new feature mqtt_filter to start a command and give feedback

Author: joerggollnick

HANDBOOK.md

@@ -321,12 +321,12 @@ _mqttwarn_ supports a number of services (listed alphabetically below):
 * [ionic](#ionic)
 * [azure_iot](#azure_iot)
 * [irccat](#irccat)
-* [launch](#launch)
 * [linuxnotify](#linuxnotify)
 * [log](#log)
 * mastodon (see [tootpaste](#tootpaste))
 * [mattermost](#mattermost)
 * [mqtt](#mqtt)
+* [mqtt_filter](#mqtt_filter)
 * [mqttpub](#mqttpub)
 * [mysql](#mysql)
 * [mysql_dynamic](#mysql_dynamic)
@@ -1286,30 +1286,6 @@ targets = {
 Requires:
 * gobject-introspection Python bindings
 
-### `launch`
-
-The `launch` target excutes the specified program and its arguments. It is similar
-to `pipe` but it doesn't open a pipe to the program. It provides stdout as response
-to configured queue.
-Example use cases are f.e. IoT buttons which publish a message when they are pushed
-and the excute an external program. It is also a clone of [mqtt-launcher](https://github.com/jpmens/mqtt-launcher).
-
-```ini
-[config:launch]
-targets = {
-              # full_topic, topic[0], topic[1], args[0], .....
-   'touch'    : [ None,0,0,'touch', '/tmp/executed' ],
-   'fritzctl' : [ None,0,0,'/usr/bin/fritzctl', 'temperature', "{args[0]}", "{args[1]}" ]
-   'backup'   : ["response/{topic[1]}/{topic[2]}",0,0,'/usr/bin/sudo','/usr/sbin/dirvish','--vault', "{args[0]}" ],
-   }
-```
-
-To pass the published data (json args array) to the command, use `{args[0]}` and `{args[1]}` which then gets replaced. Message looks like `'{ "args" : ["' + temp + '","' + room + '"] }'` for `fritzctl`.
-outgoing_topic is constructed by parts of incoming topic or as full_incoming topic.
-
-Note, that for each message targeted to the `launch` service, a new process is
-spawned (fork/exec), so it is quite "expensive".
-
 ### `log`
 
 The `log` service allows us to use the logging system in use by _mqttwarn_
@@ -1448,6 +1424,71 @@ This shows the currently full configuration possible. Global values from the
 authentication (`auth`) or (`tls`) you may omit those sections. (The `defaults`
 section must exist.)
 
+### `mqtt_filter`
+
+The `mqtt_filter` target executes the specified program and its arguments. It is similar
+to `pipe` but it doesn't open a pipe to the program. It provides stdout as response
+to a configured queue.
+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 clone of [mqtt-launcher](https://github.com/jpmens/mqtt-launcher).
+With no response configured it acts like `execute` with multiple arguments.
+
+To pass the published data (json args array) to the command, use `{args[0]}` and `{args[1]}` which then gets replaced. Message looks like `'{ "args" : ["' + temp + '","' + room + '"] }'` for `fr
+itzctl`.
+
+outgoing_topic is constructed by parts of incoming topic or as full_incoming topic.
+
+```ini
+[config:mqtt_filter]
+targets = {
+   # full_topic, topic[0], topic[1], args[0], .....
+   'touch'    : [ None,0,0,'touch', '/tmp/executed' ],
+   'fritzctl' : [ None,0,0,'/usr/bin/fritzctl','--loglevel=ERROR','temperature', "{args[0]}", "{args[1]}" ]
+   'backup'   : ["response/{topic[1]}/{topic[2]}",0,0,'/usr/bin/sudo','/usr/sbin/dirvish','--vault', "{args[0]}" ],
+   }
+```
+
+Use case for fritzctl is to change the requested temperature for a connected thermostat.
+Topic is constructed as /home/{room}/temperature/{action}.
+
+```
+def TemperatureConvert( data=None, srv=None):
+
+    # optional debug logger
+    if srv is not None:
+        srv.logging.debug('data={data}, srv={srv}'.format(**locals()))
+
+    topic = str( data.get('topic','') )
+
+    # init
+    room = ''
+    action = 'status'
+
+    # /home/{room}/temperature/{action}
+    parts = topic.split('/')
+
+    for idx, part in enumerate( parts ):
+         if idx == 1:
+             room = part
+
+         if idx == 3:
+             action = part
+
+    temp = str( data.get('payload','sav') )
+    if temp == '':
+        temp = 'sav'
+
+    if action == 'set':
+        cmd = '{ "args" : ["' + temp + '","' + room + '"] }'
+
+    return cmd
+```
+
+Use case for backup is to run a dirvish backup triggered by a simple mqtt message.
+
+Note, that for each message targeted to the `mqtt_filter` service, a new process is
+spawned (fork/exec), so it is quite "expensive".
+
 ### `mqttpub`
 
 This service publishes a message to the broker _mqttwarn_ is connected to. (To

mqttwarn/services/launch.py mqttwarn/services/mqtt_filter.pymqttwarn/services/launch.py renamed to mqttwarn/services/mqtt_filter.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
-__author__    = 'Tobias Brunner <tobias()tobru.ch>'
+__author__    = 'Joerg Gollnick <github+mqttwarn()wurzelbenutzer.de>'
 __copyright__ = 'Copyright 2016 Tobias Brunner / 2021 Joerg Gollnick'
 __license__   = """Eclipse Public License - v 1.0 (http://www.eclipse.org/legal/epl-v10.html)"""
 
@@ -14,7 +14,7 @@ def plugin(srv, item):
 
     srv.logging.debug("*** MODULE=%s: service=%s, target=%s", __file__, item.service, item.target)
 
-    # same as for ssh - extract args from json item.message
+    # same as for ssh
     args=json.loads(item.message)["args"]
 
     if type(args) is list and len(args) == 1:
@@ -25,13 +25,17 @@ def plugin(srv, item):
     elif type(args) is str or type(args) is unicode:
         args=(quote(args),)
 
+    # parse topic
     topic=list(map( lambda x: quote(x), item.topic.split('/') ))
-    outgoing_topic = item.addrs[0].format(full_topic=quote(item.topic),topic=topic)
+
+    # replace palceholders args[0], args[1] ..., full_topic, topic[0],
+    outgoing_topic = item.addrs[0].format(args=args,full_topic=quote(item.topic),topic=topic)
     qos            = item.addrs[1]
     retain         = item.addrs[2]
     addrs          = item.addrs[3:]
-    # replace args[0], args[1] ...
-    cmd = [i.format(args=args) for i in addrs]
+
+    cmd = [i.format(args=args, full_topic=quote(item.topic),topic=topic) for i in addrs]
+
     srv.logging.debug("*** MODULE=%s: service=%s, command=%s outgoing_topic=%s", __file__, item.service, str( cmd ),outgoing_topic)
 
     try: