Telegraf MQTT shared topic error

Telegraf
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1

Hi,

I’m configuring the inputs.mqtt_consumer and if I set topic to:

topic = ["topic/#"]

all works fine, but if I set:

topic = ["$share/topic/#"]

all work the same but every message I receive this error on the logs

[inputs.mqtt_consumer] Error in plugin: must be an object or an array of objects

Any idea why?

inputs.mqtt_consumer configs:

[inputs.mqtt_consumer]]
  servers = ["tcp://broker:1883"]
  # topics = ["topic/#"]
  topics = ["$share/topic/#"]
  qos = 2
  connection_timeout = "30s"
  username = "username"
  password = "password"
  json_name_key = "endpoint"
  tag_keys = ["host"]
  json_string_fields = ["value"]
  data_format = "json"

docker telegraf version: telegraf:1.19

2

Hi @Renato,
Welcome to the community :slight_smile:! Correct me if I am wrong here but using the $ sign before a topic is to collect internal stats on the topic itself?

Are these stats received in a JSON structure?

3

Hi @Jay_Clifford ,
The $share is to subscribe to a shared topic(https://www.emqx.com/en/blog/introduction-to-mqtt5-protocol-shared-subscription), this way if I have multiple clients in that shared topic the broker divide the messages between them.

4

Hi @Renato,
Sorry for the late reply. I see this is an MQTT 5.0 feature. I believe the underlining lib that we are using supports: MQTT 3.1/3.1. : GitHub - eclipse/paho.mqtt.golang.

If you would like to make a feature request for MQTT 5.0 support please crate one within the Telegraf git. From there I can flag it with the maintainers to see what can be done.

5

Problem solved if puts topics = ["$share/username/topic/#"]
Is required to pass username too.