Technically? Yes you can. Will it be a good experience? I truly doubt it.
You must have a Domain Name, you can do this for free with services like No-IP, with Dynamic DNS you can keep the Domain updated and pointing to your Raspberry Pi.
Now, you will find some issues, that I think are really important and I don’t really think you have a very great developer profile.
- Build a custom docker image from Discourse’s one to support ARM (Docker’s abstraction might help a little), but at this point maybe getting a VM on top of the Raspberry would be easier (adding ton of overhead)
- Handling the extremely low performance of ARM cores, I don’t know how good is Discourse handling load between cores (other than building).
- Handling Discourse with only 1GB of RAM, when it recommends at least 2GB.
- As said by @Stephen really, but really slow performance by the SD cards, and you’ll hit that SD A LOT because if using 2GB of RAM you hit SWAP, with only 1GB, most of your forum will be running in the SD.
Is it a good idea to run Discourse that way? Maybe for testing or as a project, just to prove it can be done.
For a production instance? No way it’s a good idea. You can get Discourse running with as little as 5$/month with Digital Ocean, 2-4$ if you search for cheaper options as Vultr, OVH, etc. And ~12$/year for a domain.
We’re talking less than 10$ per month hosting it online, I think that’s even cheaper than running Discourse 24/7 on a PC.