Use Automation for MQTT Autodiscovery

Configuration
1

What I try to accomplish

I want HA to publish a “config” update through the MQTT service when an MQTT device is connecting.

What is working

I can manually update the topic:

homeassistant/switch/in9408_garden/alarm_area_red/config

with the following JSON payload to use the MQTT auto-discovery to configure my device:

{
    "device": {
        "identifiers": "in9408_garden",
        "manufacturer": "INSTAR Deutschland GmbH",
        "model": "INSTAR 2k+ IN-9408 WLAN",
        "name": "IN-9408 2k+ Garden",
        "configuration_url": "http://192.168.2.115:80"
    },
    "availability": {
      "topic": "cameras/115/status/testament",
      "payload_available": "{\"val\":\"alive\"}",
      "payload_not_available": "{\"val\":\"dead\"}"
    },
    "object_id":"in9408_garden_alarm_area_red",
    "unique_id": "in9408_garden_alarm_area_red",
    "name": "IN-9408 2k+ Garden Alarm Area Red",
    "icon": "mdi:camera-metering-matrix",
    "command_topic": "cameras/115/alarm/areas/red/enable",
    "payload_on": "{\"val\":\"1\"}",
    "payload_off": "{\"val\":\"0\"}",
    "state_topic": "cameras/115/status/alarm/areas/red/enable",
    "state_on": 1,
    "state_off": 0,
    "value_template": "{{ value_json.val }}",
    "qos": 1
}

What doesn’ t work

I want to add an automation that publishes the above update whenever my devices Last-Will topic indicates that the device was connected - and I am getting the following error message when I run the action:

2022-08-30_18-02
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Anyone ran into this issue before?

2

Just guessing…

It might need to converted to a “literal” (or from a literal, idk)

“{{ value_json.val }}” change to

\"{{ value_json.val }}\"
3

Hey Has,

thank you for your reply - but unfortunately I am still getting the same error:

2022-08-30_19-08
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4

This might be of help. If you do a “Run Action” in the automation editor, it skips the triggers/conditions and just starts running your actions. If your actions fundamentally require information from an incoming trigger (like, say, decoding an incoming JSON message), then your automation won’t work when fired manually.

edit: just to be clear, you’ll probably need to fire off that MQTT message in order to test your automation correctly. Also, you’ll probably want a default value declared for your template so you don’t get errors if it gets triggered in some other way (like somebody clicked “run actions”).

5

Hi luma,

is_defined sounded promising - I tried it and it does not change the error message. The script is self-contained. value_json.val is an instruction HA is supposed to use once the device is set up (which means that HA subscribed to the given MQTT topics).

When the script is run there is no value_json.val yet - this instruction probably needs to be send as type string. So I think Has has the right idea - but I am not sure why it does not work.

But I am also not sure what happens when I run this script - compared to what happens when I send the MQTT update manually :thinking:

6

value_jason.val is undefined when you press “RUN ACTIONS” in the automation editor, because there was no JSON being sent to the automation. It will never work when you press RUN ACTIONS for this reason. If you add a default value you can get rid of that error, but it still isn’t going to work because once again you don’t have a JSON that is being sent to your automation for it to Do Things with when you press RUN ACTIONS.

So, give yourself a default, and also expect to manually send MQTT messages for your test/dev process because RUN ACTIONS will not do what you are expecting.

7

I should also note: it’s technically possible to capture the RUN ACTIONS via a condition {{ trigger.platform is none }}, so if you really want to test via RUN ACTIONS, you can create a separate code path that is followed when somebody presses that button in the automation editor.

8

Hi Luma,

I spend some thinking about this issue. And this is not the solution. Your option is for a script that - when run in production - will receive data that defines this variable. But this is not going to happen in my script.

What is going wrong

I define an action that says:

Here is an instruction. DO NOT READ THIS. Just forward it to the MQTT broker. Someone will pick it up from there and will know what to do with it.

I run the script and get an error:

I Read the instruction. Don’t know what it means. I am not going to forward it. Break.

What I would need is a way to mask the variable. So the script does not see it. But it has to be readable again for the HA MQTT auto-discovery service (that will pick it up from the broker). I thought maybe there is a way to use templating to generate the variable on run-time. So that it is not being executed. But I did not find a solution for it yet.

What I am doing now

  1. I wrote a Python mqtt client.
  2. I use a shell script to run the client (I had issue getting the Python file to run using python_scripts I guess it is because of the isolation/virtEnv).
  3. The client then updates all the MQTT configuration topics.
  4. And the shell script then becomes the action for my automation.

Result: My MQTT camera connects to the Home Assistant MQTT broker and is immediately added as a device with a bunch of functions:

2022-09-02_18-14
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This was an interesting deep-dive into HA for me :slight_smile: But it is a bit convoluted…

1 Like
9

I have been playing around with this for my addon.
It is abit messy at the moment, but I can add the device sensors from the addon with bashio scripts

I cant get it to read my $mqtt_data yet… having trouble breaking the string up. But I can send all the sensors to mqtt.

The mqtt integration does not seem to like disabled sensors much though. If they are disabled from the script they can’t be deleted by the mqtt integration if they have never been enabled

You also may need to set you default() in your value templates

\"{{ value_json.$value | default() }}\",

"MQTT_Data": "Timestamp,SunRise,SunSet,InvSerial,InvName,InvTime,InvStatus,InvSwVer",


if bashio::var.has_value "$MQTT_Data" 'InvTime' ; then
   value='InvTime'
   describe='SMA Time Inverter'
   mdi_icon='mdi:clock'
   devClass=
   stClass=
   UoM=
   EnabDef='true' 
   ent_cat='diagnostic'
   
   bashio::log.info Setting Up "$value"
   
   /usr/bin/mosquitto_pub -h "$MQTT_Host" -u "$MQTT_User" -P "$MQTT_Pass" -t homeassistant/sensor/sbfspot_"$PLANTNAME"/sbfspot_"$InvSerial""$value"/config -m "{\"name\": \"$describe\", \"state_topic\": \"homeassistant/sbfspot_$PLANTNAME/sbfspot_$InvSerial\", \"value_template\": \"{{ value_json.$value | default() }}\", \"unique_id\": \"$InvSerial"'_'"$value\", \"enabled_by_default\": \"$EnabDef\", \"entity_category\": \"$ent_cat\", \"icon\": \"$mdi_icon\", \"device\": { \"identifiers\": [\"$(bashio::addon.name)""-Sensors\"], \"name\": \"HAOS-SBFspot\", \"model\": \"$InvType\", \"manufacturer\": \"SMA\", \"sw_version\": \"$InvSwVer\" }}" "$debugMQTT" "$RoK"
   else 
     bashio::log.yellow Skipping "${value}"
fi

if bashio::var.equals "${MQTT_Data}" 'SunRise' ; then
   value='SunRise'
   describe='SMA Sun Rise'
   mdi_icon='mdi:weather-sunny'
   devClass=
   stClass=
   UoM=
   EnabDef='true'
   ent_cat=
   
   bashio::log.info Setting Up "$value"
   
   /usr/bin/mosquitto_pub -h "$MQTT_Host" -u "$MQTT_User" -P "$MQTT_Pass" -t homeassistant/sensor/sbfspot_"$PLANTNAME"/sbfspot_"$InvSerial""$value"/config -m "{\"name\": \"$describe\", \"state_topic\": \"homeassistant/sbfspot_$PLANTNAME/sbfspot_$InvSerial\", \"value_template\": \"{{ value_json.$value | default() }}\", \"unique_id\": \"$InvSerial"'_'"$value\", \"enabled_by_default\": \"$EnabDef\", \"icon\": \"$mdi_icon\", \"device\": { \"identifiers\": [\"$(bashio::addon.name)""-Sensors\"], \"name\": \"HAOS-SBFspot\", \"model\": \"$InvType\", \"manufacturer\": \"SMA\", \"sw_version\": \"$InvSwVer\" }}" "$debugMQTT" "$RoK"
   else 
     bashio::log.yellow Skipping "${value}"
fi
10

This doesn’t fully answer your question since it doesn’t seem to work when evaluating the actual template, but from the HA docs in this page, the example they give for how a template should be passed shows this syntax:

"value_template": "{% raw %}{{ value|float }}{% endraw %}"

Wrapping the template in {% raw %} allows it to be passed onto the MQTT broker without being evaluated in the process. That said, I can’t seem to get any templates to work when using this.

11

Perhaps this post will help:
https://community.home-assistant.io/t/manually-add-mqtt-entities/264695/7