Hybrid Content Telemetry

Hybrid content is web content that is loaded as part of Firefox, appears as part of Firefox to the user and is primarily intended to be used in Firefox. This can be either a page that ships with Firefox or that can be loaded dynamically from our hosted services. Hybrid content telemetry allows Mozilla pages to check whether data collection is enabled and to submit Telemetry data.

Important

Every new data collection in Firefox (including hybrid content) needs a data collection review from a data collection peer. Just set the feedback? flag for one of the data peers. They try to reply within a business day.

The recorded data will be sent to Mozilla servers by Firefox, if the collection is enabled, with the main-ping.

Adding content data collection

Telemetry can be sent from web content by:

  1. granting the web content’s host privileges in the Firefox codebase;
  2. including the HybridContentTelemetry-lib.js file in the page;
  3. registering the probes after the library is loaded;
  4. using the API to send Telemetry.

Granting the privileges

For security/privacy reasons Mozilla.ContentTelemetry will only work on a list of allowed secure origins. The list of allowed origins can be found in browser/app/permissions . A host needs to be given the hc_telemetry permission in order to be whitelisted.

Example:

origin  hc_telemetry  1 https://discovery.addons.mozilla.org

Adding an entry to the permissions file requires riding the trains. If “go-faster” content requires granting permissions to a Mozilla page, it can do so by using the permission manager

function addonInit() {
  // The following code must be called before attempting to load a page that uses
  // hybrid content telemetry on https://example.mozilla.org.
  let hostURI = Services.io.newURI("https://example.mozilla.org");
  Services.perms.add(hostURI, "hc_telemetry", Services.perms.ALLOW_ACTION);
}

function addonCleanup() {
  // The permission must be removed if no longer needed (e.g. the add-on is shut down).
  let hostURI = Services.io.newURI("https://example.mozilla.org");
  Services.perms.remove(hostURI, "hc_telemetry");
}

Important

Granted permissions do not disappear when a “go-faster” add-on is uninstalled but are cleared when the browser is closed. If permissions need to be cleaned without closing the browser, it must be done manually. Moreover, permissions are keyed by origin: http://mozilla.com and https://mozilla.com are different things.

Including the library

To use hybrid content telemetry the related content JS library needs to be included in the page. We have different integration options:

  • Add mozilla-hybrid-content-telemetry as a dependency to the project and require it in the code.
  • Load it directly from the external unpkg CDN.
  • Manually fetch the latest version from the main repository and add it to the page repository. Then this file can be deployed along with the page.

Example (manual inclusion):

<!DOCTYPE html>
<html>
  <head>
    <!-- Other head stuff -->
    <script type="application/javascript" src="HybridContentTelemetry-lib.js"></script>
  </head>
  <body> <!-- Other body stuff --> </body>
</html>

Example (NPM dependency):

Add the dependency to your project:

npm install --save mozilla-hybrid-content-telemetry@1.0.0

In your app load the module and use the API:

const ContentTelemetry = require("mozilla-hybrid-content-telemetry");

ContentTelemetry.registerEvents("page.interaction", {
  "click": {
    methods: ["click"],
    objects: ["red_button", "blue_button"],
  }
});

// Now events can be recorded.
ContentTelemetry.recordEvent("page.interaction", "click", "red_button");

Note

The following examples assume the manual inclusion of the JS library.

Registering the probes

Probe registration can happen at any time after the library is loaded in the page, but registering early enough ensures that the definition is available once a recording attempt is made.

Example:

<!DOCTYPE html>
<html>
  <head>
    <!-- Other head stuff -->
    <script type="application/javascript">
      window.onload = function() {
        if (!Mozilla || !Mozilla.ContentTelemetry) {
          // .. uh-oh, was library loaded? Report the error.
          return;
        }
        // Register the probe.
        Mozilla.ContentTelemetry.registerEvents("page.interaction", {
          "click": {
            methods: ["click"],
            objects: ["red_button", "blue_button"],
          }
        });
      };
    </script>
  </head>
  <body> <!-- Other body stuff --> </body>
</html>

Recording the data

Data recording can happen at any time after a probe has been registered. The data will be recorded and sent by Firefox if permitted by the Telemetry preferences.

Example:

<!DOCTYPE html>
<html>
  <head>
    <!-- Other head stuff -->
    <script type="application/javascript">
      function triggerEvent() {
        if (!Mozilla || !Mozilla.ContentTelemetry) {
          // .. uh-oh, was library loaded? Report the error.
          return;
        }
        Mozilla.ContentTelemetry.recordEvent("page.interaction", "click", "red_button");
      };
    </script>
  </head>
  <body>
    <!-- Other body stuff -->
    <div id="content">
      <button id='event-recording' onclick="triggerEvent();">
        Trigger Recording
      </button>
    </div>
  </body>
</html>

Checking if upload is enabled

Mozilla pages can check if data upload is enabled, as reported by Telemetry preferences. This is useful for pages which are not using Telemetry to collect data, but need to comply to our data policy for the collection.

Example:

<!DOCTYPE html>
<html>
  <head>
    <!-- Other head stuff -->
    <script type="application/javascript">
      function recordData() {
        if (!Mozilla || !Mozilla.ContentTelemetry) {
          // .. uh-oh, was library loaded? Report the error.
          return;
        }

        if (!Mozilla.ContentTelemetry.canUpload()) {
          // User has opted-out of Telemetry. No collection must take place.
          return;
        }

        // ... perform the collection without Telemetry below this point.
      };
    </script>
  </head>
  <body>
    <!-- Other body stuff -->
    <div id="content">
      <button id='event-recording' onclick="recordData();">
        Trigger Recording
      </button>
    </div>
  </body>
</html>

The API

The hybrid content API is available to the web content through the inclusion of the HybridContentTelemetry-lib.js library.

The initial implementation of the API allows the registration and the recording of events.

JS API

Authorized content can use the following functions:

Mozilla.ContentTelemetry.canUpload();
Mozilla.ContentTelemetry.initPromise();
Mozilla.ContentTelemetry.registerEvents(category, eventData);
Mozilla.ContentTelemetry.recordEvent(category, method, object, value, extra);

These functions will not throw. If an unsupported operation is performed (e.g. recording an unknown event) an error will be logged to the browser console.

Note

Data collected using this API will always respect the user Telemetry preferences: if a user has chosen to not send Telemetry data to Mozilla servers, Telemetry from hybrid content pages will not be sent either. Like other Telemetry data, it will still be recorded locally and available through about:telemetry.

Mozilla.ContentTelemetry.canUpload()

Mozilla.ContentTelemetry.canUpload();

This function returns true if the browser is allowed to send collected data to Mozilla servers (i.e. datareporting.healthreport.uploadEnabled is true), false otherwise. See preferences.

Note

The page should use this function to check if it is allowed to collect data. This is only needed in case the Telemetry system is not be being used for collection. If Telemetry is used, then this is taken care of internally by the Telemetry API. The page should not cache the returned value: users can opt in or out from the Data Collection at any time and so the returned value may change.

Example:

if (Mozilla.ContentTelemetry.canUpload()) {
  // ... perform the data collection here using another measurement system.
}

Mozilla.ContentTelemetry.initPromise()

Mozilla.ContentTelemetry.initPromise();

This function returns a Promise that gets resolved as soon as Hybrid Content Telemetry is correctly initialized and the value from canUpload can be reliably read. The promise will reject if Hybrid Content Telemetry is disabled or the host doesn’t have enough privileges to use the API.

Mozilla.ContentTelemetry.registerEvents()

Mozilla.ContentTelemetry.registerEvents(category, eventData);

Register new dynamic events from the content. This accepts the same parameters and is subject to the same limitation as Services.telemetry.registerEvents(). See the events documentation for the definitive reference.

Note

Make sure to call this before recording events, as soon as the library is loaded (e.g. window load event). This will make sure that the definition will be ready when recording.

The data recorded into events registered with this function will end up in the dynamic process section of the main ping.

Example:

Mozilla.ContentTelemetry.registerEvents("page.interaction", {
  "click": {
    methods: ["click"],
    objects: ["red_button", "blue_button"],
  }
});
// Now events can be recorded.
Mozilla.ContentTelemetry.recordEvent("page.interaction", "click", "red_button");

Mozilla.ContentTelemetry.recordEvent()

Mozilla.ContentTelemetry.recordEvent(category, method, object, value, extra);

Record a registered event. This accepts the same parameters and is subject to the same limitation as Services.telemetry.recordEvent(). See the events documentation for the definitive reference.

Example:

Mozilla.ContentTelemetry.recordEvent("ui", "click", "reload-btn");
// event: [543345, "ui", "click", "reload-btn"]
Mozilla.ContentTelemetry.recordEvent("ui", "search", "search-bar", "google");
// event: [89438, "ui", "search", "search-bar", "google"]
Mozilla.ContentTelemetry.recordEvent("ui", "completion", "search-bar", "yahoo",
                                     {"querylen": "7", "results": "23"});
// event: [982134, "ui", "completion", "search-bar", "yahoo",
//           {"qerylen": "7", "results": "23"}]

Data Review

Adding the hc_telemetry permission for a new domain in browser/app/permissions requires Data Collection Review as we are enabling a new method of data collection.

Giving a domain permission to use Hybrid Content Telemetry also gives any Extensions running on this domain permission to use Hybrid Content Telemetry. If the domain is already on the list of restricted domains (configured by the extensions.webextensions.restrictedDomains preference), Extensions don’t run on this domain and therefore cannot access the Hybrid Content Telemetry API. No additional approval is necessary.

If the domain is not on that list, you need additional privacy review. In that case request help from the Telemetry team.

Testing

In order to test Hybrid Content Telemetry integrations, the permission API can be used to enable certain hosts. The Services.perms.add API is available in the Browser Console as well as in xpcshell and mochi tests with access to the Services.* APIs.

The respective hc_telemetry permission needs to be set before any pages on that host load the HybridContentTelemetry-lib.js file.

Manual testing

After starting the browser, open the Browser Console (Tools -> Web Developer -> Browser Console). To enable Hybrid Content Telemetry on https://example.mozilla.org, execute this code snippet in the console:

let hostURI = Services.io.newURI("https://example.mozilla.org");
Services.perms.add(hostURI, "hc_telemetry", Services.perms.ALLOW_ACTION);

Afterwards load the page on https://example.mozilla.org and it will be able to record Telemetry data.

Note

Manual testing requires a host that handles HTTPS connections, as this kind of collection is only allowed on secure hosts. To allow for local testing, a local proxy capable of handling HTTPS connection is required.

Automated testing

In test frameworks with privileged access the permission can be set in the head.js or during test setup. Add the code snippet in your head.js to enable Hybrid Content ContentTelemetry on https://example.mozilla.org:

let hostURI = Services.io.newURI("https://example.mozilla.org");
Services.perms.add(hostURI, "hc_telemetry", Services.perms.ALLOW_ACTION);

Version History

  • Firefox 59: Initial hybrid content telemetry support (bug 1417473).