Add node info endpoint

app/controllers/well_known/node_info_controller.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module WellKnown
+  class NodeInfoController < ActionController::Base
+    include RoutingHelper
+
+    before_action { response.headers['Vary'] = 'Accept' }
+
+    def index
+      render json: ActiveModelSerializers::SerializableResource.new({}, serializer: NodeDiscoverySerializer)
+    end
+
+    def show
+      render json: ActiveModelSerializers::SerializableResource.new({}, serializer: NodeInfoSerializer)
+    end
+  end
+end

app/presenters/instance_presenter.rb

@@ -14,6 +14,10 @@ class InstancePresenter
     to: Setting
   )
 
+  def active_count(timespan: Time.zone.now - 1.month..Time.zone.now)
+    Status.select('distinct (account_id)').where(local: true, created_at: timespan).count
+  end
+
   def contact_account
     Account.find_local(Setting.site_contact_username.gsub(/\A@/, ''))
   end

app/serializers/node_discovery_serializer.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+class NodeDiscoverySerializer < ActiveModel::Serializer
+  include RoutingHelper
+
+  attributes :links
+
+  def links
+    [
+      {
+        rel: 'http://nodeinfo.diaspora.software/ns/schema/2.0',
+        href: node_info_schema_url('2.0'),
+      },
+    ]
+  end
+end

app/serializers/node_info_serializer.rb

@@ -0,0 +1,84 @@
+# frozen_string_literal: true
+
+class NodeInfoSerializer < ActiveModel::Serializer
+  include RoutingHelper
+
+  attributes :version, :usage, :software, :services,
+             :protocols, :openRegistrations, :metaData
+
+  def version
+    '2.0'
+  end
+
+  def usage
+    {
+      users: {
+        total: instance_presenter.user_count,
+        activeHalfyear: instance_presenter.active_count(timespan: Time.zone.now - 6.months..Time.zone.now),
+        activeMonth: instance_presenter.active_count,
+      },
+      localPosts: instance_presenter.status_count,
+    }
+  end
+
+  def software
+    {
+      version: Mastodon::Version.to_s,
+      name: 'mastodon',
+      repository: Mastodon::Version.source_base_url,
+    }
+  end
+
+  def services
+    {
+      outbound: [],
+      inbound: [],
+    }
+  end
+
+  def protocols
+    %w(ostatus activitypub)
+  end
+
+  def openRegistrations
+    Setting.open_registrations
+  end
+
+  def metaData
+    {
+      nodeName: instance_presenter.site_title,
+      nodeDescription: instance_presenter.site_description,
+      nodeTerms: instance_presenter.site_terms,
+      siteContactEmail: instance_presenter.site_contact_email,
+      domain_count: instance_presenter.domain_count,
+      features: features,
+      invitesEnabled: Setting.min_invite_role != 'admin',
+      federation: federation,
+    }
+  end
+
+  def features
+    %w(mastodon_api mastodon_api_streaming)
+  end
+
+  def federation
+    domains = DomainBlock.all
+    feds = {
+      reject_media: [],
+      reject_reports: [],
+    }
+    domains.each do |domain|
+      feds[domain.severity] = [] unless feds.keys.include?(domain.severity)
+      feds[domain.severity] << domain.domain
+      feds[:reject_media] << domain.domain if domain.reject_media
+      feds[:reject_reports] << domain.domain if domain.reject_reports
+    end
+    feds
+  end
+
+  private
+
+  def instance_presenter
+    @instance_presenter ||= InstancePresenter.new
+  end
+end

config/routes.rb

@@ -19,7 +19,9 @@
                 tokens: 'oauth/tokens'
   end
 
-  get '.well-known/host-meta', to: 'well_known/host_meta#show', as: :host_meta, defaults: { format: 'xml' }
+  get '.well-known/host-meta', to: 'well_known/host_meta#show', as: :host_meta,    defaults: { format: 'xml' }
+  get '.well-known/nodeinfo', to: 'well_known/node_info#index', as: :node_info,    defaults: { format: 'json' }
+  get 'nodeinfo/:version_number', to: 'well_known/node_info#show',  as: :node_info_schema, defaults: { format: 'json' }
   get '.well-known/webfinger', to: 'well_known/webfinger#show', as: :webfinger
   get '.well-known/change-password', to: redirect('/auth/edit')
   get 'manifest', to: 'manifests#show', defaults: { format: 'json' }

spec/controllers/well_known/node_info_controller_spec.rb

@@ -0,0 +1,38 @@
+require 'rails_helper'
+
+describe WellKnown::NodeInfoController, type: :controller do
+  render_views
+
+  describe 'GET #index' do
+    it 'returns json document pointing to node info' do
+      get :index
+
+      json_response = JSON.parse(response.body)
+
+      expect(response).to have_http_status(200)
+      expect(response.content_type).to eq 'application/json'
+      expect(json_response.keys.include?('links')).to be true
+      expect(json_response['links'][0]['rel']).to eq 'http://nodeinfo.diaspora.software/ns/schema/2.0'
+      expect(json_response['links'][0]['href'].include?('nodeinfo/2.0')).to be true
+    end
+  end
+
+  describe 'GET #show' do
+    it 'returns json document pointing to node info' do
+      get :show, params: { version_number: 2 }
+
+      json_response = JSON.parse(response.body)
+
+      expect(response).to have_http_status(200)
+      expect(response.content_type).to eq 'application/json'
+      expect(json_response.keys.include?('version')).to be true
+      expect(json_response.keys.include?('usage')).to be true
+      expect(json_response.keys.include?('software')).to be true
+      expect(json_response.keys.include?('services')).to be true
+      expect(json_response.keys.include?('protocols')).to be true
+      expect(json_response.keys.include?('openRegistrations')).to be true
+      expect(json_response.keys.include?('usage')).to be true
+      expect(json_response.keys.include?('metaData')).to be true
+    end
+  end
+end