/tmp/executed' ]

To pass the published data (text) to the command, use [TEXT] which then gets replaced. This can also be configured with the text_replace parameter.

Note, that for each message targeted to the execute service, a new process is spawned (fork/exec), so it is quite "expensive".


Notification of one Facebook account requires an account. For now, this is only done for messaging from one account to another.

Upon configuring this service's targets, make sure the three (3) elements of the list are in the order specified!

targets = {
  'janejol'   :  [ 'vvvvvvvvvvvvvvvvvvvvvv',                              # username sending message
                   'wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww',          # username's password (sending message)
                   'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx'  # destination account (receiving message)



The file service can be used for logging incoming topics, archiving, etc. Each message is written to a path specified in the targets list. Note that files are opened for appending and then closed on each notification.

Supposing we wish to archive all incoming messages to the branch arch/# to a file /data/arch, we could configure the following:

append_newline = True
overwrite = False
targets = {
    'log-me'    : ['/data/arch']

If append_newline is True, a newline character is unconditionally appended to the string written to the file. If overwrite is True, the file is opened for truncation upon writing (i.e. the file will contain the last message only).


The freeswitch service will make a VOIP call to the number specified in your target and 'speak' the message using the TTS service you specify. Each target includes the gateway to use as well as the number/extension to call, so you can make internal calls direct to an extension, or call any external number using your external gateway.

In order to use this service you must enable the XML RPC API in Freeswitch - see instructions here.

You need to provide a TTS URL to perform the conversion of your message to an announcement. This can be an online service like VoiceRSS or the Google Translate API (see example below). Or it could be a local TTS service you are using.

host      = 'localhost'
port      = 8050
username  = 'freeswitch'
password  = '<xml_rpc_password>'
ttsurl    = ''
ttsparams = { 'tl': 'en', 'ie': 'UTF-8', 'client': 'mqttwarn', 'q': '{payload}' }
targets   = {
    'mobile'    : ['sofia/gateway/domain/', '0123456789']


  • Freeswitch
  • Internet connection for Google Translate API


The asterisk service will make a VOIP conference between the number and the extension (in defined context). Also it sends the message as variable to the extension, so you can 'speak' to it. Configuration is similar as with the freeswitch service, but in service uses Asterisk Manager Interface (AMI).

The plugin author strongly recommends you use AMI only in trusted networks.

host     = 'localhost'
port     = 5038
username = 'mqttwarn'
password = '<AMI password>'
extension = 2222
context = 'default'
targets  = {
    'user'    : ['SIP/avaya/', '0123456789']


  • Asterisk with configured AMI interface (manager.conf)
  • pyst2 - powerful Python abstraction of the various Asterisk APIs (pip install pyst2)


The gss service interacts directly with a Google Docs Spreadsheet. Each message can be written to a row in a selected worksheet.

Each target has two parameters:

  1. The spreadsheet key. This is directly obtainable from the URL of the open sheet.
  2. The worksheet id. By default the first sheets id is 'od6'
username    =
password    = yourpassword
targets     = {
               # spreadsheet_key                               # worksheet_id
    'test': [ 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx',  'od6']


mosquitto_pub -t nn/ohoh -m '{"username": "jan", "device":"phone", "lat": "-33.8746097", "lon": "18.6292892", "batt": "94"}'

turns into


Note: It is important that the top row into your blank spreadsheet has column headings that correspond the values that represent your dictionary keys. If these column headers are not available, you will most likely see an error like this:

gdata.service.RequestError: {'status': 400, 'body': 'We&#39;re sorry, a server error occurred. Please wait a bit and try reloading your spreadsheet.', 'reason': 'Bad Request'}



The gss2 service interacts directly with a Google Docs Spreadsheet. Each message can be written to a row in a selected worksheet.

Each target has two parameters:

  1. The spreadsheet URL. You can copy the URL from your browser that shows the spreadsheet.
  2. The worksheet name. Try "Sheet1".
client_secrets_filename = client_secrets.json
oauth2_code =
oauth2_storage_filename =
targets = {
    # spreadsheet_url                                          # worksheet_name
    'test': [ '', 'Sheet1']
    # This target would be addressed as 'gss2:test'.

Note: It is important that the top row into your blank spreadsheet has column headings that correspond the values that represent your dictionary keys. If these column headers are not available or different from the dictionary keys, the new rows will be empty.

Note: Google Spreadsheets initially consist of 100 or 1,000 empty rows. The new rows added by gss2 will be below, so you might want to delete those empty rows.

Other than gss, gss2 uses OAuth 2.0 authentication. It is a lot harder to get working - but it does actually work.

Here is an overview how the authentication with Google works:

  1. You obtain a client_secrets.json file from Google Developers Console.
  2. You reference that file in the client_secrets_filename field and restart mqttwarn.
  3. You grab an URL from the logs and visit that in your web browser.
  4. You copy the resulting code to mqttwarn.ini, field oauth2_code and restart mqttwarn.
  5. gss2 stores the eventual credentials in the file you specified in field oauth2_storage_filename.
  6. Everyone lives happily ever after. I hope you reach this point without severe technology burnout.
  7. Technically, you could remove the code from field oauth2_code, but it does not harm to leave it there.

Now to the details of this process: The contents of the file client_secrets_filename needs to be obtained by you as described in the Google Developers API Client Library for Python docs on OAuth 2.0 for an Installed Application. Unfortunately, Google prohibits developers to publish their credentials as part of open source software. So you need to get the credentials yourself.

To get them:

  1. Log in to the Google Developers website from here.
  2. Follow the instructions in section Creating application credentials from the OAuth 2.0 for Installed Applications chapter. You are looking for an OAuth client ID.
  3. In the Credentials screen of the API manager there is a download icon next to your new client ID. The downloaded file should be named something like client_secret_664...json.
  4. Store that file near e.g. mqttwarn.ini and ensure the setting client_secrets_filename has the valid path name of it.

Then you start with the gss2 service enabled and with the client_secrets_filename readable. Once an event is to be published, you will find an error in the logs with a URL that you need to visit with a web browser that is logged into your Google account. Google will offer you to accept access to Google Docs/Drive. Once you accept, you get to copy a code that you need to paste into field oauth2_code and restart mqttwarn.

The file defined in oauth2_storage_filename needs to be missing or writable and will be created or overwritten. Once OAuth credentials have been established (using the oauth2_code), they are persisted in there.



The hangbot service allows messages to be forwarded to a Google Hangouts account using hangoutsbot api plugin.

targets = {
		 #URL		 #PORT	 #ApiKey	#Conversation ID
   'conv1'   : ['ServerAddress', 'Port', 'xxxxxxxxxxx', 'xxxxxxxxxxxxxxxxxxxx']


The hipchat plugin posts messages to rooms of the service or self-hosted edition. The configuration of this service requires an API v2 token and RoomID (you can configure them on => Group Admin => Rooms => Tokens) only the Send Notification scope is required.


#server = ""  # Optional, default is
timeout = 10 # Default 60 seconds

targets = {
                     #token         #roomid  #color #notify
  'room-ops'    : [ "yyyyyyyyyyyyy", "000", "red", True ],
  'room-dev'    : [ "xxxxxxxxxxxxx", "111", "green", False ]

The available colors for the background of the message are: "yellow", "green", "red", "purple", "gray" or if you feel lucky "random"

The notify parameter (True or False) trigger a user notification (change the tab color, play a sound, notify mobile phones, etc).



The http service allows GET and POST requests to an HTTP service.

Each target has five parameters:

  1. The HTTP method (one of get or post)
  2. The URL, which is transformed if possible (transformation errors are ignored)
  3. None or a dict of parameters. Each individual parameter value is transformed.
  4. None or a list of username/password e.g. ( 'username', 'password')
  5. None or True to force the transformation of the third parameter to a json object and to send the HTTP header Content-Type with a value of application/json when using post
timeout = 60

targets = {
                #method     #URL               # query params or None                              # list auth # Json
  'get1'    : [ "get",  "", { 'q': '{name}', 'isod' : '{_dtiso}', 'xx': 'yy' }, ('username', 'password') ],
  'post1'    : [ "post", "", { 'q': '{name}', 'isod' : '{_dtiso}', 'xx': 'yy' }, None, True ]

If you want to use the mqtt message content directly in the query parameters use '{payload}'

Note that transforms in parameters must be quoted strings:

  • Wrong: 'q' : {name}
  • Correct: 'q' : '{name}'

As a special case, if the quoted parameter starts with an @ character (e.g. '@name', it will not be formatted via .format(); instead, name is taken directly from the transformation data.


This service is for the REST API in Icinga2. Icinga2 is an open source monitoring solution.

Using this service JSON payloads can be sent to your Icinga2 server to indicate host/service states or passive check updates.

By default the service will POST a process-check-result to your Icinga2 server with the following payload;

payload  = {
    'service'       : 'host-name!service-name',
    'check_source'  : 'check-source',
    'exit_status'   : priority,
    'plugin_output' : message

Where the host-name, service-name and check-source come from the service config (see below), the priority is the standard mqttwarn priority, either hard coded or derived via a function, and the message is the payload arriving on the MQTT topic.

NOTE: if service-name is None in the target config the payload will include 'host' : 'host-name' instead of the 'service' entry, and can be used for host checks.

However it is possible to create your own payload by adding a custom format function where you can specify a dict of key/value pairs and these will be used to update the payload sent to Icinga2.

For example we can add a custom function which returns;

def icinga2_format(data, srv):
    icinga2_payload = {
        'exit_status'  : 0,
        'plugin_output': "OK: my-service is publishing",
        'service'      : "!my-service",

    return json.dumps(icinga2_payload)

This allows you to manipulate the status, output and service name by parsing topic names and message payloads.

host     = 'https://icingahost'
port     = 5665
username = 'api-username'
password = 'api-password'
cacert   = '<path-to-ca-cert>'
targets  = {
                        # host-name   service-name  check-source
    'host-check '    : [ '',  None,         'mqttwarn' ],
    'service-check ' : [ '',  'passive',    'mqttwarn' ],

NOTE: cacert is optional but since icinga2 is typically installed with a self-signed certificate specifying the icinga2 ca-cert will stop a load of TLS certificate warnings when connecting to the REST API.


this service is for ifttt maker applet to send the message as a payload in value1. For example, to get notifications on your mobile devices.

targets = {
    'warnme'   : [ '<api key>', '<event webhook>' ]


This service is for Ionic. Ionic framework allows easy development of HTML5 hybrid mobile apps. This service can be used for pushing notifications to ionic hybrid apps (android, ios, ...). Please read following for more details on ionic: Ionic tutorial and Ionic push service

You will get Ionic appid and Ionic appsecret (private key) after registering with Ionic push service. And you will get device token(s) when app initiates push service interaction.

Using this service, plain texts can be sent to one or many ionic apps. And each app can in turn push to many devices. Following is the ini example:

targets = {
  'anyappalias' : [ '<ionic app id>', '<ionic app secret>', '<device token 1>', '<device token 2>', '<device token N>']



This service is for Microsoft Azure IoT Hub. The configuration requires a hostname for the IoT Hub, all other service configuration options are optional. Each target defines which device to impersonate when sending the message.

hostname = '<name>'
# protocol = 'AMQP'/'MQTT'/'HTTP' # Optional, default is AMQP
# message_timeout = 10000 # Optional, default is not to expire
# timeout = 10 # Optional, for HTTP transport only
# minimum_polling_time = 9 # Optional, for HTTP transport only
targets = {
               # device id   # device key
    'test' : [ 'pi',         'uN...6w=' ]

Note that the actual message delivery is done asynchronously, meaning that successful processing is no guarantee for actual delivery. In the case of an error occurring, an error message should eventually appear in the log.



This service provides a way for forwarding data to the time series database InfluxDB (v9+).

You will need to install an instance of InfluxDB (v9+) and create a new user. Then create a new database and give your user write permissions to that database.

You can then setup multiple targets, each of which is a different measurement in your InfluxDB database.

Each time a value is received for an InfluxDB target, the value is sent to the configured measurement with a topic tag matching the MQTT topic the data arrived on.

The topic name is normalised by replacing / with _. So a value arriving on sensor/kitchen/temperature would be published to InfluxDB with a tag of topic=sensor_kitchen_temperature.

This allows you to setup measurements with multiple time series streams, or have a separate measurement for each stream.

Following is an ini example, showing the various connection properties for the InfluxDB database, and some example target configs;

host      = 'influxdbhost'
port      = 8086
username  = 'username'
password  = 'password'
database  = 'mqttwarn'
targets = {
                          # measurement
    'humidity'         : [ 'humidity' ],
    'temperature'      : [ 'temperature' ]


This service is for Instapush, an app for both IOS and Android, which provides free instant notifications.

You should first create an application and respective event following the tutorial.

Afterward you will find your Application ID and Application Secret in the "Basic Info" of your application.

Each mqttwarn target corresponds to an event in your Instapush application.

The "trackers" in Instapush correspond to JSON values in the mqttwarn config:instapush section or from the message payload. You can define as many trackers as you wish.

Consider the following event created in Instapush:

Field Value
Event title alerts
Trackers object, action
Push Message {object} just {action}

To always send the same object and action tracker values, set them as constants in the event of the target:

appid = '12345abc123456'
appsecret = '1234567890abcd123456789abcdef123456789'
targets = {
             # event   # trackers
  'notify' : [ 'alerts', {"object":"door", "action":"opened/closed"}]


To send tracker values based on the message payload, leave out the tracker element of the target definition in the config:instapush section: If your target is a list with only 1 element, that element will be considered the "event" and the "trackers" will be taken from the mqtt payload, which must have all tracker fields present.


The irccat target fires a message off to a listening irccat which has a connection open on one or more IRC channels.

Each target has to be configured with the address, TCP port and channel name of the particular irccat it should target.

targets = {
             # address     port   channel
   'chan1': [ '', 12345, '#testchan1' ],
Topic option M/O Description
priority O Colour: 0=black, 1=green, 2=red

The priority field can be used to indicate a message colour.



The linuxnotify service is used to display notifications on a running desktop environment (only tested with Gnome3).

targets = {
    'warn' : [ 'Warning' ]



  • gobject-introspection Python bindings


The log service allows us to use the logging system in use by mqttwarn proper, i.e. messages directed at log will land in mqttwarn's log file.

targets = {
    'info'   : [ 'info' ],
    'warn'   : [ 'warn' ],
    'crit'   : [ 'crit' ],
    'error'  : [ 'error' ]


The mattermost service sends messages to a private Mattermost instance using incoming Webhooks.

Consider the following configuration:

  • hook_url is the URL of the incoming Webhook
  • channel is the name of the channel
  • username (can be None) specifies the user name as which mqttwarn will post if the Mattermost administrator has allowed override
  • icon_url is the URL to an icon (can be None, and if not must be resolvable to Mattermost)
targets = {
                 # hook_url, 	channel, 	username, 	icon_url
    'jpt'	: [ 'http://localhost:8065/hooks/s9x9x8xywjgw9x9x8xyqiujcyo',
			'' ],
    'vehicles'	: [ '',
			'' ],

targets = mattermost:jpt
format = I'll have a {fruit} if it costs {price}

title = Owntracks position
targets = mattermost:vehicles

This will, with appropriate JSON paylods, produce the following posts in Mattermost.


Note how this service attempts to format incoming JSON as a Markdown table.


The mqtt service fires off a publish on a topic, creating a new connection to the configured broker for each message.

Consider the following configuration snippets:

hostname =  'localhost'
port =  1883
qos =  0
retain =  False
username =  "jane"
password =  "secret"
targets = {
  'o1'    : [ 'out/food' ],
  'o2'    : [ 'out/fruit/{fruit}' ],
  'm2'	  : [ 'sometopic', 'specialmq.ini' ],

targets = mqtt:o1, mqtt:o2
format =  u'Since when does a {fruit} cost {price}?'

The topicmap specifies we should subscribe to in/a1 and republish to two MQTT targets. The second target (mqtt:o2) has a topic branch with a variable in it which is to be interpolated ({fruit}).

These are the results for appropriate publishes:

$ mosquitto_pub -t 'in/a1' -m '{"fruit":"pineapple", "price": 131, "tst" : "1391779336"}'

in/a1 {"fruit":"pineapple", "price": 131, "tst" : "1391779336"}
out/food Since when does a pineapple cost 131?
out/fruit/pineapple Since when does a pineapple cost 131?

$ mosquitto_pub -t 'in/a1' -m 'temperature: 12'

in/a1 temperature: 12
out/food temperature: 12
out/fruit/{fruit} temperature: 12

In the first case, the JSON payload was decoded and the fruit variable could be interpolated into the topic name of the outgoing publish, whereas the latter shows the outgoing topic branch without interpolated values, because they simply didn't exist in the original incoming payload.

The optional second value in the topic map (specialmq.ini in the example above) specifies the name of an INI-type file with parameters which override the basic configuration of this service. Assume most of your MQTT targets go to localhost, but you want one target to be configured to address a distinct MQTT broker. Create an INI file with any name you desire and specify that as the optional second parameter:

port= 1884
client_id = blub01
qos = 1
retain = False

username = jjolie
password = seecret

ca_certs = foobar.crt
;certfile = xxx.crt
;keyfile = xxx.key
tls_version = tlsv1
;ciphers = xxxxx xx

This shows the currently full configuration possible. Global values from the mqtt service override those not specified here. Also, if you don't need authentication (auth) or (tls) you may omit those sections. (The defaults section must exist.)


This service publishes a message to the broker mqttwarn is connected to. (To publish a message to a different broker, see mqtt.)

Each target requires a topic name, the desired qos and a retain flag.

targets = {
                # topic            qos     retain
    'mout1'   : [ 'mout/1',         0,     False ],
    'special' : [ 'some/{device}',  0,     False ],

If the outgoing topic name contains transformation strings (e.g. out/some/{temp}) values are interpolated accordingly. Should this not be possible, e.g. because a string isn't available in the data, the message is not published.


The MySQL plugin is one of the most complicated to set up. It requires the following configuration:

host  =  'localhost'
port  =  3306
user  =  'jane'
pass  =  'secret'
dbname  =  'test'
targets = {
          # tablename  #fallbackcolumn ('NOP' to disable)
 'm2'   : [ 'names',   'full'            ]

Suppose we create the following table for the target specified above:

CREATE TABLE names (id INTEGER, name VARCHAR(25));

and publish this JSON payload:

mosquitto_pub -t my/2 -m '{ "name" : "Jane Jolie", "id" : 90, "number" : 17 }'

This will result in the two columns id and name being populated:

| id   | name       |
|   90 | Jane Jolie |

The target contains a so-called fallback column into which mqttwarn adds the "rest of" the payload for all columns not targeted with JSON data unless that is explicitly configured as NOP in the service in which case extra data is discarded. I'll now add our fallback column to the schema:


Publishing the same payload again, will insert this row into the table:

| id   | name       | full                                                |
|   90 | Jane Jolie | NULL                                                |
|   90 | Jane Jolie | { "name" : "Jane Jolie", "id" : 90, "number" : 17 } |

As you can imagine, if we add a number column to the table, it too will be correctly populated with the value 17.

The payload of messages which do not contain valid JSON will be coped verbatim to the fallback column:

| id   | name | full        | number |
| NULL | NULL | I love MQTT |   NULL |

You can add columns with the names of the built-in transformation types (e.g. _dthhmmss, see below) to have those values stored automatically.


Similar to the MySQL plugin but tables and columns are created dynamically as needed. The name of the table is composed from the topic, replacing the dash separator with underscores. As an example, the topic device/laptop/tracksresults in the creation of a table named device_laptop_tracks.

The message will be processed and each JSON field will be stored in a different column. The columns of each table (and the table itself) are created when the first message is published to the topic. The configuration allows to specify the fields to ignore. These will not be stored in the database.

As an example, by publishing this JSON payload:

mosquitto_pub -t my/2 -m '{ "name" : "Jane Jolie", "id" : 90, "number" : 17 }'

A table named my_2 will be created on the fly with the following structure and content (the table name is derived from the MQTT topic, but slashes are replaced by underscores):

| id   | name       | number | payload                                               |
|   90 | Jane Jolie | 17     | '{ "name" : "Jane Jolie", "id" : 90, "number" : 17 }' |

Please note that by default, the information is always stored in a duplicated form: each field, and all fields together as sent. If you can use the field ignore capability (see below) to disable this behaviour. Actually, lots of other fields (created by mqttwarn) may be present. Adjust your configuration as required.

An index table, containing a timestamp and the name of the topic, will keep track of the latest update to the remaining tables. The name of the index table can be specified in the configuration, and must be created manually. The following statements create an index table named ```index_table_name``:

CREATE TABLE `index_table_name` (
  `topic` text NOT NULL,
  PRIMARY KEY `topic` (`topic`(128))

This module requires the following configuration to be present in the configuration file:

host  =  'localhost'
port  =  3306
user  =  'dbusername'
pass  =  'dbpassword'
dbname  =  'database'
index   =  'index_table_name'

targets = {
        # target to use: [ list of fields to ignore and not store ]
        'target_name' : ['field1', 'field2','field3' ]



At this point, if the payload format changes, the tables are not modified and data may fail to be stored. Also, there is no fallback table or column like the case of the MySQL plugin.


This service was originally designed to transform and store SonOff telemetry messages into a MySQL database, where database doen't need to have columns with same name as values in the MQTT messages.

My new service (called mysql_remap) inserts new record into MySQL. This is a generic service, however, I designed it to colelct telemetry data from my SonOff POW devices. This service can add static values (like the source/meaning of the data; e.g. 'bojler_enabled') and can remap keys (e.g. current power consumption data comes as 'current' but stored in DB as 'value').

Example configuration:

In the below configuration 'test' is the name of the table, 'Time' is a key comes from the MQTT message what will be renamed to 'timestamp' when service insert the data intothe table. If a message key isn't named here it won't be inserted into the database even it is in the message.

'description' is a column name in the database table and 'heater_power' is a constant to make filtering possible later on by SQL querys. You can add zero or more from these.

hostname  = 'localhost'
port      = 1883
loglevel  = DEBUG

launch   = mysql_remap

#functions = ''

host  =  'localhost'
port  =  3306
user  =  'root'
pass  =  '123'
dbname  =  'test'
targets = {
         't1'   : [ 'test',
                              'Time': 'timestamp',
                              'Power': 'value'
                              'description' : 'heater_power'

targets = mysql_remap:t1
#alldata = powerBinFunc()

You can also do some further transformation on the message before insert it into the databse using by the two uncommented lines above and the below function (need to copy it into

This below example convert reveived data and time information itno unix timestam format and replace "ON" and "OFF" values to 1 and 0 numbers.

# -*- coding: utf-8 -*-
import time
import copy
import ast
from datetime import datetime

def powerBinFunc(topic, data, srv=None):
    # parse json payload (the message)
    payload = ast.literal_eval(data["payload"])

    # Override default time format
    dt = datetime.strptime(payload["Time"], '%Y-%m-%dT%H:%M:%S')
    ts = time.mktime(dt.timetuple())
    ret = dict( payload = dict( Time = ts ))

    # Check power state key
    if "POWER" in payload:
        if payload["POWER"] == "ON":
            ret["POWER_BIN"] = 1
            ret["POWER_BIN"] = 0

    return ret

# vim: tabstop=4 expandtab

Example MQTT message:

17:08:45 MQT: tele/bojler/SENSOR = {"Time":"2018-04-15T17:08:45","ENERGY":{"Total":320.144,"Yesterday":5.105,"Today":1.881,"Period":0,"Power":17.15,"Factor":0.07,"Voltage":234,"Current":0.128}}

Example MySQL records:

| timestamp  | value     | description    |
| 1523804925 |  17.15000 | heater_power   |


This service allows for on-screen notification pop-ups on MythTV instances. Each target requires the address and port of the MythTV backend instance (<hostname>:<port>), and a broadcast address.

timeout = 10  # duration of notification
targets = {
                          # host:port,            broadcast address
    'all'               :  [ '', ''],
    'frontend_bedroom'  :  [ '', '' ]
Topic option M/O Description
title O notification title (dflt: mqttwarn)
image O notification image URL


The nma service uses NMA (Notify My Android) to delivery notifications from mqttwarn to your Android device.

targets = {
                 # api key                                            app         event
  'myapp'    : [ 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx', "Nagios",  "Phone call" ]
Topic option M/O Description
priority O priority. (dflt: 0)




The nntp target is used to post articles to an NNTP news server on a particular newsgroup.

server  = t1.prox
port    = 119
; username = ""
; password = "secret"
targets = {
    #              from_hdr                       newsgroup
    'aa'     : [ 'Me and I <>',    'jp.aa' ],

Each target's configuration includes the value given to the From: header as well as a single newsgroup to which the article is posted.

Topic option M/O Description
title O The post's subject (dflt: mqttwarn)


mosquitto_pub -t nn/ohoh -m '{"name":"Jane Jolie","number":47, "id":91}'

turns into

Path: t1.prox!t1.prox!not-for-mail
Content-Type: text/plain; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
From: Me and I <>
Subject: Hi there Jane Jolie
Newsgroups: jp.aa
Date: Wed, 26 Mar 2014 22:41:25 -0000
User-Agent: mqttwarn
Lines: 1
Message-ID: <5332caf6$0$20197$41d98655@t1.prox>

Jane Jolie: 47 => 13:41


The nsca target is used to submit passive Nagios/Icinga checks to an NSCA daemon.

Consider the following Icinga service description which configures a passive service:

define service{
        use                    generic-service
        host_name              localhost
        service_description    Current temp via MQTT
        active_checks_enabled  0
        passive_checks_enabled 1
        check_freshness         0
        check_command          check_dummy!1

with the following target definition in

nsca_host = ''
targets = {
   #              Nagios host_name,     Nagios service_description,
   'temp'    :  [ 'localhost',          'Current temp via MQTT' ],

targets = nsca:temp
; OK = 0, WARNING = 1, CRITICAL = 2, UNKNOWN = 3
priority = check_temperature()
format = Current temperature: {temp}C

Also, consider the following PUB via MQTT:

mosquitto_pub -t arduino/temp -m '{"temp": 20}'

Using a transformation function for priority to decide on the status to be sent to Nagios/Icinga, we obtain the following:


Topic option M/O Description
priority O Nagios/Icinga status. (dflt: 0)

The transformation function I've defined as follows:

def check_temperature(data):
    '''Calculate Nagios/Icinga warning status'''
    OK = 0
    WARNING = 1
    CRITICAL = 2
    UNKNOWN = 3
    if type(data) == dict:
        if 'temp' in data:
            temp = int(data['temp'])
            if temp < 20:
                return OK
            if temp < 25:
                return WARNING
            return CRITICAL

    return UNKNOWN


  • pynsca, but you don't have to install that; it suffices if you drop alongside (i.e. in the same directory)


  • Requires Mac ;-) and pync which uses the binary terminal-notifier created by Eloy Durán. Note: upon first launch, pync will download and extract into a directory vendor/.
Topic option M/O Description
title O application title (dflt: topic name)

If url is defined in, its value is passed to the notification, so that the URL is opened in the system's default Web browser when the notification is clicked. (The notification itself has no visual indication that such is possible.)



The osxsay target alerts you on your Mac (warning: requires a Mac :-) with a spoken voice. It pipes the message (which is hopefully text only) to the say(1) utility. You can configure any number of different targets, each with a different voice (See say -v ? for a list of allowed voice names.)

targets = {
                 # voice (see say(1) or `say -v ?`)
    'victoria' : [ 'Victoria' ],
    'alex'     : [ 'Alex' ],
targets = osxsay:victoria
targets = osxsay:alex
  • Note: this requires your speakers be enabled and can be a pain for co-workers or family members, and we can't show you a screen shot...


The pastebinpub service is publishing messages to Pastebin.

Note: Be careful what you post on this target, it could be public. If you are not a paying customer of Pastebin you are limited to 25 unlisted and 10 private pastes.

targets = {
    'warn' : [ 'api_dev_key',  # API dev key
               'username',  # Username
               'password',  # Password
                1,  # Privacy level
               '1H'  # Expire



  • An account at Pastebin
  • Python bindings for the Pastebin API You don't have to install this -- simply copy to the mqttwarn directory. curl -O


The pipe target launches the specified program and its arguments and pipes the (possibly formatted) message to the program's stdin. If the message doesn't have a trailing newline (\n), mqttwarn appends one.

targets = {
             # argv0 .....
   'wc'    : [ 'wc',   '-l' ]

Note, that for each message targeted to the pipe service, a new process is spawned (fork/exec), so it is quite "expensive".


The postgres plugin behaves virtually identically to the MySQL plugin above. It is configured in the same way:

host  =  'localhost'
port  =  5432
user  =  'jane'
pass  =  'secret'
dbname  =  'test'
targets = {
          # tablename  # fallbackcolumn  # schema
 'pg'   : [ 'names',   'message',	 'schema' ]

Suppose we create the following table for the target specified above:


and publish this JSON payload:

mosquitto_pub -t pg/1 -m '{ "name" : "Jane Jolie", "id" : 90, "number" : 17 }'

This will result in the two columns id and name being populated:

| id   | name       |
|   90 | Jane Jolie |

Exactly as in the MySQL plugin, a fallback column can be defined into which mqttwarn adds the "rest of" the payload for all columns not targeted with JSON data. Lets now add our fallback column to the schema:

ALTER TABLE names ADD message TEXT;

Publishing the same payload again, will insert this row into the table:

| id   | name       | message                                             |
|   90 | Jane Jolie | NULL                                                |
|   90 | Jane Jolie | { "name" : "Jane Jolie", "id" : 90, "number" : 17 } |

As you can imagine, if we add a number column to the table, it too will be correctly populated with the value 17.

The payload of messages which do not contain valid JSON will be coped verbatim to the fallback column:

| id   | name | message     | number |
| NULL | NULL | I love MQTT |   NULL |

You can add columns with the names of the built-in transformation types (e.g. _dthhmmss, see below) to have those values stored automatically.


This service is for Prowl. Each target requires an application key and an application name.

targets = {
                    # application key                           # app name
    'pjpm'    :  [ 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx', 'SuperAPP' ]
Topic option M/O Description
title O application title (dflt: mqttwarn)
priority O priority. (dflt: 0)




This service is for pushalot, which is a notifier app for Windows Phone and Windows8.

It requires an Authorization token, which you can generate after creating an account at We can then use that to configure the target definition:

targets = {
                   # Authorization token
    'info'     : ['xxxxxxxxxxxxxxxxxxxxxxx'],
    'warn'     : ['xxxxxxxxxxxxxxxxxxxxxxx']
Topic option M/O Description
title O application title (dflt: mqttwarn)



  • a pushalot account with Authorization token


This service is for PushBullet, an app for Android along with an extension for Chrome, which allows notes, links, pictures, addresses and files to be sent between devices.

You can get your API key from here after signing up for a PushBullet account. You will also need the device ID to push the notifications to. To obtain this you need to follow the instructions at pyPushBullet and run ./ YOUR_API_KEY_HERE getdevices.

targets = {
                   # API KEY                  device ID,    recipient_type
    'warnme'   : [ 'xxxxxxxxxxxxxxxxxxxxxxx', 'yyyyyy',     'tttt' ]

where the optional recipient_type could be one of device_iden (default), email, channel or client.

Topic option M/O Description
title O application title (dflt: mqttwarn)



  • a Pushbullet account with API key
  • pyPushBullet. You don't have to install this -- simply copy to the mqttwarn directory.


This service is for Pushover, an app for iOS and Android. In order to receive pushover notifications you need what is called a user key and one or more application keys which you configure in the targets definition:

callback = None
targets = {
    'nagios'     : ['userkey1', 'appkey1', 'sound1'],
    'alerts'     : ['userkey2', 'appkey2'],
    'tracking'   : ['userkey1', 'appkey2', 'sound3'],
    'extraphone' : ['userkey2', 'appkey3']

This defines four targets (nagios, alerts, etc.) which are directed to the configured user key and app key combinations. This in turn enables you to notify, say, one or more of your devices as well as one for your spouse. As you can see in the example, you can even specify an optional sound to be played for the individual users. For a list of available sounds see the Pushover API List.

NOTE: callback is an optional URL for pushover to ack messages.

Topic option M/O Description
title O application title (dflt: pushover dflt)
priority O priority. (dflt: pushover setting)

The pushover service will accept a payload with either a simple text message, or a json payload which contains a message and either an imageurl or imagebase64 encoded image.

The following payloads are valid;

Simple text message
    "message": "Message only, with no image"
    "message": "Message with base64 encoded image",
    "imagebase64": "<base64 encoded image>"
    "message": "Message with image downloaded from URL",
    "imageurl": "<image url>"

pushover on iOS



This service is for Pushsafer, an app for iOS, Android and Windows 10. In order to receive pushsafer notifications you need what is called a private or alias key:

targets = {
    'nagios'     : ['privatekey', 'Device ID', 'Icon', 'Sound', 'Vibration', 'URL', 'Url Title', 'Time2Live'],
    'tracking'   : ['aliaskey1'],
    'extraphone' : ['aliaskey2', '', '', '', '', '', '', '60'],
	'warnme'     : ['aliaskey3', '', '', '', '', '', '', '60']

This defines targets (nagios, alerts, etc.) which are directed to the configured private or alias key combinations. This in turn enables you to notify, say, one or more of your devices as well as one for your spouse. For a list of available icons, sounds and other params see the Pushsafer API.

Topic option M/O Description
title O application title (dflt: pushsafer dflt)

pushsafer on iOS



The redispub plugin publishes to a Redis channel.

host  =  'localhost'
port  =  6379
targets = {
    'r1'      : [ 'channel-1' ]



The rrdtool plugin updates a round robin database created by rrdtool with the message payload.

targets = {
    'living-temp'  : ['/tmp/living-temp.rrd',  '--template', 'temp'],
    'kitchen-temp' : ['/tmp/kitchen-temp.rrd', '--template', 'temp']

rrdpython's API expects strings and/or list of strings as parameters to the functions. Thus a list for a target simply contains the command line arguments for rrdtool update. The plugin will embed the message as final argument N:<message>, if the message is an integer number. Otherwise, it will break up the message into single words and append this list to the list supplied by the target. This leaves it to your descretion where to put arguments and even - with the right data mapping and extraction in place - allows for something like

targets = {
        'battsensor': [ ],
topic = datalog/sensors/batt/+
targets = log:info,rrdtool:battsensor
datamap = ...
format = /srv/rrd/sensors/{sensor_id}.rrd -t batt {ts}:{batt}

Requires the rrdtool bindings available with pip install rrdtool.


The serial plugin sends out received messages to the serial port. Message payload can be binary data, string or json.

append_newline = False
targets = {
    'serialport1'  : ['/dev/ttyUSB0',  '115200'],
    'some-device' : ['socket://', '9600']

First parameter in target config can be a portname or an url handler. Second parameter is the baudrate for the port. If append_newline is True, a newline character is unconditionally appended to the string written to the serialport.

Requires the pyserial bindings available with pip install pyserial.


The slack plugin posts messages to channels in or users of the service. The configuration of this service requires an API token obtaininable there.

token = 'xxxx-1234567890-1234567890-1234567890-1234a1'
targets = {
                #   [token,] #channel/@user, username, icon, [as_user]
   'jpmens'     : [ '@jpmens',   "Alerter",   ':door:'          ],
   'general'    : [ '#general',  "mqttwarn",  ':syringe:'       ],
   'test'       : [ '#test',     "BotUser",   ':unused:',  True ],
   'second-acc' : [ 'xxxx-9999999-9999999-99999999', '#general', "test", ':house:' ],

The service level token is optional, but if missing each target must have a token defined.

Each target defines the name of an existing channel (#channelname) or a user (@username) to be addressed, the name of the sending user as well as an emoji icon to use.

Optionally, a target can define the message to get posted as a user, per Slack Authorship documentation. Note that posting as a user in a channel is only possible, if the user has joined the channel.


This plugin requires Python slacker.


The sqlite plugin creates a table in the database file specified in the targets, and creates a schema with a single column called payload of type TEXT. mqttwarn commits messages routed to such a target immediately.

targets = {
                   #path        #tablename
  'demotable' : [ '/tmp/m.db',  'mqttwarn'  ]


The sqlite_json2cols plugin creates a table in the database file specified in the targets and creates a schema based on the JSON payload. It will create a column for each JSON entry and rudimentary try to determine its datatype on creation (Float or Char).

As an example, publishing this JSON payload:

mosquitto_pub -t test/hello -m '{ "name" : "Thor", "Father" : 'Odin', "Age" : 30 }'

A table as stated in the configuration will be created on the fly with the following structure and content:

| name | Father | Age  |
| Thor | Odin   | 30.0 |

No table is created if the table name already exists.

mqttwarn commits messages routed to such a target immediately.

targets = {
                   #path        #tablename
  'demotable' : [ '/tmp/m.db',  'mqttwarn'  ]


The sqlite_timestamp plugin works just like the 'sqlite' plugin, but it creates 3 columns: id, payload and timestamp. The id is the table index and the timestamp is the insertion date and time in seconds.

targets = {
                   #path        #tablename
  'demotable' : [ '/tmp/m.db',  'mqttwarn'  ]


The smtp service basically implements an MQTT to SMTP gateway which needs configuration.

server  =  'localhost:25'
sender  =  "MQTTwarn <jpm@localhost>"
username  =  None
password  =  None
starttls  =  False
# Optional send msg as html or only plain text
htmlmsg   =  False
targets = {
    'localj'     : [ 'jpm@localhost' ],
    'special'    : [ 'ben@gmail', '' ]

Targets may contain more than one recipient, in which case all specified recipients get the message.

Topic option M/O Description
title O e-mail subject. (dflt: mqttwarn notification)


The ssh service can run commands over ssh. If both user and password are defined in the config, they will be used to connect to the host. If both user and password are not defined in the config, the service will parse the user's ssh config file to see which key (IdentityFile) to use; it will also look for User and Port in this file.

If using a key, only the host is required.

The output is ignored for now.

Note: using this module lets you specify a username and a password which can be used to login to the target system. As such, your mqttwarn.ini configuration file should be well protected from prying eyes! (This applies generally, for other target specifications with credentials as well.)

host  = ''
port  = 22
user  = 'username'
pass  = 'password'
targets = {
		's01'    : [ 'command with one substitution %s' ],
		's02'    : [ 'command with two substitutions %s__%s' ]

format = {args}
targets = ssh:s01

format = {args}
targets = ssh:s02

Targets may contain ONE command.

mosquitto_pub -t dualssh/test -m '{ "args" : ["test","test2"] }'


The syslog service transfers MQTT messages to a local syslog server.

targets = {
              # facility    option
    'user'   : ['user',     'pid'],
    'kernel' : ['kernel',   'pid']
Topic option M/O Description
title O application title (dflt: mqttwarn)
priority O log level (dflt: -1)

Where priority can be between -2 and 5 and maps to syslog levels by;

Priority Syslog Log Level
Apr 22 12:42:42 mqttest019 mqttwarn[9484]: Disk utilization: 94%


This is to send messages as a Bot to a Telegram chat. First set up a Bot and obtain its authentication token which you add to mqttwarn's configuration. You'll also need to start a chat with this bot so it's able to communicate with particular user.

Optionally you can specify parse_mode which will be used during message sending. Please, check docs for additional information.

If you have the chatId you can specify the telegram service to use the chatId directly. Warning, this will need to be the case for all the targets in this notifier!

Quickest way to get the chatid is by visiting this URL (insert your api key): and getting the id from the "from" section.

Configure the telegram service WITHOUT chatId:

timeout = 60
parse_mode = 'Markdown'
targets = {
   #        First Name or @username or #chat_id
   'j01' : [ 'First Name' ],
   'j02' : [ '@username' ],
   'j03' : [ '#chat_id' ]

Configure the telegram service WITH chatid:

timeout = 60
parse_mode = 'Markdown'
use_chat_id = True
targets = {
    #       chatId (in quotes)
    'j01' : ['123456789']

Possible issue:

  • If First name or @username was specified as target, plugin will call getUpdates to get chat_id but this call returns only last 100 messages; if you haven't spoken to your Bot recently it may well be possible we can't find the chat-id associated with you. If chat_id is known, it can be set as target using # sign.



The thingspeak service publishes data to using the thingspeak API.

targets = {
                   #API WRITE KEY       field      optional builddata=true/false
    'field1'   : [ 'XXYYZZXXYYZZXXYY', 'field1' , 'true' ],
    'field2'   : [ 'XXYYZZXXYYZZXXYY', 'field2' ],
    'composite': [ 'XXYYZZXXYYZZXXYY', [ 'temp', 'hum' ] ]

Using builddata=true you can build an update with multiple fields in one update. Using this function no direct update is performed. Only with the next update without builddata=true all entries are sent (e.g. when multiple sensors are updating different topics, then you can do the build the data and submit when the last sensor is sending the data).

Supply an ordered list of message data field names to extract several values from a single message (e.g. { "temp": 10, "hum": 77 }). Values will be assigned to field1, field2, etc in order.

Note: Use the field as per the example (lower case, 'field1' with the last digit being the field number).


The tootpaste service is for posting to the Mastodon social network.

targets = {
             # clientcreds, usercreds, base_url
    'uno'  : [ 'a.client',  'a.user', '' ],

The specified clientcreds and usercreds are paths to files created with the service, as follows:

python services/ '' '' 'xafa5280890' warnme su03-a.client su03-a.user

The arguments, in order:

  1. base URL (e.g.
  2. your e-mail address
  3. the password corresponding to the e-mail address
  4. the client name (name of the posting program)
  5. the clientcreds file
  6. the usercreds file.

The two last files are created and should be protected from prying eyes.

tootpaste (Mastodon)

tootpaste requires a pip install (


targets = {
             # Account SID            Auth Token            from              to
   'hola'  : [ 'ACXXXXXXXXXXXXXXXXX', 'YYYYYYYYYYYYYYYYYY', "+15105551234",  "+12125551234" ]

Twilio test



Notification of one or more Twitter accounts requires setting up an application at For each Twitter account, you need four (4) bits which are named as shown below.

Upon configuring this service's targets, make sure the four (4) elements of the list are in the order specified!

targets = {
  'janejol'   :  [ 'vvvvvvvvvvvvvvvvvvvvvv',                              # consumer_key
                   'wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww',          # consumer_secret
                   'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx',  # access_token_key
                   'zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz'           # access_token_secret

a tweet



The websocket service can be used to send data to a websocket server defined by its uri. ws:// or wss:// schemas are supported.

targets = {
        # targetid        : [ 'wsuri']
        'wssserver' : [ 'ws://localhost/ws' ],



This service allows for on-screen notification pop-ups on XBMC instances. Each target requires the address and port of the XBMC instance (:), and an optional username and password if authentication is required.

targets = {
                          # host:port,           [user], [password]
    'living_with_auth' :  [ '', 'xbmc', 'xbmc' ],
    'bedroom_no_auth'  :  [ '' ]
Topic option M/O Description
title O notification title
image O notification image URL (example)


The xmpp service sends notification to one or more XMPP (Jabber) recipients.

sender = 'mqttwarn@jabber.server'
password = 'Password for sender'
targets = {
    'admin' : [ 'admin1@jabber.server', 'admin2@jabber.server' ]

Targets may contain more than one recipient, in which case all specified recipients get the message.


  • XMPP (Jabber) accounts (at least one for the sender and one for the recipient)
  • xmpppy


The xively service can send a subset of your data to Xively per defined feedid.

apikey = '1234567890abcdefghiklmnopqrstuvwxyz'
targets = {
        # feedid        : [ 'datastream1', 'datastream2']
        '1234567' : [ 'temperature', 'waterlevel' ],
        '7654321' : [ 'dataItemA' ]

Publishing the following JSON message will add a datapoint to the temperature and waterlevel channel of your xively feed 1234567 (humidity will be ignored, as it's not defined in the xively configuration above):

mosquitto_pub -t "osx/json" -m '{"temperature":15,"waterlevel":100,"humidity":35}'



The zabbix service serves two purposes:

  1. it can create a Zabbix host on-the-fly via Low-level Discovery (LLD)
  2. it can send an item/value pair to a Zabbix trapper


To create an appropriate discovery host, in Zabbix:

  • Configuration->Hosts->Create host (mqttwarn01)
  • Configuration->Discovery->Create discovery rule
    • Name: MQTTwarn (any suitable name)
    • Type: Zabbix trapper
    • Key: mqtt.discovery (this must match the configured discovery_key, which defaults to mqtt.discovery)
    • Allowed hosts:, (example)

The target and topic configuration look like this:

host = "mqttwarn01"  # an existing host configured in Zabbix
discovery_key = "mqtt.discovery"
targets = {
            # Trapper address   port
    't1'  : [ '', 10051 ],

alldata = ZabbixData()
targets = zabbix:t1

alldata = ZabbixData()
targets = zabbix:t1

A transformation function in alldata is required to extract the client's name from the topic, and for #1, to define a "host alive" item key in Zabbix.

# If the topic begins with zabbix/clients we have a host going up or down
# e.g. "zabbix/clients/jog03" -> "jog03"
#   extract client name (3rd part of topic)
#   set status key (e.g. 'host.up') to publish 1/0 on it (e.g during LWT)
# if the topic starts with zabbix/item we have an item/value for the host
# e.g. "zabbix/item/jog03/time.stamp" -> "jog03"
#   extract client name (3rd part of topic)

def ZabbixData(topic, data, srv=None):
    client = 'unknown'
    key = None
    status_key = None

    parts = topic.split('/')

    ''' What we call 'client' is in fact a "Zabbix Host", i.e. the name of a
        host configured with items; it it not the name/address of the machine on
        which Zabbix server runs. So, in the UI: Configuration -> Create host '''

    client = parts[2]

    if topic.startswith('zabbix/clients/'):
        status_key = 'host.up'

    ''' This "key" is actually an LLD item which we've pre-created in the Zabbix
        UI. Configuration->Hosts->Discovery->Item prototypes->Create item prototype
	   Name: MW client $1
	   Type: Zabbix trapper
	   Type: text (can be any suitable type)

	Publishing a value with
	$ mosquitto_pub -t zabbix/item/mqttwarn01/[m02] -m 'stormy'
	will mean that we'll use the client "mqttwarn01" (see previously) and
	the item named "[m02]" which is the name of a previously
	discovered item.

    if topic.startswith('zabbix/item/'):
        key = parts[3]

    return dict(client=client, key=key, status_key=status_key)

Creating Custom Service Plugins

Creating new plugins is rather easy, and I recommend you take the file plugin and start from that.

Plugins are invoked with two arguments (srv and item). srv is an object with some helper functions, and item a dict which contains information on the message which is to be handled by the plugin. item contains the following elements:

item = {
    'service'       : 'string',       # name of handling service (`twitter`, `file`, ..)
    'target'        : 'string',       # name of target (`o1`, `janejol`) in service
    'addrs'         : <list>,         # list of addresses from SERVICE_targets
    'config'        : dict,           # None or dict from SERVICE_config {}
    'topic'         : 'string',       # incoming topic branch name
    'payload'       : <payload>       # raw message payload
    'message'       : 'string',       # formatted message (if no format string then = payload)
    'data'          : None,           # dict with transformation data
    'title'         : 'mqttwarn',     # possible title from title{}
    'priority'      : 0,              # possible priority from priority{}


In addition to passing the payload received via MQTT to a service, mqttwarn allows you do do the following:

  • Transform payloads on a per/topic basis. For example, you know you'll be receiving JSON, but you want to warn with a nicely formatted message.
  • For certain services, you can change the title (or subject) of the outgoing message.
  • For certain services, you can change the priority of the outgoing message.

Consider the following JSON payload published to the MQTT broker:

mosquitto_pub -t 'osx/json' -m '{"fruit":"banana", "price": 63, "tst" : "1391779336"}'

Using format we can configure mqttwarn to transform that JSON into a different outgoing message which is the text that is actually notified. Part of said format looks like this in the configuration file, and basically specifies that messages published to osx/json should be transformed as on the right-hand side.

format = "I'll have a {fruit} if it costs {price}"

(Embedded "\n" are converted to newlines on output.)

The result is:

OSX notifier

You associate MQTT topic branches to applications in the configuration file (copy mqttwarn.ini.sample to mqttwarn.ini for use). In other words, you can accomplish, say, following mappings:

  • PUBs to owntracks/jane/iphone should be notified via Pushover to John's phone
  • PUBs to openhab/temperature should be Tweeted
  • PUBs to home/monitoring/alert/+ should notify Twitter, Mail, and Prowl

See details in the config sample for how to configure this script. The path to the configuration file (which must be valid Python) is obtained from the MQTTWARNINI environment variable which defaults to mqttwarn.ini in the current directory.

Advanced features

JSON output serialization

When receiving JSON data like {"data": {"humidity": 62.18}}, you might want to extract values using the format mechanism before forwarding it to other data sinks, like

format = "{data}"

However, the outcome will be the string-serialized form of the Python representation: {u'humidity': 62.18}, which could not be what you want if your data sink is expecting JSON format again.

To achieve this, you should use appropriate type coercion before formatting, like

format = "{data!j}"

This will serialize the formatted data to JSON format appropriately, so the outcome will be {"humidity": 62.18}.

Transformation data

mqttwarn can transform an incoming message before passing it to a plugin service. On each message, mqttwarn attempts to decode the incoming payload from JSON. If this is possible, a dict with transformation data is made available to the service plugins as

This transformation data is initially set up with some built-in values, in addition to those decoded from the incoming JSON payload. The following built-in variables are defined in

  'topic'         : topic name
  'payload'       : topic payload
  '_dtepoch'      : epoch time                  # 1392628581
  '_dtiso'        : ISO date (UTC)              # 2014-02-17T10:38:43.910691Z
  '_dthhmm'       : timestamp HH:MM (local)     # 10:16
  '_dthhmmss'     : timestamp HH:MM:SS (local)  # 10:16:21

Any of these values can be used in format to create custom outgoing messages.

format = I'll have a {fruit} if it costs {price} at {_dthhmm}

Using functions to replace incoming payloads

Consider the following configuration snippet in addition to the configuration of the mqtt service shown above:

def lookup_data(data, srv=None):
    if type(data) == dict and 'fruit' in data:
            return "Ananas"
    return None

Then, in the section defining the topic we listen on:

#format =  Since when does a {fruit} cost {price}?
format =  lookup_data()

We've replaced the formatmap entry for the topic by a function which you define within the functions file you configure as functions in mqttwarn.ini configuration file. These functions are invoked with decoded JSON data passed to them as a dict. The string returned by the function returned string replaces the outgoing message:

in/a1 {"fruit":"pineapple", "price": 131, "tst" : "1391779336"}
out/food Ananas
out/fruit/pineapple Ananas

If a function operating on a message (i.e. within format =) returns None or an empty string, the target notification is suppressed.

The optional srv is an object with some helper functions. In particular, these allow us to use mqttwarn's logging and MQTT publish functions, as in this example:

def p01Format(data, srv):
    s = "p01-HOLA""+++++++++++ HUHU")

    srv.mqttc.publish("p01/RESPonse", s, qos=0, retain=False)

    return s

Be advised that if you MQTT publish back to the same topic which triggered the invocation of your function, you'll create an endless loop.

Incorporating topic names into transformation data

An MQTT topic branch name contains information you may want to use in transformations. As a rather extreme example, consider the OwnTracks program (the artist formerly known as MQTTitude).

When an OwnTracks device detects a change of a configured waypoint or geo-fence (a region monitoring a user can set up on the device), it emits a JSON payload which looks like this, on a topic name consisting of owntracks/_username_/_deviceid_:

owntracks/jane/phone -m '{"_type": "location", "lat": "52.4770352" ..  "desc": "Home", "event": "leave"}'

In order to be able to obtain the username (jane) and her device name (phone) for use in transformations (see previous section), we would ideally want to parse the MQTT topic name and add that to the item data our plugins obtain. Yes, we can.

An optional datamap in our configuration file defines the name of a function we provide, also in the configuration file, which accomplishes that.

datamap = OwnTracksTopicDataMap()

This specifies that when a message for the defined topic owntracks/jane/phone is processed, our function OwnTracksTopicDataMap() should be invoked to parse that. (As usual, topic names may contain MQTT wildcards.)

The function we define to do that is:

def OwnTracksTopicDataMap(topic):
    if type(topic) == str:
            # owntracks/username/device
            parts = topic.split('/')
            username = parts[1]
            deviceid = parts[2]
            deviceid = 'unknown'
            username = 'unknown'
        return dict(username=username, device=deviceid)
    return None

The returned dict is merged into the transformation data, i.e. it is made available to plugins and to transformation rules (format). If we then create the following rule

format = {username}: {event} => {desc}

the above PUBlish will be transformed into

jane: leave => Home

Merging more data

The optional alldata function you write and configure on a per/topic basis, is passed the message topic, its data and an optional srv object. This function should return a dict (or None) of data which is merged into the whole list of transformation data. This expands on the two other transformation functions to make topic and the message's payload available simultaneously.

Accessing Nested JSON Nodes

Within templates and formats, you can refer only to the top-level names of an incoming JSON message. To do otherwise currently requires an alldata function, which returns a new message to completely replace the old one.

For example, say you are receiving messages from a temperature sensor running Tasmota, and you wish to convert them into InfluxDB line format.

The JSON will look like this:

    "Time": "2018.02.01 21:29:40",
    "DS18B20": {
      "Temperature": 19.7
    "TempUnit": "C"

Temperature cannot be referenced directly within a format. Instead the following code will extract the nested value, and will also convert the timestamp into a different format:

import ast
import time
from datetime import datetime

def standard_values(topic, payload):
    ts = datetime.strptime(payload["Time"], "%Y.%m.%d %H:%M:%S")
    millis = long(time.mktime(ts.timetuple()) * 1000)
    return dict( Topic = topic, Timestamp = millis )

def ds18b20_values(topic, data, srv=None):
    payload = ast.literal_eval(data["payload"])
    d = standard_values(topic, payload)
    d.update(Temperature = payload["DS18B20"]["Temperature"])
    return d

Apply it to a topic in mqttwarn.ini:

targets = log:info
alldata = ds18b20_values()
format  = mqttwarn,Topic={Topic} Temperature={Temperature} {Timestamp}

Which results in:

2018-07-19 22:00:24,452 DEBUG [mqttwarn] Message received on tasmota/temp/ds/1: { "Time": "2018.02.01 22:48:39", "DS18B20": { "Temperature": 19.7 }, "TempUnit": "C" }
2018-07-19 22:00:24,453 DEBUG [mqttwarn] Section [tasmota/temp/ds/+] matches message on tasmota/temp/ds/1. Processing...
2018-07-19 22:00:24,459 DEBUG [mqttwarn] Message on tasmota/temp/ds/1 going to log:info
2018-07-19 22:00:24,459 DEBUG [mqttwarn] New `log:info' job: tasmota/temp/ds/1
2018-07-19 22:00:24,459 DEBUG [mqttwarn] Processor #0 is handling: `log' for info
2018-07-19 22:00:24,460 DEBUG [log] *** MODULE=services/log.pyc: service=log, target=info
2018-07-19 22:00:24,460 INFO  [log] mqttwarn,Topic=tasmota/temp/ds/1 Temperature=19.7 1517525319000

Using transformation data in other contexts

Beside using the transformation data dictionary in format to create custom outgoing messages, it can be used in other contexts as well. Let's have a look at different ways this can be used throughout mqttwarn.

Topic targets

By incorporating transformation data into topic targets, we can make mqttwarn dispatch messages dynamically based on the values of the transformation data dictionary.

To get an idea about how this works, let's define a placeholder variable inside the targets directive of a topic section in the mqttwarn.ini configuration file:

topic   = test/topic-targets-dynamic
format  = Something {loglevel} happened! {message}
targets = log:{loglevel}

When sending this value through a JSON encoded message or by computing it through the datamap or alldata transformation machinery, it will get interpolated into the designated topic target. Example:

mosquitto_pub -t test/topic-targets-dynamic -m '{"loglevel": "crit", "message": "Nur Döner macht schöner!"}'

This will issue the following message into the log file:

2016-02-14 18:09:34,822 CRITICAL [log] Something crit happened! Nur Döner macht schöner!

While this little example might feel artificial, there are more meaningful use cases like determining the recipient address of smtp or xmpp receivers through information from topic names or message payloads. Please have a look at Incorporate topic names into topic targets for a more sensible example.

Filtering notifications

A notification can be filtered (or suppressed) using a custom function.

An optional filter in our configuration file, defines the name of a function we provide. The function is provided in another file, as specified by the functions directive in the configuration file.

filter = owntracks_filter()

This specifies that when a message for the defined topic owntracks/jane/phone is processed, our function owntracks_filter() should be invoked to parse that. The filter function should return True if the message should be suppressed, or False if the message should be processed. (As usual, topic names may contain MQTT wildcards.)

The function we define to do that is:

def owntracks_filter(topic, message):
    return message.find('event') == -1

This filter will suppress any messages that do not contain the event token. This filter goes in the file specified by the functions directive.


Instead of formatting output with the format specification as described above, mqttwarn has provision for rendering the output message from Jinja2 templates, probably particularly interesting for the smtp or nntp and file targets.

Consider the following example topic configuration, where we illustrate using a template instead of format (which is commented out).

targets = nntp:jpaa
; format = {name}: {number} => {_dthhmm}
template = demo.j2

mqttwarn loads Jinja2 templates from the templates/ directory relative to the configured directory. Assuming we have the following content in the file templates/demo.j2

    this is a comment
    in Jinja2
    See for information
    on Jinja2 templates.
{% set upname = name | upper %}
{% set width = 60 %}
{% for n in range(0, width) %}-{% endfor %}

Name.................: {{ upname }}
Number...............: {{ number }}
Timestamp............: {{ _dthhmm }}
Original payload.....: {{ payload }}

could produce the following message, on any target which uses this configuration.

Name.................: JANE JOLIE
Number...............: 47
Timestamp............: 19:15
Original payload.....: {"name":"Jane Jolie","number":47, "id":91}

One of the template variables you may be interested in is called {{ payload }}; this carries the original MQTT message in it. Also, if the payload was JSON, those are available also (as shown in the above example), together with all the other transformation data.

If the template cannot be rendered, say, it contains a Jinja2 error or the template file cannot be found, etc., the original raw message is used in lieu on output.

As mentioned already, we think this is useful for targets which expect a certain amount of text (file, smtp, and nntp come to mind).

Use of this feature requires Jinja2, but you don't have to install it if you don't need templating.

Periodic tasks

mqttwarn can use functions you define in the file specified [defaults] section to periodically do whatever you want, for example, publish an MQTT message. There are two things you have to do:

  1. Create the function
  2. Configure mqttwarn to use that function and specify the interval in seconds

Assume we have the following custom function defined:

def pinger(srv=None):
    srv.mqttc.publish("pt/PINGER", "Hello from mqttwarn!", qos=0)

We configure this function to run every, say, 10 seconds, in the mqttwarn.ini, in the [cron] section:

pinger = 10.5

Each keyword in the [cron] section specifies the name of one of your custom functions, and its float value is an interval in seconds after which your custom function (pinger() in this case) is invoked. Your function has access to the srv object (which was described earlier).

Function names are to be specified in lower-case characters.

If you want to run the custom function immediately after starting mqttwarn instead of waiting for the interval to elapse, you might want to configure:

pinger = 10.5; now=true


This section contains some examples of how mqttwarn can be used with some more complex configurations.

Low battery notifications

By subscribing to your OwnTracks topic and adding the following custom filter you can get mqttwarn to send notifications when your phone battery gets below a certain level;

def owntracks_battfilter(topic, message):
    data = dict(json.loads(message).items())
    if data['batt'] is not None:
        return int(data['batt']) > 20
    return True

Now simply add your choice of target(s) to the topic's section and a nice format string and you are done;

targets = pushover, xbmc
filter = owntracks_battfilter()
format = My phone battery is getting low ({batt}%)!

Producing JSON

Assuming we get, from an Arduino, say, a single numerical value in the payload of an MQTT message, we want to generate JSON with some additional fields. Using a Jinja2 template for the task, does exactly what we need:

The following target configuration invokes the template:

targets = log:info, http:graylog2
template = temp2json.json

The Jinja2 template looks like this:

    We expect a single numeric temperature value in `payload'
    Return JSON suitable for Graylog2 (requires host and short_message)

    Define a data structure in Jinja2 and return it as a JSON string.
    Note how transformation data (produced within mqttwarn) is used:
    the variables `_dtiso' and `payload' contain a timestamp and our
    payload respectively.
{% set data = {
	'host'		: topic,
	'short_message'	: "Heat " + payload,
	'tst'		: _dtiso,
	'temperature'	: payload,
	'woohooo'	: 17,
{{ data | jsonify }}

and an example JSON string returned by that template is then passed to our configured targets thusly:

"host": "arduino/temp", "woohooo": 17, "tst": "2014-04-13T09:25:46.247150Z", "temperature": "22", "short_message": "Heat 22"}


"MQTT" is a trademark of the OASIS open standards consortium, which publishes the MQTT specifications.