core: RainMachine integration can no longer monitor Gen1 device after recent update

The problem

A recent Home Assistant update caused the RainMachine integration to stop being able to manage my Gen1 RainMachine device. The integration was working just fine right up until I installed a Home Assistant OS & Core update on May 3rd and it hasn’t been working properly since.

I see this in the logs…

2023-05-05 12:35:40.914 WARNING (MainThread) [homeassistant.config_entries] Config entry ‘Rainmachine’ for rainmachine integration not ready yet: Connection error while requesting data from https://10.0.0.217:443/api/4/auth/login; Retrying in background

Before installing the updates to Core and Home Assistant OS on May 3rd everything had been working fine with the RainMachine integration in terms of managing my Gen1 device. No idea what exactly changed but something did as I can’t get it working at all now.

Gen1 RainMachines have some ancient https cert that doesn’t work in modern browsers. I know that this integration previously worked fine with that but if anything changed recently in relation to that it might explain this.

What version of Home Assistant Core has the issue?

2023.5.1

What was the last working version of Home Assistant Core?

2023.4.5

What type of installation are you running?

Home Assistant OS

Integration causing the issue

RainMachine

Link to integration documentation on our website

https://www.home-assistant.io/integrations/rainmachine/

Diagnostics information

No response

Example YAML snippet

No response

Anything in the logs that might be useful for us?

2023-05-05 12:35:40.914 WARNING (MainThread) [homeassistant.config_entries] Config entry 'Rainmachine' for rainmachine integration not ready yet: Connection error while requesting data from https://10.0.0.217:443/api/4/auth/login; Retrying in background

Additional information

I tried removing the integration. rebooting the home assistant box, then re-adding it but I get an “Invalid authentication” error in the UI adding it the same way I used to (specifying the IP, the password, and using port 443 which is the https port). I’d love to just use port 80 instead with no https but this integration just flat out doesn’t support that so I was using port 443 previously which was working fine. Not sure what changed. Possibly something related to https cert verification.

See the discussion here for some background on the HTTPS cert verification stuff that I’m talking about: https://github.com/home-assistant/core/issues/80494

Per @bachya in that ticket: “Home Assistant will downgrade its TLS versions when connecting to a gen1 RainMachine.”

Not sure if maybe it’s just flat out failing to downgrade TLS version now and so the connection just doesn’t work via https anymore. That seems like a possibility. @bachya would probably be a good resource to look in to this.