this post was submitted on 21 Jun 2023
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homeassistant

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Home Assistant is open source home automation that puts local control and privacy first. Powered by a worldwide community of tinkerers and DIY enthusiasts. Perfect to run on a Raspberry Pi or a local server. Available for free at home-assistant.io

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Disclaimer: I haven’t done a lot of research yet. Still in the “how to handle this” stage.

My profile: Senior Full Stack Web App - with own infrastructure in the cloud, unraid locally. HASSOS in a vm.

Q: in September I’m getting solar panels. My parents lended me the money on the condition they can use up the extra energy I set the net. We live in Belgium and that is possible but to do so they have to take it at most 15 minutes after. For normal usage this is fine but I’m talking heat pump and machines and such.

Both houses have a home assistant setup. His is even more automated than mine. Both run on on a decent machine. Both have stable internet (UniFi) and he is paying for home assistant cloud. Atm I am not.

Now I do have a digital meter and just integrated that with my instance. First I made my own cable but then I stumbled upon “slimmelezer+” module and that thing is just fantastic!

Anyway now I have access to real time data. What would you do to get it to the other instance? I do not have a lot of time but I am experienced with webservices and have the servers. This would be read only off course! lol but I was wondering if any of you knew a project or has done this him/herself.

I’m thinking the easiest way would be for me to pay for cloud access and then create a user for them. They can then add my home to their apps. But it would be super duper sweet to fully integrate both houses!

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[–] [email protected] 2 points 1 year ago (4 children)

I'm assuming they aren't close enough to just run some cat6 between both houses and have a single instance govern them?

I'll be honest though, although your plan sounds cool as fuck, it also sounds like a really terrifying project from a security perspective.

[–] Gompje 1 points 1 year ago (2 children)

Nope. 2.5km or so but in a dense populated city 😁

I’m interested in your terrifying view though. Maybe I’m missing something, this is roughly what’s in my head now: (1 is my home, 2 is a a cloud server, 3 is my parents)

  • 1: pushes the relevant entities to 2. Read only.
  • 2 received the data. Validation here is a token system with permissions. I’m going to use my SaaS to do this given it already has this in place
  • 2 is storing the values in a database
  • 3 gets notified of the new values with web hooks. Again by 2, something I have yet to build in de SaaS but will be needed anyway
  • 2 can sanitize the values when needed. It will absolutely do validation and verification and such
  • 2 is very secure and is the only one who will do write, only to his own db
  • I’m not sure if 3 would be able to react to entities directly on 2 but I will investigate this. If not I can push the values
  • we make a read only graph on 3 that just displays the values.
  • I’m now thinking that doesn’t even have to be on 3 yet, I can just make a very secure view for them in the SaaS. With login and things, something that I already have. I can use an iFrame to let them view it in a dashboard of HA
  • later we could do automations when needed but that is not that urgent given I work from home and my parents are retired.

For me this seems very secure, more so given we mostly have read only things. maybe there is something I’m missing?

Sidenote: we have Smappee as well and can access each others home through their app. We can use this at first but it would just be cool to make this flow. I for one don’t want to be this dependent of some vendor, if you know what I mean..

[–] Gompje 1 points 1 year ago

Forgot to mention: 2 can even just send a notification to Slack to my parents. We are already using this. They are helping with testing the SaaS

[–] [email protected] 1 points 1 year ago

I’m interested in your terrifying view though.

I mean, don't misconstrue, I am exaggerating a bit and tend towards caution over utility in these matters - it's totally doable, of course :)

It's the overall intent that would worry me - as someone else said downthread, I'm not sure I see the necessity of having the two homes directly linked, and as we know, adding an unnecessary component to a system is necessarily increasing its threat surface. The involvement of a cloud service bothers me a bit - it'd be one thing to have three servers involved, all fully under your control, but what happens if your cloud provider has some kind of security disaster? How do you deal with an external adversary that then has access to both your and your parents' houses? Or worse, what happens when your parents decide to get experimental with HA and brick all your lights? (I kid - you do make it sound like your folks are switched on and technically sane, but in principle - shit can go wrong on their end).

Personally, I think I'd go very barebones and just host a single bit in a text file on a web server somewhere - your HA could flip it to 1 when there's power to buy, and your parents' HA can just poll that every 15 minutes and do whatever it needs to while the value stays at 1. No direct linkage, minimal threat surface, and any bad actor snooping around will only find out that some URL on some web server sometimes serves a '0' and sometimes serves a '1'.

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