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Bug 1113092 - `docker run` fails when attaching stderr in tty mode
Summary: `docker run` fails when attaching stderr in tty mode
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: docker
Version: 7.0
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Matthew Heon
QA Contact: Virtualization Bugs
URL:
Whiteboard:
Depends On:
Blocks: 1109938
TreeView+ depends on / blocked
 
Reported: 2014-06-25 12:25 UTC by Lukáš Doktor
Modified: 2019-03-06 01:21 UTC (History)
5 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2014-09-18 20:45:53 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)
output of "docker -D run -a stderr -t fedora bash -c exit" command (11.28 KB, text/plain)
2014-06-25 12:25 UTC, Lukáš Doktor 		no flags Details
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Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2014:1266 0 normal SHIPPED_LIVE docker bug fix and enhancement update 2014-09-19 00:45:12 UTC

Description Lukáš Doktor 2014-06-25 12:25:35 UTC 
Created attachment 912078 [details]
output of "docker -D run -a stderr -t fedora bash -c exit" command

Description of problem:
When I try to attach `-a stderr`, the process raises exception with nil pointer dereference.

Version-Release number of selected component (if applicable):
docker-0.11.1-10.el7.x86_64
docker-io-1.0.0-1.fc20.x86_64

How reproducible:
Always

Steps to Reproduce:
1. docker -D run -a stderr -t fedora bash

Actual results:
failure - tb attached

Expected results:
container should start

Additional info:
In non-tty mode it works perfectly.
Comment 2 Matthew Heon 2014-06-27 17:30:52 UTC 
Is there a reason why -a is allowed to be run with -t? Starting with -t implies that the stdin/out/err of the docker run process will all be attached to the new TTY; I don't see how attaching one of these signals again makes sense in that context. Running -a stdout -t, for example, breaks attaching stdin. 

Given this, I propose ignoring -a flags if -t is active. I'll raise this with upstream and see if they think this is a reasonable solution.
Comment 3 Daniel Walsh 2014-06-27 17:36:13 UTC 
I was thinking the same thing.  We can make the -a and -t conflict with each other if upstream agrees.
Comment 4 Matthew Heon 2014-06-27 17:54:41 UTC 
Issue created upstream about this: https://github.com/dotcloud/docker/issues/6736
Comment 5 Lukáš Doktor 2014-06-30 14:11:26 UTC 
It would be nice to make -a and -t conflict.
Comment 6 Matthew Heon 2014-07-16 15:13:07 UTC 
Upstream feels that there are use cases where -a and -t may be used together.

I've identified the root cause of the bug, though, and will be submitting a patch for it soon (https://github.com/dotcloud/docker/issues/6983)
Comment 7 Matthew Heon 2014-07-18 13:27:43 UTC 
Patch has been accepted by upstream. We'll be carrying it in our builds of Docker for RHEL7.
Comment 8 Matthew Heon 2014-07-18 20:36:06 UTC 
Fixed in docker-1.1.1-1
Comment 9 Lukáš Doktor 2014-07-21 14:32:42 UTC 
Hi Matthew, I can confirm it's not crashing. Unluckily I'm not convinced it works fine yet. I tested it with `ls non_existing_file` which should print into stderr "ls: cannot access non_existing_file: No such file or directory". When I use tty mode, it's printing it into stdout, when I use non-tty mode it prints it correctly into stderr:

TTY:
[root@localhost ~]# docker run -t -a stderr fedora ls non_existing_file
[root@localhost ~]# docker run -t -a stdout fedora ls non_existing_file
ls: cannot access non_existing_file: No such file or directory
NON-TTY:
[root@localhost ~]# docker run -a stderr fedora ls non_existing_file
ls: cannot access non_existing_file: No such file or directory
[root@localhost ~]# docker run -a stdout fedora ls non_existing_file
Comment 10 Matthew Heon 2014-07-21 14:44:11 UTC 
Confirmed, I can reproduce this locally.

This looks to be a server-side issue - in TTY mode, the server seems to multiplex stdout into stderr, which the client is unaware of. I'll look into fixing this.
Comment 11 Lukáš Doktor 2014-07-21 15:17:10 UTC 
OK, thank you. I'll set this to `verified` as it's not crashing now and create new BZ for the stdout/stderr multiplex issue to not lost the track...
Comment 12 Lukáš Doktor 2014-07-21 15:27:06 UTC 
https://bugzilla.redhat.com/show_bug.cgi?id=1121689
Comment 13 errata-xmlrpc 2014-09-18 20:45:53 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHBA-2014-1266.html
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