I have Dockefile
FROM centos:7
So I have no entrypoint in dockerfile.
Then I build it to image
sudo docker build -t my_container .
Then I start it.
sudo docker run -t my_container
And I get open tty to container
root#my_container_id/
If I start it without -t it stopped immidiately after start.
How can I run docker container without start tty and without entrypoint?
You can start your container in a detached mode:
docker run -it -d my_container
The -d option here means your container will run in "detached" mode, in the background.
If you want to attach the container and drop to a shell, you can use:
docker exec -it my_container /bin/bash
Note, if your container is based on an alpine image, you need to use sh, i.e.:
docker exec -it my_container /bin/sh
You can't do that. Your container lives if its main process is running, so you have to have a main process which is the process with PID 1 inside your container, and your container will be up if that process is running.
Related
I have created image with our application, after running the image i can see the docker containers are also created, when I am trying to getinto the docker container i am getting the below error, can you please help me here.
""""OCI runtime exec failed: exec failed: container_linux.go:349: starting container process caused "exec: "bash": executable file not found in $PATH": unknown""""
I have tried to execute all the below commands
docker run -it exec 962f5d99458c
docker run -it 962f5d99458c
docker exec -it 962f5d99458c /bin
docker exec -it 75f6cb44f9e1
docker run --rm -ti 962f5d99458c sh
docker run --rm -ti 962f5d99458c /bin
docker exec --rm -ti 962f5d99458c /bin
docker exec -ti 962f5d99458c /bin
docker exec -ti 962f5d99458c \bin
docker exec -it 75f6cb44f9e1 bash
but no luck..... can you please help me here.
What the error says is that the startup command is invalid because the image has no (or it's not on $PATH) certain executable in it (bash in this case). The absence of bash is adequate for certain images (e.g. based on Alpine Linux or scratch) but if there is any shell at all, you can use sh:
# create a container from image and get straight into shell
docker run -it <image> sh
# or start a container in background, then get into shell
docker run -d <image>
docker exec -it <container> sh
If the image has no shell in it, then the only way to launch it, is by using the binary of the application the image supposed to run. Normally it works out of the box, unless you've overridden ENTRYPOINT and/or CMD in Dockerfile or by run arguments. The default startup arguments can be found with docker inspect:
docker image inspect nginx | jq '.[0].Config.Entrypoint'
docker image inspect nginx | jq '.[0].Config.Cmd'
In case you absolutely sure that the executable is there but still get the error, using an absolute path might help (e.g. /bin/bash instead of simply bash).
I'm running a docker container in detached mode, and I'm having difficulty running a command that's in the container's ~/.bashrc.
Inside the docker container's ~/.bashrc:
labserve () {
jupyter lab --ip=0.0.0.0 --allow-root --no-browser --NotebookApp.token=''
}
If I start the container with
$ docker run -d image -p 8888:8888 --name jupyterbox
I'd like to be able to tell the image to tell the detached container to open up jupyterlab with the following command:
$ docker exec jupyterbox bash -c labserve
however, when I do that, I get the error
bash: labinit: command not found
On the other hand, if I do
$ docker run -it jupyterbox bash
root#4e344655fc31:/home# labserve
The command runs correctly, and opens up a jupyterlab within my docker container running on port 8888.
How do I exec this command in a detached container?
I've created a dockerfile with various compile and build tools. The goal of the dockerimage is to standardize our development tools, and make it easy and consistent for developing.
Everything is installed.
What I am stuck on, is how to make the docker container keep running, and be able to have a bash shell to that container so that I can run, for example, make etc. ?
If I use ENTRYPOINT /bin/bash my container exits immediately. How to keep the container running?
You should use the command at run time. You run your Docker container in interatice mode (-i) and set the command to "/bin/bash":
docker run -it myDockerImage myCommandToExecuteInteractively
For instance:
docker run -it myDocker /bin/bash
Here is a real life example:
a) Pulling the most basic image
docker pull debian:jessie-slim
b) Let's have a bash there:
docker run -it debian:jessie-slim /bin/bash
c) Enjoy:
A docker container will run as long as the CMD/Entrypoint from your Dockerfile takes.
You can run your Docker container in interactive mode using switch i
sudo docker run -it --entrypoint=/bin/bash <imagename>
Example : docker run -it --entrypoint=/bin/bash ubuntu:14.04
This will start an interactive shell in your container. Your container will exit as soon as you exit that shell.
In my development, I find myself issuing a docker run command followed by a docker exec command on the resulting container ID quite frequently. It's a little annoying to have to copy/paste the container ID between commands, so I was trying to pipe the container ID into my docker exec command.
Here's my example command.
docker run -itd image | xargs -i docker exec -it {} bash
This starts the container, but then I get the following error.
the input device is not a TTY
Does anyone have any idea how to get around this?
Edit: I also forgot to mention I have an ENTRYPOINT defined and cannot override that.
Do this instead:
ID=$(docker run -itd image) && docker exec -it $ID bash
Because xargs executes it arguments without allocating a new tty.
If you just want to "bash"-into the container you do not have to pass the container-id around. You can simply run
docker run -it --rm <image> /bin/bash
For example, if we take the ubuntu base image
docker run -it --rm ubuntu /bin/bash
root#f80f83eec0d4:/#
from the documentation
-t : Allocate a pseudo-tty
-i : Keep STDIN open even if not attached
--rm : Automatically remove the container when it exits
The command /bin/bash overwrites the default command that is specified with the CMD instruction in the Dockerfile.
The answers from this question do not work.
The docker container always exits before I can attach or won't accept the -t flag. I could list all of the commands I've tried, but it's a combination of start exec attach with various -it flags and /bin/bash.
How do I start an existing container into bash? Why is this so difficult? Is this an "improper" use of Docker?
EDITS:
I created the container with docker run ubuntu. The information about the container: 60b93bda690f ubuntu "/bin/bash" About an hour ago Exited (0) 50 minutes ago ecstatic_euclid
First of all, a container is not a virtual machine. A container is an isolation environment for running a process. The life-cycle of the container is bound to the process running inside it. When the process exits, the container also exits, and the isolation environment is gone. The meaning of "attach to container" or "enter an container" actually means you go inside the isolation environment of the running process, so if your process has been exited, your container has also been exited, thus there's no container for you to attach or enter. So the command of docker attach, docker exec are target at running container.
Which process will be started when you docker run is configured in a Dockerfile and built into a docker image. Take image ubuntu as an example, if you run docker inspect ubuntu, you'll find the following configs in the output:
"Cmd": ["/bin/bash"]
which means the process got started when you run docker run ubuntu is /bin/bash, but you're not in an interactive mode and does not allocate a tty to it, so the process exited immediately and the container exited. That's why you have no way to enter the container again.
To start a container and enter bash, just try:
docker run -it ubuntu
Then you'll be brought into the container shell. If you open another terminal and docker ps, you'll find the container is running and you can docker attach to it or docker exec -it <container_id> bash to enter it again.
You can also refer to this link for more info.
Here is a very simple Dockerfile with instructions as comments ... launch it to spin up a running container you can exec login to
FROM ubuntu:20.04
ENV TERM linux
ENV DEBIAN_FRONTEND noninteractive
RUN apt-get update
RUN apt-get install -y
CMD ["/bin/bash"]
# ... save this file as Dockerfile then in same dir issue following
#
# docker build --tag stens_ubuntu . # creates image stens_ubuntu
#
# docker run -d stens_ubuntu sleep infinity # launches container
#
# docker ps # show running containers
#
#
# ... find CONTAINER ID from above and put into something like this
#
# docker exec -ti $( docker ps | grep stens_ubuntu | cut -d' ' -f1 ) bash # login to running container
# docker exec -ti 3cea1993ed28 bash # login to running container using sample containerId
#
A container will exit normally when it has no work to do ... if you give it no work it will exit immediately upon launch for this reason ... typically the last command of your Dockerfile is the execution of some flavor of a server which stays alive due to an internal event loop and in so doing keeps alive its enclosing container ... short of that you can mention a server executable which has been installed into the container as the final parameter of your call to
docker run -d my-image-name my-server-executable