Add support to publish data via different query

[NiklasCi]

This PR adds support to publish data via the datasource by sending a different payload.
This can be used by plugins like Buttons Panel or Data Manipulation.

Publish timeouts after 1s and subscribe timeouts 1s after publish was successful.

Schema of query:

interface Query { topic string // topic to publish payload to payload object // a js/json object that contains the publish message response string // (Optional): a topic to listen for a response }

Example of a query:

query: { topic: "cmd/send/values", payload: { value1: "Hallo", value2: 12.34 }, response: "response/from/send" }

The returned response from the query contains the reponse of the mqtt command under a new frame with name Response and a field Body where the field values contain the responded message.
Note: I only tested json response messages.

[DonatoD]

can it work with plugin like htmlgraphic https://grafana.com/grafana/plugins/gapit-htmlgraphics-panel/

[NiklasCi]

https://grafana.com/grafana/plugins/gapit-htmlgraphics-panel/

If this plugin supports getting the backend server and the access to the grafana api sure.
You can send a query via grafana datasource api: https://grafana.com/docs/grafana/latest/developers/http_api/data_source/#query-a-data-source

Should look like this:

POST /api/ds/query HTTP/1.1 Accept: application/json Content-Type: application/json { "queries":[ { "refId":"1", "datasource":{ "uid":"MQTT-UID" // need to be known }, "topic": "cmd/send/values", "payload": { "value1": "Hallo", "value2": 12.34 }, "response": "response/from/send" } ], } 

[DonatoD]

Thanks. I'm not that expert on this stuff, so I need to study all this more in details. But the html graphic panel allow you to write in javascript, so I think it should works, shouldn't it?

[NiklasCi]

Thanks. I'm not that expert on this stuff, so I need to study all this more in details. But the html graphic panel allow you to write in javascript, so I think it should works, shouldn't it?

Yes as long as you get the backend server. There are helper functions under @grafana/runtime.
For example getDataSourceSrv() or getbackendSrv(). Maybe cehckout iof you can access them in the html panel.

If so you can publish mqtt data.

[DonatoD]

Thanks so much. I'll give it a look

[excalq]

Would love to make use of this. Is there a possibility of this being merged?

[NiklasCi]

@toddtreece Sorry to ping you. I want to know what you thing about the idea to make publishing via this datasource possible? I saw that with Grafana 11.6 there are now actions that could make use of it. We using this functionality now over a year without any problems.

Following things i would change in the upcoming days/weeks before this could be reviewed/merged:

• Resolve conflicts and make use of new go functionality like errgroup if possible,
• Make this an opt-in functionality, so that it does not break anything by default.

[zoltanbedi]

Hey @NiklasCi,
I see you are still interested to merge this. I'll take a look at it shortly.

[NiklasCi]

Hey @NiklasCi, I see you are still interested to merge this. I'll take a look at it shortly.

Hey @zoltanbedi. That would be awesome. We using this now over a year in production on multiple grafana instances, without any problems so far.

For testing i can't provide my own panel but the Button Panel should work.