On Wednesday, November 1, 2017, Steve Barnes <gadgetsteve@live.co.uk> wrote:


On 01/11/2017 06:54, Wes Turner wrote:
> Suggestions to help to minimize unnecessary logged bandwidth use and
> even work with a closed loop LAN:
>
> This reads from the filesystem:
>
>      import requests
>
> This would read from the PyPi service over the network bandwidth:
>
>     #!pip install -U requests
>     #%run pip install -U requests
>
>     #pip('install -U requests')
>
> This doesn't work because you SHOULD restart the interpreter after
> running pip (because imports are cached):
>
>      import requests
>      !pip install -U requests
>      import requests
>
> Some tips on running educational environments for beginners (optionally
> in a lab):
>
<Snipped a lot of good stuff>

One tip that I have used when teaching python in a closed, (sometimes
internet free environment), was to pre-prepare by, in an on-line
environment:

  1. Create a virtual environment with the version of Python that I am
going to be teaching on the target platform
  2. Activate that environment
  3. Ensure that I am On-line
  4. Download the pip install packages that I know I will need by using
`pip download` to download but not install the packages, ideally using
the -r requirements.txt syntax, (plus any windows specific builds from
Christoph Gohlke's site).
  5. Go Off-line and run pip install with the downloaded package - if I
hit any errors due to packages having unspecified dependencies add those
to the requirements list and repeat from 3. (While I am at it I often
log an issue with the package maintainer).
  6. A fast, personal, run through my lesson plan to ensure that I
haven't missed anything.

I normally also download a few goodies that might not be essential to
the lesson but that can act as a teaser for the more interested students.

At the start of the first lesson I give the students the downloaded
packages directory, usually on a USB key, and get them to pip install
them while explaining the difference between local and on-line installation.

That works. You could also host the packages with devpi or just a static HTTP server.

As a transparent cache, if you test your ``requirements.txt`` with each OS/CPU_architecture combination, DevPi will store and serve each package to everyone at once.

So do you do (in a virtualenv):

  pip install --download ./dir -r requirements.txt

And then

  pip install --no-index --find-links ./dir -r requirements.text

Like in the pip docs?

https://pip.pypa.io/en/stable/user_guide/#installing-from-local-packages

DevPi can host package documentation.
https://devpi.net/docs/devpi/devpi/stable/+doc/userman/devpi_packages.html#uploading-documentation *

GitLab Pages can host package documentation and any static HTML pages (e.g. the CPython docs) alongside **the source**
https://docs.gitlab.com/ce/user/project/pages/index.html

https://github.com/python/cpython/tree/3.6/Doc


ReadTheDocs can host Sphinx docs and can be run in a Docker container for an internet-free LAN:
https://github.com/rtfd/readthedocs-docker-images
 

I know that I could save having to get the students to run pip by
packaging up the virtual environment as a portable, or using by
pyInstaller, but having them run pip on the local downloads gives me a
chance to explain how to do it in the wild.

AFAIU, YMMV with ``virtualenv --relocatable``; and it certainly doesn't do all combinations of OS and processor architecture:

https://virtualenv.pypa.io/en/stable/userguide/#making-environments-relocatable

itertools.combinations(
  ['win', 'mac', 'lin', '', '686', 'x86_64', 'ARM'], 2)
 

BTW while Docker is great for this it is a whole other learning
experience, (plus getting it running with some corporate security &
anti-virus can be quite a challenge).
 
Yeah, hosting Docker containers with Kubernetes across a couple extra workstations is initially more work than creating a few USB keys and waiting for everyone's virtualenvs to converge (with ``$ pip install``, ``!PIP_INDEX='' pip install``, and now a new pip GUI button press sequence).
 

These USB keys are often re-used by other co-workers as a getting
started or after my computer got changed/re-imaged starting point.

Wouldn't it be create if, just like oldschool floppies, there was a way to break off the sliding write protect tab of a USB stick?

https://en.wikipedia.org/wiki/USB_flash_drive_security#Malware_infections

CD-ROM and DVD-ROM drives seem to be more and more scare these days.
 

--
Steve (Gadget) Barnes
Any opinions in this message are my personal opinions and do not reflect
those of my employer.

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