Fedi Groups

How it works

This is an approximation of groups you can use right now with existing fedi software that implements the Mastodon client API.

A group is a regular user account controlled by a "bot" service that runs on a Linux server (e.g. a Rpi in your closet). To join a group, simply follow the group user. To post into the group, tag the group user in a top-level post (not a reply), or use /b in a reply to share the parent post to the group. The group will reblog shared posts to its members.

Groups implement moderation (banning users and instances, member-only mode with user whitelist). This is controlled by slash commands, see below.

Group admins can issue group announcements that are posted poublicly by the group user, such as when there is a planned maintenance. The group will attempt to catch up with posts missed during the outage.

Note: In this document, "reblog" and "boost" are used interchangeably.

Advantages of emulated groups

Unlike some other attempts at group implementation (namely gup.pe or the mythical WIP Pleroma Groups), this works with current Pleroma and Mastodon. There's no need for interoperability in different server implementations, since it uses existing follow/mention/reblog features that are already cross-compatible. Mastodon users can join a group running on Pleroma and vice-versa.

Groups probably can't be hosted on Honk and Misskey, but their users can use groups hosted elsewhere just fine.

Setup

Building

Install the rust toolchain using rustup: https://www.rust-lang.org/tools/install

Rust 1.54+ is recommended.

Build with cargo build, or optimized: cargo build --release. The binary is placed in the target/debug or target/release directory.

You can also run the program using Cargo, that is handy for development: cargo run. When passing command line flags, use --: cargo run -- -i my@group.xyz.

Setting up a group account

1. Create the group's account all nice like you want it. Pleroma and Mastodon should work, others may work too but you're on your own.
2. Run the group service with fedigroups -a mygroup@groups.social (your account's handle) to authenticate.
3. Make sure you auth as the correct user!
4. Paste the Oauth2 token you got into the terminal, hit enter.

The program now ends. The credentials are saved in the directory groups.d/account@server/, which is created if missing.

You can repeat this for any number of groups.

In case you need to re-authenticate an existing group, do the same but use -A instead of -a.

Editing config

Do not edit the config while the group service is running, it may overwrite your changes!

Each group is stored as a sub-directory in groups.d. The sub-directories are normally named after their accounts, but this is not required.

The group's config and state is split into three files:

• config.json - immutable config, never changed beside when you run the -A command to reauth the group. This is where the auth token and the enabled flag are stored.
• control.json - settings and state that changes at runtime or can be set using slash commands. This file is overwritten by the group service when needed.
• state.json - frequently changing state data. The last-seen status/notification timestamps are kept here. State is split from Control to reduce the risk of damaging the control file. Timestamps can be updated multiple times per minute.

The JSON files are easily editable, you can e.g. add yourself as an admin (use the e-mail format, e.g. piggo@piggo.space).

When adding hashtags, note that they must be entered as lowercase!

The file format is quite self-explanatory.

config.json

{
  "enabled": true,
  "acct": "group@myserver.xyz",
  "appdata": {
    "base": "https://myserver.xyz",
    "client_id": "...",
    "client_secret": "...",
    "redirect": "urn:ietf:wg:oauth:2.0:oob",
    "token": "..."
  }
}

control.json

{
  "group_tags": [
    "grouptest"
  ],
  "admin_users": [
    "admin@myserver.xyz"
  ],
  "member_only": false,
  "member_users": [],
  "banned_users": [],
  "banned_servers": [
    "bad-stuff-here.cc"
  ]
}

• group_tags - group hashtags (without the #), lowercase! The group reblogs anything with these hashtags if the author is a member.
• member_users - group members, used to track whose hashtags should be reblogged; in member-only groups, this is also a user whitelist.
• banned_users - can't post or interact with the group service
• banned_servers - work like an instance block

state.json

{
  "last_notif_ts": 1630011219000,
  "last_status_ts": 1630011362000
}

Running

To run the group service, simply run it with no arguments. It will find groups in groups.d and start the service threads for you.

Note that the control and status files must be writable, they are updated at run-time. Config files can have restricted permissions to avoid accidental overwrite.

An example systemd service file is included in the repository as well. Make sure to set up the system user/group and file permissions according to your needs. You can use targets in the included Makefile to manage the systemd service and look at logs.

Group usage

Sharing into the group

The group will boost any status meeting these criteria:

• The visiblity is public or unlisted
• It's not a command request (i.e. mentions the group user and contains valid command(s))
• Either:
  • it mentions the group user and is not a reply
  • or, it contains one of the group hashtags

Examples of posts that will be shared:

• @group Look at this duck (public or unlisted)
• Look at this duck @group (public or unlisted)
• I love #ducks (public or unlisted, if #ducks is a group hashtag)
• @otheruser tell me about #ducks (in a thread, public or unlisted, if #ducks is a group hashtag)
• Ducks are cool @otheruser @group (original post)

These won't be shared:

• ducks suck
• @group #ducks /i (anything with the "ignore" command is ignored)
• @group /remove #ducks (admin command, even if it includes a group hashtag)
• @otheruser tell me about #ducks (in a thread)
• @otheruser @group tell me about ducks (in a thread)

Commands

Commands are simple text lines you use when mentioning the group user. DMs work well for this. One post can contain multiple commands; the replies will be batched to one response.

Replies keep the same visibility level as the post with the command.

Posts with commands, mentioning the group, won’t be boosted.

Membership

When a user follows a group, the group follows them back and marks them internally as a member. (In member-only groups, a group admin must initiate the second part).

Admin can add or remove group members using the /add and /remove commands. Users can use /join and /leave.

Members can use /join to make the group re-follow them, for example when the follow somehow stopped working.

Group mentions

Any user (member in member-only groups) can post to the group by mentioning the group user. The post is then reblogged.

Group hashtags

Admins can add hashtags to the group config (/add #hashtag, remove the same way: /remove #hashtag). Hashtags are case-insensitive.

When a group member posts one of the group hashtags, the group will reblog it. This is a nicer way to share posts, you don't have to mention the group user at all.

For group hashtags to work, the group user must follow all its members; otherwise the posts might not federate to the group's server.

Opting-out and #nobot

The group service respects the #nobot tag in users' profiles. When it's detected, the user's posts can't be shared to the group using the /boost command, unless they explicitly join.

To prevent individual groups from boosting your posts, use the /optout command.

List of commands

Note on command arguments:

• When a command wants user handle as an argument, use the e-mail form, e.g. piggo@piggo.space, to avoid mentioning the user.
• Local users can be specified without the domain part, but the first @ is then needed.
• When specifying a server (for server ban commands), the name must contain at least one dot.
• Hashtags are specified in their full form with a hash.

Basic commands

• /help - show help
• /ignore (alias /i) - make the group completely ignore the post
• /members (alias /who) - show group members / admins
• /tags - show group hashtags
• /boost (alias /b) - boost the replied-to post into the group
• /ping - ping the group service to check it's running, it will reply
• /join - join the group
• /leave - leave the group
• /optout - forbid sharing of your posts to the group (no effect for admins and members)
• /optin - reverse an opt-out
• /undo - undo a boost of your post into the group, e.g. when you triggered it unintentionally. Use in a reply to the boosted post, tagging the group user. You can also un-boost your status when someone else shared it into the group using /boost, this works even if you're not a member.

For admins

• /announce x - make a public announcement from the rest of the status. Note: this does not preserve any formatting!
• /ban user@domain - ban a user from interacting with the group or having their statuses shared
• /unban user@domain - lift a user ban
• /ban domain.tld - ban a server (works similar to instance mute)
• /unban domain.tld - lift a server ban
• /op user@domain (alias /admin) - grant admin rights to a user
• /deop user@domain (alias /deadmin) - revoke admin rights
• /closegroup - make the group member-only
• /opengroup - make the group public-access
• /add user@domain (alias /follow) - add a member
• /remove user@domain (alias /remove) - remove a member
• /add #hashtag (alias /follow) - add a hashtag to the group
• /remove #hashtag (alias /unfollow) - remove a hashtag from the group
• /undo (alias /delete) - when used by an admin, this command can un-boost any status. It can also delete an announcement made in error.