Debugging MQTT over websockets on Envoy 1.28.0

I have migrated our Envoy installation from Envoy 1.11.1 to 1.28.0, and am now also using SNI for selecting the correct certificate. A big part of that migration is upgrading the syntax of the configuration for Envoy from the v2 API to the v3 API. The upgrade went well, except for our websocket-based MQTT service…

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VerneMQ how to disconnect clients forceably per command line

There is a command vmq-admin session show which will show you the currently connected clients: Unfortunately, this output is truncated for a total width of 80 characters (no matter how many would fit) and there is currently no indication that it is. See this VerneMQ Github issue: https://github.com/vernemq/vernemq/issues/1200 To disconnect clients you need the client_id…

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Changing the mountpoint on auth_on_register webhook for VerneMQ

It is possible to pass modifiers along with the “result”: “ok” return value of your webhook for VerneMQ. The official documentation of VerneMQ gives some examples for the syntax. changing the mountpoint It is also possible to change the mountpoint, however the client_id apparently has to be passed in as well! I have raised an…

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Debugging VerneMQ connection / authentication problems for dual authentication with webhooks and vmq_diversity

TL;DR https://github.com/vernemq/vernemq/blob/master/apps/vmq_diversity/src/vmq_diversity_plugin.erl includes a statement which will block authentication / authorization through any other channels if your Lua script returns “false”: will lead to: instead of trying other plugins, as you might have assumed! In order to avoid this problem, simply do not return anything from your Lua script, if you do not want to…

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MQTT Topic Tree Design best practices, tips & examples

Generic MQTT Background With MQTT the sender and receiver are not aware of each other – the broker handles the messaging. This allows the messages to be separated in space, time, and intensity. The sender can send at the speed it wants, and the time it wants. The receiver can pick up the messages at…

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VerneMQ: econnrefused & Webhook example

Webhooks activate webhooks like this in your vernemq.conf.local (.local when running on docker, so that settings at bottom of the file will persist): plugins.vmq_webhooks = on vmq_webhooks.js_auth_on_register.hook = auth_on_register vmq_webhooks.js_auth_on_register.endpoint = http://container_picockpit:1200/example/path Note that if your webhook is not accessible (econnrefused), the db based authentication will also fail … ! If you get errors like…

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VerneMQ Docker overwrites my configuration

Situation You edit vernemq.conf, only to find that your configuration is overwritten by VerneMQ on the next start (using the official Docker container). Specifically, the section with the listeners at the end of the file is “forced upon you”. Solution VerneMQ is started using a script (start_vernemq). The script can be seen here: https://github.com/vernemq/docker-vernemq/blob/master/bin/vernemq.sh The…

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