How to enter in a Docker container already running with a new TTY

Question

I have a container that is running the Apache service in the foreground  I would like to be able to access the container from another shell in order to  poke around  inside it and examine the files  At the moment  if I attach to the container  I am left looking at the Apache daemon and cannot run any commands   Is it possible to attach another tty to a running container  Possibly  I can take advantage of the fact that Docker is actually just wrapping around LXC containers  I have tried sudo lxc-console -n  container-id  -t  1-4  but it appears that only one tty is made available and that is the one running the apache daemon  Perhaps there is a way to enable multiple lxc consoles during the build   I would rather not configure and build the container with an openssh service if possible

User · Answer

On Windows 10  I have docker installed  I am running Jnekins on a container and I encountered the same error message  Here is a step by step guide to resolve this issue     Step 1  Open gitbash and run docker run -p 8080 8080 -p 50000 50000 jenkins   Step 2  Open a new terminal    Step 3  Do  docker ps  to get list of the running container  Copy the container id   Step 4  Now if you do  docker exec -it  container id  sh  or  docker exec -it  container id  bash  you will get an error message similar to   the input device is not a TTY   If you are using mintty  try prefixing the command with  winpty    Step 5  Run command    winpty docker exec -it  container id  sh   vola    You are now inside the terminal

User · Answer

You should use J  r  me Petazzoni s tool called  nsenter  to enter a container without using SSH  See  https   github com jpetazzo nsenter  Install with simply running  docker run -v  usr local bin  target jpetazzo nsenter  Then use the command docker-enter  lt container-id gt  to enter the container

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What about running tmux GNU Screen within the container  Seems the smoother way to access as many vty as you want with a simple     docker attach  container id

User · Answer

With docker 1 3  there is a new command docker exec  This allows you to enter a running container  docker exec -it  container-id  bash

User · Answer

First step get container id   docker ps  This will show you something like     CONTAINER ID        IMAGE                                                                      COMMAND               CREATED             STATUS              PORTS                    NAMES      1170fe9e9460        localhost 5000 python env-7e847468c4d73a0f35e9c5164046ad88      run notebook sh    26 seconds ago      Up 25 seconds       0 0 0 0 8989- 9999 tcp   SLURM TASK-303337 0   1170fe9e9460 is the container id in this case   Second  enter the docker    docker exec -it  container id  bash  so in the above case  docker exec -it 1170fe9e9460 bash

User · Answer

docker exec -ti  CONTAINER NAME  sh  or  docker exec -ti  CONTAINER ID  sh

User · Answer

Update  As of docker 0 9  for the steps below to now work  one now has to update the  etc default docker file with the  -e lxc  to the docker daemon startup option before restarting the daemon  I did this by rebooting the host       This is all because           it  docker 0 9  contains a new  engine driver  abstraction to make possible the use   of other API than LXC to start containers  It also provide a new   engine driver based on a new API library  libcontainer  which is able   to handle Control Groups without using LXC tools  The main issue is   that if you are relying on lxc-attach to perform actions on your   container  like starting a shell inside the container  which is   insanely useful for developpment environment      source  Please note that this will prevent the new host only networking optional feature of docker 0 11 from  working  and you will only see the loopback interface  bug report     It turns out that the solution to a different question was also the solution to this one         you can use docker ps -notrunc to get the full lxc container ID and   then use lxc-attach -n  lt container id gt  run bash in that container as   root    Update  You will soon need to use ps --no-trunc instead of ps -notrunc which is being deprecated    Find the full container ID   Enter the lxc attach command    Top shows my apache process running that docker started

User · Answer

I started powershell on a running microsoft iis  run as daemon  using   docker exec -it  lt nameOfContainer gt  powershell

User · Answer

The  nsinit  way is   install nsinit  git clone git github com dotcloud docker git cd docker make shell   from inside the container   go install github com dotcloud docker pkg libcontainer nsinit nsinit   from outside   docker cp id docker container  go bin nsinit  root    use it  cd  var lib docker execdriver native  lt container id gt   nsinit exec bash

User · Answer

docker exec -t -i container name  bin bash   Will take you to the containers console

User · Answer

nsenter does that  However I also needed to enter a container in a simple way and nsenter didn t suffice for my needs  It was buggy in some occasions  black screen plus -wd flag not working   Furthermore I wanted to login as a specific user and in a specific directory   I ended up making my own tool to enter containers  You can find it at  https   github com Pithikos docker-enter  Its usage is as easy as    docker-enter  -u  lt user gt    -d  lt directory gt    lt container ID gt

[docker] How to enter in a Docker container already running with a new TTY

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