Greg Kennedy, 2023
Small, post-only ActivityPub implementation in PHP
This is a PHP-based project to allow a host to post messages into the Fediverse to subscribed Followers. It implements the minimum of the ActivityPub spec for server-to-server federation, specifically:
- a WebFinger response at /.well-known/webfinger to describe Actor inboxes and accounts
- an Inbox which receives (and approves) Follow and Undo-Follow requests
- a post.php webhook which accepts a post and broadcasts it to Followers' inboxes
These features together allow the host's accounts to be discoverable by other ActivityPub servers, and they may issue Follow requests which are automatically approved. When this host wants to make a post, a cURL call will then broadcast the message to all Followers who have opted in.
It is similar to express-activitypub by Darius Kazemi, except written in PHP instead of Node.js.
There is a basic human-readable Index page with information about the Actors located on the server. For managing Actors on this host, or manual posting, there is an admin page as well. Newly created actors receive a randomized API Key, which must be included in the header of subsequent calls to the post.php webhook.
Note that this extremely reduced spec is missing a lot of critical functionality one would expect in an ActivityPub service - for example, phpActivityPub does not accept posts from others. It is thus mostly useful as a tool for bots, relays (RSS / Twitter / etc), or other read-only broadcast applications.
- PHP
- php-sqlite3
- php-openssl
- php-curl
- Web server: I use Apache with
.htaccessrewrites, you will need alternate rules for other servers
Clone the repository into your web service HTML tree.
The admin/ folder is password-protected using HTTP Basic auth with a .htpasswd file. Use the htpasswd utility to create a username and password for logging in.
Log into the Admin page and click "create" to set up a new Actor. The server will provide a random string of characters for your Key, which must be present in an HTTP "X-API-KEY" header to post.
Posts should be JSON and will be added to the necessary Activity fields to build a complete post. Some examples of post body:
{ "content": "Hello, world!" }creates a Note (the default) with the text "Hello, world!"
{ "type": "Link", "url": "http://www.example.com" }{ "type": "Image", "url": "http://www.example.com/image.jpg" }etc.
See POSTING.md for a more detailed example.
This fork provides some additional functionality for bots. It additionally addresses a couple of minor issues relevant to my own installation, viz database creation, and an Apache re-write. For details of rewrite rules, have a look at Apache.md
Additonal features:
In admin/profile.php you can populate some of the information that will be displayed when people search for your actor.
Created by user.php, which displays a barebones profile, inlcuding list of followers. You can use the profile admin page to set the URL of this for each user you create. This solves the problem where, for example, a follower on a remote Mastodon instance can't see who's following your bot, because that's not stored locally. Mastodon displays the 'url' of the actor as link to the original profile.
The latest update to inbox.php detects when a DM is sent to one of your actors, and then hands the content off to a parse_content function in the include file dm_parser.php. This is intended to keep some site specific code separate from the rest of the functionality. The example included allows followers to request a summary of events in a particular city by sending a DM to our bot with the name of the city.