gliderlabs/docker-alpine

Python2 cannot read keyboard input device

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#206 opened on Aug 22, 2016

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Description

I'm trying to read usb keyboard inside alpine docker container.

Run container

# docker run --privileged --rm -it -v /dev/input:/dev/input alpine sh

/ # ls /dev/input/by-path/
pci-0000:00:01.2-usb-0:1:1.0-event-mouse  platform-i8042-serio-1-event-mouse
pci-0000:00:01.2-usb-0:1:1.0-mouse        platform-i8042-serio-1-mouse
platform-i8042-serio-0-event-kbd          platform-pcspkr-event-spkr

Run python2 (Raise error)

/ # apk add -U python
/ # python
Python 2.7.12 (default, Jun 29 2016, 08:57:23)
[GCC 5.3.0] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> kbd = open('/dev/input/by-path/platform-i8042-serio-0-event-kbd', 'rb')
>>> kbd.read(16)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IOError: [Errno 22] Invalid argument
>>> exit()

Run python3 (No error)

/ # apk add python3
/ # python3
Python 3.5.1 (default, May 30 2016, 16:01:04)
[GCC 5.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> kbd = open('/dev/input/by-path/platform-i8042-serio-0-event-kbd', 'rb')
>>> kbd.read(16)
^C

Contributor guide

Tech stack
pythondocker
Domain
infrastructure
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic Python knowledgeFamiliarity with Docker
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
Investigate the difference between Python2 and Python3 file reading behavior on Linux input devices. Check if the Python2 package in Alpine is missing unbuffered mode or uses different flags. Look at the open() call with 'rb' mode; Python2 might require a different buffer size or device specific handling. Consider updating to Python3 or patching the Python2 package.