I screwed up with git and managed to delete the code I had just written... but it was still running in a process in a docker container. Here's how I got it back.

Attach a shell to the docker container

Install GDB (needed by pyrasite)

    apt-get update && apt-get install gdb

Install pyrasite - this well let you attach a Python shell to the still-running process.

    pip install pyrasite

Install uncompyle2, which will let you get Python source code back from in-memory code objects:

    pip install uncompyle2

Find the PID of the process that is still running

    ps aux | grep python

Attach an interactive prompt using pyrasite

    pyrasite-shell <PID>

Now you're in an interactive prompt! Import the code you need to recover:

    >>> from my_package import my_module

Figure out which functions and classes you need to recover:

    >>> dir(my_module)
    ['MyClass', 'my_function']

Decompile the function into source code:

    >>> import uncompyle6
    >>> import sys
    >>> uncompyle6.main.uncompyle(
        2.7, my_module.my_function.func_code, sys.stdout
    )
    # uncompyle6 version 2.9.10
    # Python bytecode 2.7
    # Decompiled from: Python 2.7.12 (default, Nov 19 2016, 06:48:10) 
    # [GCC 5.4.0 20160609]
    # Embedded file name: /srv/destination_service/destination_service/wsgi.py
    function_body = "appears here"

For the class, you'll need to decompile each method in turn:

    >>> uncompyle6.main.uncompyle(
        2.7, my_module.MyClass.my_method.im_func.func_code, sys.stdout
    )
    # uncompyle6 version 2.9.10
    # Python bytecode 2.7
    # Decompiled from: Python 2.7.12 (default, Nov 19 2016, 06:48:10) 
    # [GCC 5.4.0 20160609]
    # Embedded file name: /srv/my_package/my_module.py
    class_method_body = "appears here"