Docker tty is not a tty with docker exec

[MichaelBitard]

When I enter a running docker with "docker exec -ti mydockerinstance /bin/bash"

tty returns: not a tty and tmux doesn't work.

I tried several things from #728:
docker exec -ti mydockerinstance sh -c "exec >/dev/tty 2>/dev/tty </dev/tty && /usr/bin/tmux -s /bin/bash"
getty tty
but nothing succeded.

[jessfraz]

what is $TERM set to, maybe try setting it to xterm ?

[MichaelBitard]

TERM is already set to xterm.

When I launch tmux -vvvv the tmux-client.log is empty but the tmux-server.log contains:

server started, pid 639
socket path /tmp/tmux-1000/default
new client 7
got 14 from client 7
got 14 from client 7
got 14 from client 7
got 14 from client 7
got 14 from client 7
got 14 from client 7
got 14 from client 7
got 14 from client 7
got 14 from client 7
got 14 from client 7
got 14 from client 7
got 6 from client 7
fatal: tty_init: ttyname failed

[MichaelBitard]

When I try getty tty it just hang for a few seconds then give back the prompt, nothing changed

[MichaelBitard]

Ok, I managed to get something to work with script -c tmux but it's still a trick.

I really think this is a bug because:
If I do docker run --rm -ti my_image /bin/bash I get a tty and tmux works like a charm
(tty returns /dev/console)

But if I do docker run --rm -ti my_image then docker exec -ti /bin/bash this time it doesn't work, (tty returns not a tty)

[razic]

i'm also running into this issue.

docker@boot2docker:~$ docker --version
Docker version 1.3.0, build c78088f

the only solution i found was to use script as well:

docker exec -ti container script /dev/null

[razic]

I was actually able to run docker exec -ti container tmux this morning.

[MichaelBitard]

Wow, that's great, do you know what changed? Are you able to reproduce this?

[razic]

Scratch that. Can't seem to reproduce.

[razic]

I'm experiencing weird behavior with environment variables, tmux and vim...

For example, when I run:

docker exec -ti razic script /dev/null -c 'tmux'

The container launches. But, then I run vim .bash_profile inside a tmux pane, the colors are all screwed up:

If I run the same command above, but pass the -c option to tmux:

docker exec -ti razic script /dev/null -c 'tmux -c "vim .bash_profile"'

I get colors correct:

Seem like tmux's -c option loads the user environment correctly before running the vim command.

Basically I can only launch vim correctly from inside a tmux pane by logging into bash first:

docker exec -ti razic script /dev/null -c 'bash -ilc tmux'

or all manually:

docker exec -ti razic script /dev/null

then from inside the container:

 # colors are good without tmux
vim .bash_profile

# start tmux
tmux

# colors are not good in tmux
vim .bash_profile

# detach tmux
[detached]

# log in to bash
bash -il

# start tmux
tmux

# colors are good
vim .bash_profile

[jessfraz]

can you all let me know if this is still a relevant issue.

[MichaelBitard]

Yes, it's still relevant.

Client version: 1.4.1
Client API version: 1.16
Go version (client): go1.3.3
Git commit (client): 5bc2ff8
OS/Arch (client): linux/amd64
Server version: 1.4.1
Server API version: 1.16
Go version (server): go1.3.3
Git commit (server): 5bc2ff8

Kernel Version: 3.13.0-36-generic
Operating System: Ubuntu 14.04.1 LTS

[michaelsbradleyjr]

I'm experiencing the same problem, docker 1.4.1.

[cpuguy83]

So, what image are you running, and with what run command, and what exec command?

[michaelsbradleyjr]

@cpuguy83 I am running an image based on ubuntu:14.04 via the most recent boot2docker on a mac laptop (yosemite). I have experienced the same problem with all previous versions of docker / boot2docker which I've used in recent months.

Here are the steps which can be used to reproduce the problem.

# on the docker host
docker run -it --rm --name foo ubuntu:14.04 bash
# inside the container
apt-get update
apt-get install tmux
tmux

In another terminal on the host:

docker exec -it foo bash
# inside the container
tmux ls

The latter command will fail, and tmux will crash in the original terminal, in some cases killing the container altogether and/or turning it into a container-zombie (in which case one must boot2docker restart and then docker rm to get rid of it).

[MichaelBitard]

It seems that any image which has bash in it has the problem.

Step to reproduce:

docker run --name no_tty -dti ubuntu /bin/bash (or whatever)
docker exec -ti no_tty /bin/bash
tty -> not a tty

[michaelsbradleyjr]

Any chance a fix for this bug will land in 1.5.0?

[cpuguy83]

So what is the purpose of using docker exec to fire up a tmux session?

[MichaelBitard]

We use docker with ansible as a developer workstation, with this we have a
reproductible environment among all the developers
And as a developer, I use tmux. QED :)

If you are interested, here is a quickstarter
https://github.com/MichaelBitard/docker-ansible

Le Thu Feb 05 2015 at 5:27:03 PM, Brian Goff notifications@github.com a
écrit :

So what is the purpose of using docker exec to fire up a tmux session?

—
Reply to this email directly or view it on GitHub
#8755 (comment).

[michaelsbradleyjr]

@cpuguy83 when working in "dev mode" with my containers, I generally pass -it to docker run and fire up tmux (i.e. when it seems useful to me to do so). It would be extremely useful (to me) to be able to fire up tmux in the context of exec -it, regardless of whether -it had been passed to run. At present, since the environment provided by exec is not a tty – even when invoked with -it flags (a pseudo-TTY is not actually allocated, apparently) – it's not possible to use it in this way. At the very least, perhaps the --help output of exec ought to be amended to indicate that its -it mode has limitations relative to run -it.

In other words, if this is a bug, it seems like it should be fixed. If it can't be fixed at present, or if it's a foreseen and/or intended limitation of exec, then an indication should be provided in the output of --help.

[razic]

i also use docker for my development environment. this is why i run tmux
inside a container.

On Thu, Feb 5, 2015 at 1:04 PM, Michael Bradley notifications@github.com
wrote:

@cpuguy83 https://github.com/cpuguy83 when working in "dev mode" with
my containers, I generally pass -it to docker run and fire up tmux (i.e.
when it seems useful to me to do so). It would be extremely useful (to me)
to be able to fire up tmux in the context of exec -it, regardless of
whether -it had been passed to run. At present, since the environment
provided by exec is not a tty – even when invoked with -it flags (a
pseudo-TTY is not actually allocated, apparently) – it's not possible to
use it in this way. At the very least, perhaps the --help output of exec
ought to be amended to indicate that it's -it option has limitations
relative to run -it.

—
Reply to this email directly or view it on GitHub
#8755 (comment).

[dbabits]

@michaelsbradleyjr +1 on Michael's comments.
To add a bit more to the use case:
I use a docker image as my dev environment.

The connection to the host often drops.

The image itself is designed to run monit(proc monitor), not bash, and I connect to it by way of -exec -ti bash

Then I would like to tmux attach and be back to where I left off.

If somebody has a better suggestion how to accomplish this, I appreciate your comments.

[pikeas]

+1!

[ninrod]

@razic this stuff is so advanced that I can't follow a word of what you've just said, but sounds promising. I'm eagerly waiting for this. Thanks for working on it.

[razic]

Quick update... I was able to get a container running via ctr, so I think I may have gotten over that hump. I've been learning a lot about how the whole thing works (containerd-shim etc). I think I now have everything I need to be able to test my changes once I implement them. Will provide another update soon.

[crosbymichael]

Fixed by #33007

[michaelsbradleyjr]

And there was much rejoicing.

[ninrod]

awesome!!!! please gentleman, in what docker version can I grab this fix?

[thaJeztah]

This will be in 17.06

[LinusU]

Will this land in an edge release before that? Was it landed in 17.05.0-ce-mac11? Any pointers on where to check this? :)

[thaJeztah]

No, this won't be in 17.05, only 17.06 and upward

[LinusU]

Okay, thank you! Is there a release date set? Sorry for asking so many questions :) tried googling first but didn't find it, maybe I just a missed it though...

[thaJeztah]

The version is YY.MM, and we target first week of the month, so first week of June, with release candidates before that

[LinusU]

Ah, that's great to know, thank you!

[zrml]

Great news @thaJeztah !

[ninrod]

Hi @thaJeztah, is 17.06 going to land in in june or will it be rescheduled for july? if so, will it be 17.07 instead? just wan't to be sure regarding the version that will have this fix landed.

[razic]

zacharys-pro:dev razic$ docker run --rm -t -d ubuntu bash
83c292c8e2d13d1b1a8b34680f3fb95c2b2b3fef71d4ce2b6e12c954ae50965a
zacharys-pro:dev razic$ Docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
83c292c8e2d1        ubuntu              "bash"              2 seconds ago       Up 1 second                             xenodochial_bardeen
zacharys-pro:dev razic$ docker exec -ti xenodochial_bardeen tty
/dev/pts/1
zacharys-pro:dev razic$ docker version
Client:
 Version:      17.06.0-ce
 API version:  1.30
 Go version:   go1.8.3
 Git commit:   02c1d87
 Built:        Fri Jun 23 21:31:53 2017
 OS/Arch:      darwin/amd64

Server:
 Version:      17.06.0-ce
 API version:  1.30 (minimum version 1.12)
 Go version:   go1.8.3
 Git commit:   02c1d87
 Built:        Fri Jun 23 21:51:55 2017
 OS/Arch:      linux/amd64
 Experimental: true

Great work everyone. Thank you very much.

[ninrod]

is this released? where?

[razic]

@ninrod I've included the version information in the output. This is fixed in version 17.06.0-ce, which is the most current stable version. If you are using Docker for Mac, you can simply restart the application, and you should be prompted to upgrade.

[ninrod]

Oh. but this is not ready yet for docker for windows, right?

[zrml]

just tested it on Docker-for-Mac latest and it works. I'm a happy man :-)