Remote follow

[SleeplessOne1917]

Description

Taking @Nutomic's suggestion from #1804 to make a flow for federating with communities from remote instances. So far I've only made a modal for it. I could add a route to the UI to handle these redirects, but what about Mastodon, Pleroma, Calckey, etc? Is there any standard path to target for this sort of thing?

Screenshots

Remote Fetch Page

Success

Loading

Failed

[wiki-me]

It's a nice feature, but TBH most users will probably be served better by some browser extension that sets their "home instance" (lemmy tools?), maybe suggesting that also can make people think lemmy can be less of a hassle?

[Madis0]

How about showing all three options in the modal and therefore removing the blue info box from the right?

• Log in to subscribe on instance.example
• Enter instance to subscribe on it: ________
• Search !community@instance.example on your instance to subscribe

[Nutomic]

Based on this comment the path is available via webfinger. So it will also require some backend changes.

[dessalines]

That means we will need to add a front end route for this:

https://MY_INSTANCE/activitypub/externalInteraction?uri={uri}

[SleeplessOne1917]

@Nutomic @dessalines @jsit @alectrocute I updated this to have a page to redirect to. I could use some eyes on this.

[dessalines]

The components and everything seem to work okay, but I'm struggling coming up with a way we can actually test this, besides putting it on our federation test instances.

[poVoq]

No, that is exactly what I understood and I still think the name part is unnecessary and confusing.

For the redirect to your home server to work, you need to be logged in, thus your home community already knows your account name.

[SleeplessOne1917]

The way the flow is currently implemented in this PR is closer to what @poVoq describes than the flow laid out in @Nutomic's comment. The way it works right now is:

1. User has an account on lemmy.ml
2. User browses sopuli.xyz and finds an interesting community
3. User clicks on "remote follow" button, enters domain lemmy.ml and submits.
4. If user is logged in they go directly to step 5. If not, they are brought to the login page and redirected after logging in.
5. User is sent to https://lemmy.ml/activitypub/externalInteraction?uri=https://sopuli.xyz/c/interestingCommunity (community uri not encoded here for readability)
6. resolveObject request is made with user's auth and a query in the form of !interestingCommunity@sopuli.xyz.
7. Based on the resolveObject response:
   • Success: display the community's info in a card with a button for the user to subscribe.
   • Loading: Loading spinner
   • Failure: Failure screen displayed

[Nutomic]

User is sent to https://lemmy.ml/activitypub/externalInteraction?uri=https://sopuli.xyz/c/interestingCommunity (community uri not encoded here for readability)

This is going to break if the user is on another platform. There it needs to go to https://mastodon.social/authorize_interaction?uri={uri}". Thats why the webfinger query is necessary, and for that we need the username.

[poVoq]

Mastodon does not require this, see:

And I have used this exact form with just a instance domain redirecting to Hubzilla before and it worked fine. However I just tried it with Akkoma and it doesn't seem to work there (with the full name it does though).

[SleeplessOne1917]

I'm struggling to figure out what the right way forward on this is given the lack of consensus. @Nutomic @poVoq @dessalines

[dessalines]

@Nutomic is any of this PR necessary then? LemmyNet/lemmy#3738

If not, I'd say we should merge this, and use the federation test instances to debug / tweak it.

[Nutomic]

You can already test this with the setup in Lemmy repo docker/federation, by manually building a lemmy-ui image from this branch and putting that in the docker-compose file.

@poVoq I think that approach only works with platforms that use the same endpoint /authorize_interaction?uri={uri}. I tried with peertube just now and it gives an error 404 because it uses /remote-interaction?uri=. So the backend PR is necessary if we want to support different platforms such as Peertube.

[SleeplessOne1917]

I'm going to work on this again. @Nutomic I'm not sure what steps need to be taken to make this work with the backend change. What endpoint should I be hitting for this? It might make sense to add logic for this to the JS client as well.

[Nutomic]

The Lemmy backend tells other Fediverse software that remote follow is available at /activitypub/externalInteraction?uri={{uri}}. Where {{uri}} is the actor_id of a community which can be passed to /api/v3/site/resolve_object. So you need to add a handler in lemmy-ui for /activitypub/externalInteraction which resolves the given community, and then shows a dialog "Do you want to follow this community yes/no?"

[SleeplessOne1917]

@Nutomic the existing flow is already the same as what you described in your most recent comment. See this video:

remote_fetch_demo.mp4

The only rub is that even though the remote community is resolved, the subscribed state never stops being pending. I don't know if this is due to a flaw in how I implemented it or if it's a quirk of testing locally.

[Nutomic]

I tested it locally and can reproduce that problem. Its weird because the follow goes through if I fetch another community manually and press the sidebar subscribe button. Is there any difference between that and the new follow button you added for the remote follow dialog?

Im also getting various API error: unknown logged by lemmy-ui when viewing a remote community. Any idea what that is? Seems like the backend is returning 404 for some reason, would be good if lemmy-ui returned the actual backend error.

[SleeplessOne1917]

I just tested this with the existing way of fetching remote communities by using the search page and ran into the exact same problem. I think this might only be an issue with testing federation locally, as opposed to an issue caused by my changes.

[SleeplessOne1917]

I just added the remote follow logic to the subscribe buttons on the communities page too:

I'm unsure if I should keep the button look here or go back to making it look like a link like it was before.

[dessalines]

Not a huge fan of that button, for some reason they don't look great in tables. But I leave that up to you.

Once you fix the conflicts, feel free to merge. Then I'll make some RC's, because this is going to need some playing around with on the test instances for sure.