I am unable to execute netcat command within docker bash terminal? - bash

I am a beginner in docker . I have installed docker-ce in my ubuntu 18.04 machine using commandsudo apt install docker-ce
As part of a tutorial , I am trying to establish connection between containers by executing series of below commands.
Below command will turn on ports 1234/4321 to listen to traffic inside/outside of containers i'm going to use.
root#ghost-SVE9999CNS:/home/ghost# docker run --rm -ti -p 1234:1234 -p 4321:4321 --name echo-server ubuntu:18.04 bash
Now, I wanted to run netcat commands within docker bash terminal.
root#xxxyyyyzzzz12:/# nc -lp 1234 | nc -lp 4321
Once i inovke above command from my terminal.. Its giving errors "nc: command not found"
bash: nc: command not found
bash: nc: command not found
Later, I have done enough research and i never found any official docker solution for this problem.
Please could anyone help me out installing netcat within docker-ce.
I've tried commands like below.
apt-get install netstat
apt-get install nc
But, no luck.

nc is not installed by default on ubuntu:18.04 image, so you have to install it :
apt-get update && apt-get install -y netcat
apt-get update is necessary to first update list of packages (when the container is started, this list is empty). Once done, you can run nc -lp 1234 from the container.
To test all works as you expected, you can then :
run from a shell (on your host) something like telnet container_ip 1234 or telnet localhost 1234 (since ports have been forwarded)
type something
look at the container output to see what you typed in your host shell

It is not necessary to use ubuntu:18.04 to follow the tutorial, you can use ubuntu:14.04 for example, in which nc installed by default.
docker run --rm -ti -p 1234:1234 -p 4321:4321 --name echo-server ubuntu:14.04 bash

Related

Docker keeps complaining about the input device is not TTY

I'm using Windows-10 and using GitBash entering in the command
$ docker run -ti ubuntu:latest bash
And it gives me this error message
"the input device is not a TTY. If you are using mintty, try prefixing the command with 'winpty'"
And so I placed in this command to switch to winpty
$ winpty docker.exe run -it --rm ubuntu:14.04 /bin/bash
And it still doesn't work. I know my ports are running correctly, and I installed ubuntu correctly.
At windows 10 and git bash this works for me:
winpty docker exec -it "CONTAINTER ID" sh

docker error on windows : the input device is not a TTY. If you are using mintty, try prefixing the command with 'winpty' [duplicate]

This question already has answers here:
Error "The input device is not a TTY"
(16 answers)
Closed 2 years ago.
After I run this
docker run --rm -v "/c/users/vipul rao/documents/github/wappalyzer:/opt/wappalyzer" -it wappalyzer/dev
I am getting the following error
the input device is not a TTY. If you are using mintty, try prefixing the command with 'winpty'
What should I use here? I am running Docker on Windows 8 in MINGW64.
As suggested by the error message you obtain, you should try to use winpty (which is installed by default with Git-Bash) and thus run:
winpty docker run --rm -v "/c/users/vipul rao/documents/github/wappalyzer:/opt/wappalyzer" -it wappalyzer/dev
If this works, you may want to set a Bash alias to avoid manually prepending winpty all the time:
echo "alias docker='winpty docker'" >> ~/.bashrc
or
echo "alias docker='winpty docker'" >> ~/.bash_profile
If you are using Git Bash you can try like this
winpty docker run -it ubuntu
This problem occurs when running with -it option using bash terminal on windows. You can use Powershell to resolve this issue.
This works for me.
I am using git bash on windows
winpty docker-compose exec app ls -l
Remove -it from the command. If you want to keep it interactive then keep -i
Don't use alias docker="winpty docker". It solves your problem but break pipes.
$ winpty docker run -ti ubuntu
root#e85cff7d1670:/# exit
$ wintpy docker run ubuntu bash HELLO
HELLO
$ wintpy docker run ubuntu bash HELLO | cat
stdout is not a tty
Copy this to your .bashrc. This script uses winpty docker only if -ti is used.
function docker(){
for param; do if [[ "$param" == "-ti" ]] || [[ "$param" == "-it" ]]; then
winpty docker "$#"; return
fi; done;
command docker "$#"
}
docker run -ti ubuntu becomes winpty docker run -ti ubuntu avoids error: the input device is not a TTY. If you are using mintty, try prefixing the command with 'winpty'"
docker run ubuntu echo "what's up" | cat becomes command docker run echo "what'up" | cat avoids error: stdout is not a tty
The script only looks if there is a '-it' parameter without checking if it is inside a 'docker run' sentence... but it does the trick for my uses.
Did you start "Docker Quickstart Terminal"? I was trying to run
$ docker run -i -t redcricket/react-tutorial:latest /bin/bash
on windows from a Cygwin bash shell and got the same error:
the input device is not a TTY. If you are using mintty, try prefixing the command with 'winpty'
Then I remembered that when I installed docker on my windows 10 system something called "Docker Quickstart Terminal" got installed. You need to start that first from that dumb windows 'Type here to search' thing on the task bar:
That launches this …
… you can run your docker commands there without getting that error or running winpty.
The problem is with gitbash however with the powershell it is working fine ..
Happened to me. From Git Bash, on Windows 8 running Docker Toolbox. There are two things happening. From git bash, we do not seem to have complete escalated privilege to the docker daemon (even though i'm running git bash with administrative privileges).
Thus:
Try running the command from your docker terminal. (gives you privilege).
To compensate for errors from Window's folder naming formats, don't forget to quote the path.. (to escape spaces and/or capitalization errors) say
From:
docker run -v $(pwd):/data image_ref
To:
docker run -v "$(pwd):/data" image_ref
(notice the enclosing quotes in the latter around $(pwd):/data).
Just add 'winpty' in start of your cmd ,Try below:
$ winpty docker.exe run --rm -v "/c/users/vipul rao/documents/github/wappalyzer:/opt/wappalyzer" -it wappalyzer/dev
Why this happens? More details here:
http://willi.am/blog/2016/08/08/docker-for-windows-interactive-sessions-in-mintty-git-bash/
Got this error for running docker-compose exec workspace bash
So just prefix with winpty winpty docker-compose exec workspace bash
It may be that you're not running your commands within the Docker terminal. If you don't, you may not be properly connected to the Docker daemon and won't be able to interact correctly.
Make sure you're running commands in the actual Docker Terminal.
For those using WSL and running Docker for windows inside of cmder or conemu I would recommend to not to use Docker which is installed on windows in 'Program Files' but instead install Docker inside WSL on ubuntu/linux. Do remember though that you can't run Docker itself from within WSL, you must connect to Docker running on windows from the linux Docker client installed in WSL.
To install Docker on WSL
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
sudo apt-get update
sudo apt-get install docker-ce
Your options for running actual Docker commands are to either:
Connect to Docker using the switch -H
docker -H localhost:2375 run -it -v /mnt/c/code:/var/app -w "/var/app" centos:7
Or set the environment variable docker_host
export DOCKER_HOST=tcp://localhost:2375
Either way you are now be able to interactively connect to a running Docker container
you can try with Cmder tool it will work. Its not working with Gitbash
In addition to above mentioned solutions.
In case you are getting this error for docker attach
example: docker attach alpine1
error: the input device is not a TTY. If you are using mintty, try prefixing the command with 'winpty'
Solution: Adding winpty before docker command i.e. winpty docker attach should work.
example: winpty docker attach alpine1
Note: I was getting this error while using base on windows and this solution worked for me.
I had the same error when trying to run the docker-compose exec command.
In the help documentation docker-compose exec --help it shows how you can disable the pseudo-tty allocation by adding -T to your command options in the following way:
docker-compose exec -T
From the help documentation:
-T Disable pseudo-tty allocation. By default docker-compose exec allocates a TTY.
If you are using gitbash the problem is when setting the terminal emulator for for using with Git bash.setting the emurator
Instead you can change the emulator to the first options or use the
winpty command before your docker run command

Ahow to use multiple terminals in the docker container?

I know it is weird to use multiple terminals in the docker container.
My purpose is to test some commands and build a dockerfile with these commands finally.
So I need to use multiple terminals, say, two. One is running some commands, the other is used to test that commands.
If I use a real machine, I can ssh it to use multiple terminals, but in docker, how can I do this?
Maybe the solution is to run docker with CMD /bin/bash, and in that bash, using screen?
EDIT
In my situation, one shell run a server program, the other run a client program to test the server program. Because the server program and client program are compiled together. So, the default link method in docker is not suitable.
The docker way would be to run the server in one container and the client in another. You can use links to make the server visible from the client and you can use volumes to make the files at the server available from the client. If you really want to have two terminals to the same container there is nothing stopping you from using ssh. I tested this docker server:
from: https://docs.docker.com/examples/running_ssh_service/
# sshd
#
# VERSION 0.0.1
FROM ubuntu:14.04
MAINTAINER Thatcher R. Peskens "thatcher#dotcloud.com"
RUN apt-get update && apt-get install -y openssh-server
RUN mkdir /var/run/sshd
RUN echo 'root:screencast' | chpasswd
RUN sed -i 's/PermitRootLogin without-password/PermitRootLogin yes/' /etc/ssh/sshd_config
EXPOSE 22
CMD ["/usr/sbin/sshd", "-D"]
You need to base this image on your image or the otherway around to get all the functionality together. After you have built and started your container you can get it's IP using
docker inspect <id or name of container>
from the docker host you can now ssh in with root and the password from the docker file. Now you can spawn as many ssh clients as you want. I tested with:
while true; do echo "test" >> tmpfile; sleep 1; done
from one client and
tail -f tmpfile
from another
If I understand correctly the problem, then you can use nsenter.
Assuming you have a running docker named nginx (with nginx started), run the following command from the host:
nsenter -m -u -i -n -p -t `docker inspect --format {{.State.Pid}} nginx`
This will start a program in the given name space of the PID (default $SHELL).
You can run more then one shell by issuing it more then once (from the host). Then you can run any binary that exist in the given docker or tail, rm, etc files. For example, tail the log file of nginx.
Further information can be found in the nsenter man.
If you want to just play around, you can run sshd in your image and explore it the way you are used to:
docker run -d -p 22 your_image /usr/sbin/sshd -D
When you are done with your explorations, you can proceed to create Dockerfile as usual.

Docker. How to get bash\ssh inside runned container (run -d)?

I want to ssh or bash into runned docker container. Please, see example:
$ sudo docker run -d webserver
webserver is clean image from ubuntu:14.04
$ sudo docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
665b4a1e17b6 webserver:latest /bin/bash ... ... 22/tcp, 80/tcp loving_heisenberg
now I want to get something like this (go into runned container):
$ sudo docker run -t -i webserver (or maybe 665b4a1e17b6 instead)
$ root#665b4a1e17b6:/#
Previously I used Vagrant so I want to get behavior similar to vagrant ssh. Please, could anyone help me?
After the release of Docker version 1.3, the correct way to get a shell or other process on a running container is using the docker exec command. For example, you would run the following to get a shell on a running container:
docker exec -it myContainer /bin/bash
You can find more information in the documentation.
The answer is docker attach command.
For information see: https://askubuntu.com/a/507009/159189

Docker: bash terminal starts without prompt

I have a simple container that looks like this:
FROM devbox/rails3.2.1
RUN apt-get install -y -q libmysql-ruby libmysqlclient-dev
RUN apt-get install -y -q libqtwebkit-dev
EXPOSE 3000
CMD /bin/bash
where devbox/rails3.2.1 is a container I made that starts with 'FROM ubuntu' and installs Ruby on Rails. This is a running in a Vagrant Virtual Box VM using Ubuntu 12.04.3 LTS. When I run this using:
docker run -t -i -name myapp -p 3000:3000 -v /src/myapp:/src/myapp -link myappsql:myappsql devbox/myapp
The container starts, but my terminal shows a blank line with no prompt and typing doesn't do anything. If I run docker ps I can see that the container is running. Even stranger, If I open a second terminal and run 'docker attach myapp' I get a functioning terminal (though I have to press enter first) and if I switch back to my first terminal and type, the output appears in my second terminal!
Any help much appreciated.
That all sounds like expected functionality.
When doing the "docker run" command put the "/bin/bash" in it to immediately have the bash available to you without having to attach first.
docker run -t -i -name myapp -p 3000:3000 -v /src/myapp:/src/myapp -link myappsql:myappsql devbox/myapp /bin/bash

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