kubernetes: Initial terminal dimensions for `kubectl exec` are not set correctly

Is this a BUG REPORT or FEATURE REQUEST?: BUG REPORT

Uncomment only one, leave it on its own line:

/kind bug

/kind feature

What happened: kubectl exec -it used to set the terminal dimensions correctly. Now, they’re only set correctly if you resize the terminal. My theory is that this regressed due to underlying architectural changes in docker and how it creates exec processes, but I’m not 100% sure about that.

What you expected to happen: When you kubectl exec -it and inspect $COLUMNS or $LINES, the variables should reflect the current terminal size.

How to reproduce it (as minimally and precisely as possible):

resize your terminal to something that is not the standard 80x24
kubectl run --restart Never --image nginx nginx
kubectl exec -it nginx bash
echo $COLUMNS

Anything else we need to know?: Forked from #13585.

Environment:

Kubernetes version (use kubectl version): commit afc4506
OS (e.g. from /etc/os-release): Fedora 25
Kernel (e.g. uname -a): 4.8.6-300.fc25.x86_64
Others: docker-1.12.6-6.gitae7d637.fc25.x86_64

About this issue

Original URL
State: closed
Created 7 years ago
Comments: 24 (10 by maintainers)

Commits related to this issue

Merge pull request #47991 from ncdc/fix-initial-exec-terminal-dimensions Automatic merge from submit-queue Fix initial exec terminal dimensions **What this PR does / why we need it**: Delay attemp... — committed to kubernetes/kubernetes by deleted user 7 years ago
Merge pull request #51126 from chen-anders/anders/port-47991-to-release-1.6 Automatic merge from submit-queue Cherry Pick on 1.6 - Fix initial exec terminal dimensions (#47991) Cherry-picking #4799... — committed to kubernetes/kubernetes by deleted user 7 years ago

Most upvoted comments

This is still an issue. Is it being looked into?

DarrienG on Feb 5, 2019

Stock Ubuntu 18, and at our company we also use a proprietary build of Fedora 27, both with the same results.

With that said - Docker exec reports it fine, but opening say, Vim in a container deployed in Kubernetes vim gets maybe a 4th of the screen.

There was a provided script kshell in the previous thread:

if [ "$1" = "" ]; then
  echo "Usage: kshell <pod>"
  exit 1
fi
COLUMNS=`tput cols`
LINES=`tput lines`
TERM=xterm
kubectl exec -i -t $1 env COLUMNS=$COLUMNS LINES=$LINES TERM=$TERM bash

That makes the terminal report everything correctly, but stock kubectl does not.

DarrienG on Jan 8, 2019

Hmm, I still got the same result.

$ kubectl exec -it nginx bash
root@nginx:/# echo $COLUMNS
80

Environment:

Kubernetes version (use kubectl version):

$ kubectl version
Client Version: version.Info{Major:"1", Minor:"9", GitVersion:"v1.9.6", GitCommit:"9f8ebd171479bec0ada837d7ee641dec2f8c6dd1", GitTreeState:"clean", BuildDate:"2018-03-21T15:21:50Z", GoVersion:"go1.9.3", Compiler:"gc", Platform:"darwin/amd64"}
Server Version: version.Info{Major:"1", Minor:"9", GitVersion:"v1.9.6", GitCommit:"9f8ebd171479bec0ada837d7ee641dec2f8c6dd1", GitTreeState:"clean", BuildDate:"2018-03-21T15:13:31Z", GoVersion:"go1.9.3", Compiler:"gc", Platform:"linux/amd64"}

OS (e.g. from /etc/os-release): macOS Sierra 10.12.6 Kernel (e.g. uname -a):

Linux nginx 4.9.87-linuxkit-aufs #1 SMP Fri Mar 16 18:16:33 UTC 2018 x86_64 GNU/Linux

(Ran uname -a in nginx pod) Others: Docker for Mac Version 18.05.0-ce-mac66 (24545) edge channel

mtsmfm on May 23, 2018

Also still having the same issue.

Client Version: version.Info{Major:"1", Minor:"9", GitVersion:"v1.9.7", GitCommit:"dd5e1a2978fd0b97d9b78e1564398aeea7e7fe92", GitTreeState:"clean", BuildDate:"2018-04-19T00:05:56Z", GoVersion:"go1.9.3", Compiler:"gc", Platform:"darwin/amd64"}
Server Version: version.Info{Major:"1", Minor:"10", GitVersion:"v1.10.3", GitCommit:"2bba0127d85d5a46ab4b778548be28623b32d0b0", GitTreeState:"clean", BuildDate:"2018-05-21T09:05:37Z", GoVersion:"go1.9.3", Compiler:"gc", Platform:"linux/amd64"}

julienvincent on Jun 18, 2018

What happens if you do a normal kubectl exec -it, then resize the window? Does it report correctly after the resize?

ncdc on Jan 8, 2019