Comment embeds: track embed views without PII

Use the anonymous event tracker on embed views to prevent sending
any personally identifiable information.

r2/example.ini

@@ -122,6 +122,7 @@ clicktracker_url = /click
 uitracker_url = /pixel/of_discovery.png
 # embeds pixel tracking url
 eventtracker_url = /pixel/of_delight.png
+anon_eventtracker_url = /pixel/of_diversity.png
 # google analytics token
 googleanalytics =
 # google analytics events sampling rate. Valid values are 1-100.

r2/r2/lib/embeds.py

@@ -82,6 +82,7 @@ def set_up_embed(embed_key, sr, thing, showedits):
 
     c.embed_config = {
         "eventtracker_url": g.eventtracker_url or "",
+        "anon_eventtracker_url": g.anon_eventtracker_url or "",
         "created": iso_timestamp,
         "showedits": showedits,
         "thing": {

r2/r2/lib/template_helpers.py

@@ -174,6 +174,7 @@ def js_config(extra_config=None):
         "clicktracker_url": g.clicktracker_url,
         "uitracker_url": g.uitracker_url,
         "eventtracker_url": g.eventtracker_url,
+        "anon_eventtracker_url": g.anon_eventtracker_url,
         "comment_embed_scripts": js.src("comment-embed", absolute=True, mangle_name=False),
         "static_root": static(''),
         "over_18": bool(c.over18),

r2/r2/public/static/js/embed/embed.js

@@ -62,9 +62,10 @@
 
     var tracker = new App.PixelTracker({
       url: config.eventtracker_url,
+      anonymousUrl: config.anon_eventtracker_url,
     });
 
-    tracker.send(createPayload(type, 'view'));
+    tracker.send(createPayload(type, 'view'), {anonymous: true});
   
     function trackLink(e) {
       var el = this;

r2/r2/public/static/js/embed/pixel-tracking.js

@@ -2,12 +2,23 @@
 
   var PixelTracker = App.PixelTracker = function(options) {
     this._pixelTrackingUrl = options.url;
+    this._anonymousPixelTrackingUrl = options.anonymousUrl;
   };
 
-  PixelTracker.prototype.send = function(payload, callback) {
+  PixelTracker.prototype.send = function(payload, options, callback) {
+    // Overload #send(payload, callback)
+    if (typeof options === 'function') {
+      callback = options;
+      options = {};
+    }
+
+    options = options || {};
     callback = callback || function() {};
 
-    if (!this._pixelTrackingUrl || !payload) {
+    var url = options.anonymous ?
+      this._anonymousPixelTrackingUrl : this._pixelTrackingUrl;
+
+    if (!payload || !url) {
       callback();
 
       return;
@@ -19,7 +30,7 @@
     var buster = Math.round(Math.random() * 2147483647);
 
     image.onload = callback;
-    image.src = this._pixelTrackingUrl +
+    image.src = url +
                 '?r=' + buster +
                 '&data=' + encodeURIComponent(JSON.stringify(payload));
   };