/dev/tty does not map to the terminal allocated with "docker run -t" about moby HOT 3 CLOSED

This causes interactive commands to fail when they rely on the ability to open /dev/tty. For example:

• git clone on a private repository (when requesting username and password)
• apt-get install (when requesting information interactively, eg. upon installing mysql-server)

from moby.

@Andrea and I have played with a few knobs to find the source of the problem, with interesting results.

Knob 1: call setsid() and set the controlling terminal to fd 0: http://pastie.org/private/z73dibby22bmuiiujwjf1g#10

--> This causes 'docker run -i -t -a base /bin/bash' to fail, with 'invalid ioctl for device'.

Knob 2: leaving knob 1 in place, execute the command directly instead of going through lxc-start: http://pastie.org/private/z73dibby22bmuiiujwjf1g#18

--> This fixes the problem introduced by knob 1 (but doesn't fix /dev/tty).

In short, it seems that lxc-start itself messes with tty allocation in a non-trivial way, and at the very least we should understand what it does if we hope to fix this /dev/tty issue.

from moby.

This part of lxc's source seems relevant: https://github.com/lxc/lxc/blob/staging/src/lxc/conf.c#L671

It is called by lxc_start.

from moby.