marionette

A Racket library that lets you control Firefox via the Marionette Protocol.

Quickstart

Install marionette:

$ raco pkg install marionette

Run Firefox with the -marionette flag:

$ /path/to/firefox -headless -marionette -safe-mode

Run this script:

#lang racket

(require marionette)

(call-with-browser!
  (lambda (b)
    (call-with-page! b
      (lambda (p)
        (page-goto! p "https://racket-lang.org")
        (call-with-page-screenshot! p
          (lambda (data)
            (define filename (make-temporary-file "~a.png"))
            (with-output-to-file filename
              #:exists 'truncate/replace
              (lambda ()
                (write-bytes data)))

            (system* (find-executable-path "open") filename)))))))

Tips

To run a headless, marionette-enabled Firefox while you've got another instance of the browser open, add the -no-remote flag:

$ /path/to/firefox -no-remote -headless -marionette -safe-mode

It's advisable that you use a separate profile as well:

$ /path/to/firefox -P marionette -no-remote -headless -marionette -safe-mode

You can create new profiles by visiting about:profiles in the browser.