Profpatsch/users/Profpatsch/firefox-profiler

View full contents ↓

The “official” firefox profiler is hosted at https://profiler.firefox.com/. Firefox itself does not provide its own local-only profiler anymore, but any profiles you create (or upload) will be opened on the Mozilla-hosted website.

Mozilla employees assured me that currently no telemetry is used on profiler.firefox.com, but the linked privacy policy basically allows Mozilla to do any kind of data collection (breaching GDPR …).

However, it is possible to change the profiler Firefox uses to an arbitrary URL. In about:config, set the preference

devtools.performance.recording.ui-base-url

to http://localhost:5252 (or whichever port you use):

Firefox profiler URL setting

So if you want to host your profiler yourself (e.g. on your local machine or in your own company network (profiles are IP-critical pieces of data!), you can use this nix expression to build a simple golang binary which serves the javascript files.

nix run https://sources.profpatsch.de/Profpatsch.tar.gz#firefox-profiler

firefox-profiler(1)

firefox-profiler - serve the Firefox Profiler frontend locally

firefox-profiler [-port port] [-open file]

firefox-profiler is a standalone HTTP server that serves the Firefox Profiler web application from a single self-contained binary.

The official Firefox Profiler is hosted at https://profiler.firefox.com/. Firefox no longer ships its own local profiler; any profiles you capture are opened on the Mozilla-hosted website. While Mozilla employees have stated that no telemetry is currently collected, the linked privacy policy permits Mozilla to perform arbitrary data collection, which may conflict with GDPR obligations and is problematic for IP-sensitive profiling data such as company-internal performance work.

firefox-profiler solves this by building the profiler frontend from a pinned upstream commit and embedding it into a single binary, which serves both the JavaScript application and stub API endpoints from the same origin. The upload, delete, and URL-shortening API endpoints all return "501 Not Implemented" — the server is intended purely for local profile viewing, not sharing.

To use firefox-profiler, configure Firefox to open profiles with your local server instead of https://profiler.firefox.com/. In Firefox, go to about:config and set the preference devtools.performance.recording.ui-base-url to http://localhost:5252 (or whichever port you are using).

The arguments are as follows:

-port port

The TCP port to listen on. Defaults to 5252, or a random free port when -open is used.

-open file

Open a profile file directly in the browser. firefox-profiler serves the file at /cli/open/profile and opens the browser at the corresponding /from-url/ address. The route is de-registered after the first fetch so the profile data is not kept in memory, but the server itself keeps running. Implies a random port unless -port is also given.

The following endpoints are implemented:

GET /__lbheartbeat__

Returns 200 OK. Load-balancer liveness check.

GET /__heartbeat__

Returns 200 OK. Health check.

GET /__version__

Returns a JSON object with version information.

GET /

Serves the Firefox Profiler single-page application. All paths not matching a known static asset fall back to index.html for client-side routing.

The following endpoints return "501 Not Implemented":

POST /compressed-store

Profile upload (requires Google Cloud Storage in the original server).

DELETE /profile/token

Profile deletion.

POST /shorten

URL shortening (requires Bitly in the original server).

POST /expand

URL expansion.

Start the server on the default port:

$ firefox-profiler
firefox-profiler listening on http://localhost:5252

Open a profile file directly in the browser (random port, server stays running):

$ firefox-profiler -open profile.json.gz
firefox-profiler listening on http://localhost:48291
opening http://localhost:48291/from-url/http%3A%2F%2Flocalhost%3A48291%2Fcli%2Fopen%2Fprofile
profile served, route deactivated

Use a custom port:

$ firefox-profiler -port 8080

Build and run directly with Nix:

$ nix run git+https://codeberg.org/Profpatsch/Profpatsch#firefox-profiler -- -open profile.json.gz

Use a custom port:

$ firefox-profiler-server -port 8080

Build and run directly with Nix:

$ nix run git+https://codeberg.org/Profpatsch/Profpatsch#firefox-profiler

https://profiler.firefox.com/

Profpatsch