Added a on_connect callback

jamiebegin / metrics2mqtt

Publish cross-platorm system performance metrics to a MQTT broker.

MIT License

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Added a on_connect callback #5

Closed stegmannb closed 4 years ago

stegmannb commented 4 years ago

This PR tries to fix #4 and adds on_connect callback. If the connection could not be established an error message is logged.

It also fixes a problem I encountered with HomeAssistant autodiscovery where the config topic gets lost, because it is published before the connection is established. This may be because I use authentication or the broker is running on a slow system.

This is the first I am trying to contribute to an open source project and there may very well be a more elegant solution, so any feedback is appreciated.

jamiebegin commented 4 years ago

Thank you for the PR!

I was going to change the log level to error but then I saw the subsequent commit.
You're directly calling sys.exit() which bypasses the cleanup method. I don't see this being a problem right now because everything the cleanup does is predicated on being connected to the broker already anyhow. And I don't foresee the need to ever open resources ahead of trying to connect to the broker.

I'll go ahead and merge this. Thanks again for the contribution!