It works fine until I get to the xvfb part.
When I run the script I get: "Element is not currently visible" for the "searchselector", same selector worked in the X11 part of TECH58. I thought it was a page/element load issue so I put in WebDriverWait until presence_of_element_located, it seems the element is present but not visible. I also tried visibility_of_element_located, but it does not pass this. I upped the time out to 100 secs.

The same script runs when I use the X11 style command line (see below)

docker run --rm -v $(pwd):/mnt selenium sh -c "xvfb-run -s '-screen 0 1024x768x24 -extension RANDR'\
> python /mnt/myscript.py"
Visiting github
Performing search
Traceback (most recent call last):
  File "/mnt/myscript.py", line 8, in <module>
    searchbox.send_keys('docker-in-practice\n')
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/remote/webelement.py", line 322, in send_keys
    self._execute(Command.SEND_KEYS_TO_ELEMENT, {'value': keys_to_typing(value)})
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/remote/webelement.py", line 457, in _execute
    return self._parent.execute(command, params)
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/remote/webdriver.py", line 233, in execute
    self.error_handler.check_response(response)
  File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/remote/errorhandler.py", line 194, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.ElementNotVisibleException: Message: Element is not currently visible and so may not be interacted with
Stacktrace:
    at fxdriver.preconditions.visible (file:///tmp/tmpbGp3_A/extensions/fxdriver@googlecode.com/components/command-processor.js:10092)
    at DelayedCommand.prototype.checkPreconditions_ (file:///tmp/tmpbGp3_A/extensions/fxdriver@googlecode.com/components/command-processor.js:12644)
    at DelayedCommand.prototype.executeInternal_/h (file:///tmp/tmpbGp3_A/extensions/fxdriver@googlecode.com/components/command-processor.js:12661)
    at DelayedCommand.prototype.executeInternal_ (file:///tmp/tmpbGp3_A/extensions/fxdriver@googlecode.com/components/command-processor.js:12666)
    at DelayedCommand.prototype.execute/< (file:///tmp/tmpbGp3_A/extensions/fxdriver@googlecode.com/components/command-processor.js:12608)

It works when I do this:

#!/bin/bash
docker run -e DISPLAY=$DISPLAY \
  -v /tmp/.X11-unix:/tmp/.X11-unix \
  --hostname=$HOSTNAME \
  -v $HOME/.Xauthority:/root/.Xauthority \
  -v $(pwd):/mnt \
  -it selenium bash

<on-the-container>$ python /mnt/myscript.py

has anybody run this example? I'm wondering if there is something I am doing incorrectly, as I am new to docker and I don't know python.
like I said above, the same script runs successfully with X11, but gets hung up with xvfb
- thanks

see: An element can't be clicked when the browser controlled by Selenium is displayed through xvfb #5828
https://github.com/seleniumhq/selenium-google-code-issue-archive/issues/5828

add the following line

from selenium import webdriver
b = webdriver.Firefox()
b.set_window_size(1024, 768)    ### Add this line, Must match  command line for xvfb screen

xvfb-run -s '-screen 0 1024x768x24 -extension RANDR'

please update code sample

Hi mancocapac, thanks for the detailed investigation and the fix

Unfortunately, I'm unable to check this right now as a recent firefox update in the Ubuntu repositories has broken selenium entirely (https://github.com/SeleniumHQ/selenium/issues/2110).

For when the fixed firefox is released, can you confirm you were using an Ubuntu 14.04 image? I tested this technique on multiple computers, so I'm a little surprise that it's broken! Such is the price of progress I suppose.

Aidan