Webfinger

This service implements the WebFinger protocol, which allows remote services to discover local users.

Features#

Automatically find ActivityPub actors through their username
Returns a 404 error if the actor doesn't exist

Dependencies#

ApiGateway
ActivityPub ActorService

Install#

$ npm install @semapps/webfinger --save

Usage#

const { WebfingerService } = require('@semapps/webfinger');

module.exports = {
  mixins: [WebfingerService],
  settings: {
    baseUrl: "https://mydomain.com",
    domainName: "mydomain.com" // Not necessary if it is the same as usersContainer
  }
}

Settings#

Property	Type	Default	Description
`baseUrl`	`String`		Base URL of the server. Used to find the domain name if it is not set.
`domainName`	`String`		Domain name used for the user@domain webfinger identifier. If not set, the domain name will be guessed from the users' container.

Discovering an user with Webfinger#

In the Webfinger protocol, users are identified by their username and the domain name where they are hosted: username@domain. This is similar to email addresses, except services like Mastodon add a @ at the beginning.

To find an user, a simple GET is enough:

GET /.well-known/webfinger?resource=acct:simon@localhost HTTP/1.1
Host: localhost:3000
Accept: application/json

If the user exists locally, it will return a JSON like this:

{
  "subject": "acct:simon@localhost",
  "aliases": [
    "http://localhost:3000/actors/simon"
  ],
  "links": [
    {
      "rel": "self",
      "type": "application/activity+json",
      "href": "http://localhost:3000/actors/simon"
    }
  ]
}