Quick Summary

The following document will list all the important about:config preferences that are used when installing a telemetry experiment. If there's anything missing from the list that should be included, please don't hesitate to contact me or add it yourself!

Setting about:config Preferences

Quick Note: Some of these are not listed in about:config and will need to be created manually

• devtools.chrome.enabled
  • enables browser chrome and add-on debugging toolboxes
• experiments.activeExperiment
  • Indicates if there's an experiment currently active/installed
• experiments.enabled
  • Indicates if the experiments are currently enabled/disabled (enabled by default)
• experiments.logging.dump
  • Example: Services.prefs.setBoolPref("experiments.logging.dump", true);
    • will also dump logs into stdout and the browser console
• experiments.logging.level
  • Example: Services.prefs.setCharPref("experiments.logging.level", "Trace");
    • Changing this to 0 or Trace will give you the ability to view the logs under the Browser Console. You'll have to enable Chrome and addon debugging. Please see Setting up Logging
• experiments.force-sample-value
  • Example: Services.prefs.setCharPref("experiments.force-sample-value", ".1"); (this will change the sample value to 10%)
    • The staging server uses a sample value that dictates what percentage of users will get the experiment, ensure this value matches the servers .JSON file or it will take you a very long time to retrieve the experiment from the server
• experiments.manifest.cert.checkAttributes
  • If you're connecting to a development or local staging server, change this to false or the certificate authentication will fail when contacting the staging server
• experiments.supported
  • Indicates if experiments are currently supported
• experiments.manifest.uri
  • Points to the manifest .JSON file that will be used to download and set the experiment
• experiments.manifest.fetchIntervalSeconds
  • Number of seconds before Firefox fetches the experiment manifest
• extensions.bootstrappedAddons
  • Ensure that experiments are not being added into this preference under about:config. This preference is the quick access cache that's used on startup to see what bootstrap extension to load when Firefox initially launches. This should only be listing currently installed add-ons in a JSON format