derickr / activitypub

ActivityPub Library

The code in this repository can be used to run a light way activity pub server.

Set-Up

To use this, create a new directory for your project, and run the following steps:

composer require derickr/activitypub
mkdir data && chmod 0600 data && chown www-data:social-www-data data
mkdir html
mkdir scripts

The data directory needs to be able to be written to by your webserver's Unix user (for example www-data). Other files will also need to be written to by the Unix user running scripts to create new users.

I have set up the additional group to include both myself (derick) and the web server Unix user (www-data) under the group social-www-data:

social-www-data:x:1015:derick,www-data

In the html directory, create an index.php file with the following content:

<?php
require '../vendor/autoload.php';

use \DerickR\ActivityPub\Instance;
use \DerickR\ActivityPub\Storage\OnDisk;

/* Optional for debugging */
ini_set('error_log', '/tmp/php-errors.log');
ini_set('log_errors', true);

$instance = $_SERVER['HTTP_HOST'];
$i = new Instance( $instance, new OnDisk( __DIR__ . '/../data' ) );
$i->setDebug( true );
$i->run();

if ( preg_match( '#^/images/(.*)\.jpg$#', $_SERVER['REQUEST_URI'], $matches ) )
{
    header('Content-Type: image/jpeg');

    echo file_get_contents( __DIR__ . "/images/{$matches[1]}.jpg" );
    exit();
}

You can then set-up your web server to route all files through index.php. My lighttpd configuration section looks like:

$HTTP["host"] =~ "^.*social\.example\.com$" {
    url.rewrite-once = (
        "^/.*?(\?.*)?$" => "/index.php$1"
        )

    accesslog.filename = "|/usr/bin/cronolog /var/log/lighttpd/social.example.com/%Y/%m-%d-access.log"
}

Creating New Users

You can create a new user with the following script (stored in the scripts directory):

<?php
require '../vendor/autoload.php';

use \DerickR\ActivityPub\Storage\OnDisk;

if ($argc < 3) {
        echo "Usage: php new-user.php <username> <displayName>\n\n";
        die();
}

/** Configuration */
$account = trim($argv[1]);
$displayName = trim($argv[2]);

/** INI Settings */
ini_set('error_log', '/tmp/php-errors.log');
ini_set('log_errors', true);

$provider = new OnDisk(__DIR__ . '/../data');
$provider->createUser($account, $displayName);

You might have to change the require line, depending on where you store your script.

Posting a Simple Status

To post a simple text status, I used the following code:

<?php
require '../vendor/autoload.php';

use \DerickR\ActivityPub\DataTypes\Note;
use \DerickR\ActivityPub\DataTypes\Tag;
use \DerickR\ActivityPub\Instance;
use \DerickR\ActivityPub\Storage\OnDisk;

if ($argc < 3) {
                echo "Usage: php text-post.php <username> <text>\n\n";
                die();
}

/** Configuration */
$instanceUri = 'social.derickrethans.nl';
$account = trim($argv[1]);
$text = trim($argv[2]);

/** INI Settings */
ini_set('error_log', '/tmp/php-errors.log');
ini_set('log_errors', true);

$provider = new OnDisk( __DIR__ . '/../data');
$instance = new Instance($instanceUri, $provider);
$instance->setDebug(true);

$post = new Note("https://{$instance->getHostName()}/@{$account}", $text);
$post->addTag(new Tag("HashTag", "#ActivityPub"));

$message = $instance->newCreateMessage($account, $post);
$message->addCC("https://{$instance->getHostName()}/@{$account}/followers");

$instance->processMessage($message);

Posting a Complex Status

To post something more complex, I use the following script:

<?php
require '../vendor/autoload.php';

use \DerickR\ActivityPub\DataTypes\Create;
use \DerickR\ActivityPub\DataTypes\Note;
use \DerickR\ActivityPub\Instance;
use \DerickR\ActivityPub\Storage\OnDisk;

if ($argc < 3) {
        echo "Usage: php post.php <username> <url>\n\n";
        die();
}

/** Configuration */
$instance = 'social.derickrethans.nl';
$account = trim($argv[1]);
$url = trim($argv[2]);

/** INI Settings */
ini_set('error_log', '/tmp/php-errors.log');
ini_set('log_errors', true);

$provider = new OnDisk( __DIR__ . '/../data');
$instance = new Instance($instance, $provider);
$instance->setDebug(true);

$messageJson = file_get_contents($url);
$post = Note::fromJsonString($messageJson);

$message = $instance->newCreateMessage($account, $post);
$message->addCC("https://{$instance->getHostName()}/@{$account}/followers");

$instance->processMessage($message);

This reads the URL (or File) given by the second argument to use as post data.

This is a JSON file, which needs to have the contents like below. Make sure to replace user by the name of the actual user, as given as first argument to your script invocation:

{
        "@context": [
                "https:\/\/www.w3.org\/ns\/activitystreams",
                {
                        "Hashtag": "https:\/\/www.w3.org\/ns\/activitystreams#Hashtag"
                }
        ],
        "id": "https:\/\/social.example.com\/@user\/posts\/unique-post-filename.json",
        "type": "Note",
        "published": "2024-03-01T18:30:00+00:00",
        "attributedTo": "https:\/\/social.example.org\/@user",
        "content": "",
        "to": [
                "https:\/\/www.w3.org\/ns\/activitystreams#Public"
        ],
        "location": {
                "name": "Tasty Restaurant, London S1A 5ET, UK",
                "type": "Place"
        },
        "tag": [
                {
                        "type": "Hashtag",
                        "name": "#YourHashTag"
                }
        ],
        "attachment": [
                {
                        "type": "Image",
                        "mediaType": "image\/jpeg",
                        "url": "https:\/\/derickrethans-blog-photos.s3.eu-west-2.amazonaws.com\/friday-night-dinners\/nazuki-garden-1.jpg",
                        "name": "Image Description"
                }
        ]
}

The location, tag, and attachment fields are all optional. Location is modelled after https://www.w3.org/TR/activitystreams-vocabulary/#places; tags after https://www.w3.org/TR/activitystreams-vocabulary/#microsyntaxes (array form only); and attachments on https://docs.joinmastodon.org/entities/MediaAttachment/

I'm not 100% sure where this all comes from, but it works from my experiments. Mastodon doesn't show location yet though.