🆕 blog! “ActivityPub Server in a Single PHP File”
Any computer program can be designed to run from a single file if you architect it wrong enough! I wanted to create the simplest possible Fediverse server which can be used as an educational tool to show how ActivityPub / Mastodon works. The design goals were: Upload a single PHP file to the server. No […]
👀 Read more: https://shkspr.mobi/blog/2024/02/activitypub-server-in-a-single-file/
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#ActivityPub #mastodon #php
@Edent great stuff; I'd seen the previous Symfony-based iteration on Github, and my first thought was "I bet you can get that down to a simple single file install" 🙂
@Edent Nice work! It looks similar to my own self-study one-file ActivityPub server in Python. I think the structure of the protocols lends itself to implementing single-actor servers as a learning experience.
I know you're saying it's quick & dirty in some ways, but if it's intended as a learning tool for others, do you want feedback on it? There's one bad assumption in there that I think would be better if it was cleaned up.
@Edent Then I'll make it short: The assumption that a server has a shared inbox at /inbox does not generalize, as even the existence of a shared inbox is not mandated by anything.
What you'd need to do is when someone follows, you fetch their actor data and store at minimum their inbox and/or shared inbox.
For sending, I build a set of all shared inboxes that occur more than once, and use the individual inboxes for the rest.
@julian interesting! Thanks.
How difficult do you think that is to implement? I'm wary of making something too complicated - but I'd like to point to a simple solution if possible.
@Edent In my code I do the "fetch actor on follow and store inboxes" strategy I mentioned, and then at the point I want to send a post, I do this:
The code is a bit opaque. I keep a map of shared inboxes to individual inboxes that have already been added to the send list, and if a shared inbox appears a second time, I remove the previous individual inbox from the send list and add the shared inbox.
@Edent nice, I was thinking of writing a simple #activitypub server for a single account that would use an #rss xml file as a source. Pretty sure this has already been done anyway.
By popular demand, my demo ActivityPub server now also shows how to attach images to a Note.
View @example for an example.
Get the code at https://gitlab.com/edent/activitypub-single-php-file/
But the one thing I can't figure out…
When I mention "@ example @ example.viii.fi", it shows as:
Which links back to the user's website, rather than showing their info within Mastodon.
Which arcane #ActivityPub or #MastodonAPI field do I need to have in my JSON file to fix this?
@robb nice! Would you mind following (temporarily) and telling me if it backfills the previous posts?
@Edent followed but I can tell you now it won’t.
My instance doesn’t know about those previous posts, only ones that have been sent after I’ve followed.
@Edent It does fill in the post number and other info, but clicking on posts won’t show anything. For that, I need to visit the profile
@fallenhitokiri @example
Hmmm. It really should show an avatar image as well.
Something else to look into.
@Edent in the client I use (Megalodon), it opens correctly. However, I get what you're discribing with some posts from users of other fedi servers. I did not yet make the effort to find out which ones, though.
@pixelcode it's my website. I'm not sad about it at all.
It was the only way I could cut down on spam & abuse. My website is available on the open Internet.
@Edent I've often wondered how hard would it be to make a PHP port of Mastodon. Setting up the Ruby version can be a pain.
@Edent is there an article anywhere that shows / explains the full workflow that a mastodon server does?
@Edent @example check this out ... https://maho.dev/2024/02/a-guide-to-implementing-activitypub-in-a-static-site-or-any-website-part-3/
TLDR; Depends on who implements the actor, the uri/url field is used by mastodon as the profile one. Like @blog
I've now added HTTP Message Signature verification to my demo #ActivityPub server.
Currently the entire server is a 32KB single PHP file.
Feedback welcome! It is designed to be a learning tool to show how all the different parts of ActivityPub work.
OK! My tiny #ActivityPub server can now follow users from other instances!
Still under 40KB of well-documented PHP.
https://gitlab.com/edent/activitypub-single-php-file/
You can follow and message the test user a @example
@Edent I enjoyed the little jokes in the comments :)
Looks like you've got the hang of it. It's all just learning the quirks of different implementations, now!
@AlanBell If you refresh, it should show as approved.
I think it's because I have the profile saying it is manual - but it isn't.
@AlanBell I *think* it is because @masto_ie_support uses authorised fetch. So my server can't retrieve your public key without signing the request.
I'll see if I can adjust that on my side.
