I try to start container with following command
sudo docker run ubuntu
after that I checked with
sudo docker ps -a
found the container exited already
why does it exit?
How could I keep it running in backgroud without specifying -it and attach to it on demanding?
Solved by myself, a elegant way to keep the container running and waiting for further "attach" or "exec" is the following (to keep the STDIN open by -i option)
docker run -i -d ubuntu
You need to start an application with the docker run command that won't exit.
Example:
docker run -d --entrypoint '/bin/bash cat' ubuntu
You can add the tail command while running the container.
docker run -d ubuntu tail -f /dev/null
the correct syntax is
(from docker run --help)
docker run [OPTIONS] IMAGE [COMMAND] [ARG...]
you have forgotten to specify a command.
You should have a look at the docker hub
https://registry.hub.docker.com/
For example for nginx, if you look at
https://hub.docker.com/_/nginx/
you will find
docker run --name some-nginx -v /some/nginx.conf:/etc/nginx/nginx.conf:ro -d nginx
If you look at
https://github.com/nginxinc/docker-nginx/blob/7f3ef0927ec619d20181e677c97f991df0d7d446/Dockerfile
you will notice that the last line of the Dockerfile is
CMD ["nginx", "-g", "daemon off;"]
This means that when you launch the docker image nginx, the implicit action is to start nginx.
If you want the container to not exist, you have to use the -d argument
So it look like this:
docker run -d ubuntu
Related
Why when i run the command
docker run ubuntu
without option '-it' is not possible to interact with the created container even when running command start with the -a -i options
docker start -a -i CONTAINER_ID
or when i run
docker start CONTAINER_ID
simply the container has the status "Exit (0) 4 seconds ago"
But when i run
docker run -it ubuntu
i can use bash shell of ubuntu using 'docker start -a -i'
When you run docker run without -it it's still running the container but you've not given it a command, so it finishes and exits.
If you try:
docker run ubuntu /bin/bash -c "echo 'hello'";
It'll run ubunu, then the command, and then finish because there is no reason for it to be kept alive afterwards.
-i is saying keep it alive and work within in the terminal (allow it to be interactive), but if you type exit, you're done and the container stops.
-t is showing the terminal of within the docker container (see: What are pseudo terminals (pty/tty)?)
-it allows you to see the terminal in the docker instance and interact with it.
Additionally you can use -d to run it in the background and then get to it afterwards.
Ex:
docker run -it -d --name mydocker ubuntu;
docker exec -it mydocker /bin/bash;
TLDR is -it allows you connect a terminal to interactively connect to the container.
If you run docker run --help, you can find the details about docker run options.
$ docker run --help
Usage: docker run [OPTIONS] IMAGE [COMMAND] [ARG...]
Run a command in a new container
Options:
...
-i, --interactive Keep STDIN open even if not attached
...
-t, --tty Allocate a pseudo-TTY
How can do something like:
docker exec -it 06a0076fb4c0 install-smt
But use the name of the container instead
docker exec -it container/container install-smt
I am running a build on CI server so I can not manually input the container ID.
How can I achieve this?
Yes, you can do this by naming the container with --name. Note that your command with container/container is likely referencing an image name and not the container.
➜ ~ docker run --name my_nginx -p 80:80 -d nginx
d122acc37d5bc2a5e03bdb836ca7b9c69670de79063db995bfd6f66b9addfcac
➜ ~ docker exec my_nginx hostname
d122acc37d5b
Although it won't save any typing, you can do something like this if you want to use the image name instead of giving the container a name:
docker run debian
docker exec -it `docker ps -q --filter ancestor=debian` bash
This will only work if you're only running one instance of the debian image.
It does help if you're constantly amending the image when working on a new Dockerfile, and wanting to repeatedly run the same command in each new container to check your changes worked as expected.
I was able to fix this by setting a container name in the docker-compose file, and rundocker exec -it with the name form the file.
#Héctor (tnx)
These steps worked for me:
This will start the container named mytapir and spawn a shell into the docker container:
docker run -d --name mytapir -it wsmoses/tapir-built:latest bash
Upon docker ps to ensure the docker container is running:
docker exec -it mytapir /bin/bash
Will spawned a shell into an existing container named mytapir.
And you can stop the container as usual docker stop mytapir.
And starting it via docker start mytapir, if it is not running.
(check via docker ps -a)
I'd like to install mysql server on a centos:6.6 container.
However, when I run docker run --name myDB -e MYSQL_ROOT_PASSWORD=my-secret-pw -d centos:6.6, I got docker: Error response from daemon: No command specified. error.
Checking the document from docker run --help, I found that the COMMAND seems to be an optional argument when executing docker run. This is because [COMMAND] is placed inside a pair of square brackets.
$ docker run --help
Usage: docker run [OPTIONS] IMAGE [COMMAND] [ARG...]
Run a command in a new container
I also find out that the official repository of mysql doesn't specify a command when starting a MySQL container:
Starting a MySQL instance is simple:
$ docker run --name some-mysql -e MYSQL_ROOT_PASSWORD=my-secret-pw -d mysql:tag
Why should I provide a command when running a centos:6.6 container, but not so when running a mysql container?
I'm guessing that maybe centos:6.6 is specially-configured so that the user must provide a command when running it.
if you use centos:6.6, you do need to provide a command when you issue "docker run" command.
The reason the officical repository of mysql does not specify a command is because it has CMD command in it's docker file: CMD ["mysqld"]. Check it's docker file here.
The CMD in docker file is the default command when run the container without a command.
You can read here to better understand what you can use in a docker file.
In your case, you can
Start your centos 6.6 container
Take official mysql docker file as reference, issue similar command (change apt-get to yum ( or sudo yum if you don't use the default root user)
Once you can successfully start mysql, you can put all your command in your docker file, just to make sure the first line is "From centos:6.6"
Build your image
Run a container with your image, then you don't need to provide a command in docker run
You can share your docker file in docker hub, so that other people can user yours.
good luck.
According to tutorial I read so far, use "docker run -d" will start a container from image, and the container will run in background. This is how it looks like, we can see we already have container id.
root#docker:/home/root# docker run -d centos
605e3928cdddb844526bab691af51d0c9262e0a1fc3d41de3f59be1a58e1bd1d
But if I ran "docker ps", nothing was returned.
So I tried "docker ps -a", I can see container already exited:
root#docker:/home/root# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
605e3928cddd centos:latest "/bin/bash" 31 minutes ago Exited (0) 31 minutes ago kickass_swartz
Anything I did wrong? How can I troubleshoot this issue?
The centos dockerfile has a default command bash.
That means, when run in background (-d), the shell exits immediately.
Update 2017
More recent versions of docker authorize to run a container both in detached mode and in foreground mode (-t, -i or -it)
In that case, you don't need any additional command and this is enough:
docker run -t -d centos
The bash will wait in the background.
That was initially reported in kalyani-chaudhari's answer and detailed in jersey bean's answer.
vonc#voncvb:~$ d ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
4a50fd9e9189 centos "/bin/bash" 8 seconds ago Up 2 seconds wonderful_wright
Note that for alpine, Marinos An reports in the comments:
docker run -t -d alpine/git does not keep the process up.
Had to do: docker run --entrypoint "/bin/sh" -it alpine/git
Original answer (2015)
As mentioned in this article:
Instead of running with docker run -i -t image your-command, using -d is recommended because you can run your container with just one command and you don’t need to detach terminal of container by hitting Ctrl + P + Q.
However, there is a problem with -d option. Your container immediately stops unless the commands keep running in foreground.
Docker requires your command to keep running in the foreground. Otherwise, it thinks that your applications stops and shutdown the container.
The problem is that some application does not run in the foreground. How can we make it easier?
In this situation, you can add tail -f /dev/null to your command.
By doing this, even if your main command runs in the background, your container doesn’t stop because tail is keep running in the foreground.
So this would work:
docker run -d centos tail -f /dev/null
Or in Dockerfile:
ENTRYPOINT ["tail"]
CMD ["-f","/dev/null"]
A docker ps would show the centos container still running.
From there, you can attach to it or detach from it (or docker exec some commands).
According to this answer, adding the -t flag will prevent the container from exiting when running in the background. You can then use docker exec -i -t <image> /bin/bash to get into a shell prompt.
docker run -t -d <image> <command>
It seems that the -t option isn't documented very well, though the help says that it "allocates a pseudo-TTY."
Background
A Docker container runs a process (the "command" or "entrypoint") that keeps it alive. The container will continue to run as long as the command continues to run.
In your case, the command (/bin/bash, by default, on centos:latest) is exiting immediately (as bash does when it's not connected to a terminal and has nothing to run).
Normally, when you run a container in daemon mode (with -d), the container is running some sort of daemon process (like httpd). In this case, as long as the httpd daemon is running, the container will remain alive.
What you appear to be trying to do is to keep the container alive without a daemon process running inside the container. This is somewhat strange (because the container isn't doing anything useful until you interact with it, perhaps with docker exec), but there are certain cases where it might make sense to do something like this.
(Did you mean to get to a bash prompt inside the container? That's easy! docker run -it centos:latest)
Solution
A simple way to keep a container alive in daemon mode indefinitely is to run sleep infinity as the container's command. This does not rely doing strange things like allocating a TTY in daemon mode. Although it does rely on doing strange things like using sleep as your primary command.
$ docker run -d centos:latest sleep infinity
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
d651c7a9e0ad centos:latest "sleep infinity" 2 seconds ago Up 2 seconds nervous_visvesvaraya
Alternative Solution
As indicated by cjsimon, the -t option allocates a "pseudo-tty". This tricks bash into continuing to run indefinitely because it thinks it is connected to an interactive TTY (even though you have no way to interact with that particular TTY if you don't pass -i). Anyway, this should do the trick too:
$ docker run -t -d centos:latest
Not 100% sure whether -t will produce other weird interactions; maybe leave a comment below if it does.
Hi this issue is because docker containers exit if there is no running application in the container.
-d
option is just to run a container in deamon mode.
So the trick to make your container continuously running is point to a shell file in docker which will keep your application running.You can try with a start.sh file
Eg: docker run -d centos sh /yourlocation/start.sh
This start.sh should point to a never ending application.
In case if you dont want any application to be running,you can install monit which will keep your docker container running.
Please let us know if these two cases worked for you to keep your container running.
All the best
You can accomplish what you want with either:
docker run -t -d <image-name>
or
docker run -i -d <image-name>
or
docker run -it -d <image-name>
The command parameter as suggested by other answers (i.e. tail -f /dev/null) is completely optional, and is NOT required to get your container to stay running in the background.
Also note the Docker documentation suggests that combining -i and -t options will cause it to behave like a shell.
See:
https://docs.docker.com/engine/reference/run/#foreground
I have this code snippet run from the ENTRYPOINT in my docker file:
while true
do
echo "Press [CTRL+C] to stop.."
sleep 1
done
Run the built docker image as:
docker run -td <image name>
Log in to the container shell:
docker exec -it <container id> /bin/bash
execute command as follows :
docker run -t -d <image-name>
if you want to specify port then command as below:
docker run -t -d -p <port-no> <image-name>
verify the running container using following command:
docker ps
Docker container exits if task inside is done, so if you want to keep it alive even if it does not have any job or already finished them, you can do docker run -di image. After you do docker container ls you will see it running.
Docker requires your command to keep running in the foreground. Otherwise, it thinks that your applications stops and shutdown the container.
So if your docker entry script is a background process like following:
/usr/local/bin/confd -interval=30 -backend etcd -node $CONFIG_CENTER &
The '&' makes the container stop and exit if there are no other foreground process triggered later.
So the solution is just remove the '&' or have another foreground CMD running after it, such as
tail -f server.log
If you are using CMD at the end of your Dockerfile, what you can do is adding the code at the end. This will only work if your docker is built on ubuntu, or any OS that can use bash.
&& /bin/bash
Briefly the end of your Dockerfile will look like something like this.
...
CMD ls && ... && /bin/bash
So if you have anything running automatically after you run your docker image, and when the task is complete the bash terminal will be active inside your docker. Thereby, you can enter you shell commands.
Maybe it is just me but on CentOS 7.3.1611 and Docker 1.12.6 but I ended up having to use a combination of the answers posted by #VonC & #Christopher Simon to get this working reliably. Nothing I did before this would stop the container from exiting after it ran CMD successfully. I am starting oracle-xe-11Gr2 and sshd.
Dockerfile
...
RUN ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key -N '' && systemctl enable sshd
...
CMD /etc/init.d/oracle-xe start && /sbin/sshd && tail -f /dev/null
Then adding -d -t and -i to run
docker run --shm-size=2g --name oracle-db -d -t -i -p 5022:22 -p 5080:8080 -p 1521:1521 centos-oracle:7.3.1611
Finally after hours of bashing my head against the wall
ssh -v root#127.0.0.1 -p 5022
...
root#127.0.0.1's password:
debug1: Authentication succeeded (password).
For whatever reason the above will exit after executing CMD if the tail -f is removed, or any of the -t -d -i options are omitted.
I had the same issue, just opening another terminal with a bash on it worked for me :
create container:
docker run -d mcr.microsoft.com/mssql/server:2019-CTP3.0-ubuntu
containerid=52bbc9b30557
start container:
docker start 52bbc9b30557
start bash to keep container running:
docker exec -it 52bbc9b30557 bash
start process you need:
docker exec -it 52bbc9b30557 /path_to_cool_your_app
Running docker with interactive mode might solve the issue.
Here is the example for running image with and without interactive mode
chaitra#RSK-IND-BLR-L06:~/dockers$ sudo docker run -d -t -i test_again1.0
b6b9a942a79b1243bada59db19c7999cfff52d0a8744542fa843c95354966a18
chaitra#RSK-IND-BLR-L06:~/dockers$ sudo docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
chaitra#RSK-IND-BLR-L06:~/dockers$ sudo docker run -d -t -i test_again1.0 bash
c3d6a9529fd70c5b2dc2d7e90fe662d19c6dad8549e9c812fb2b7ce2105d7ff5
chaitra#RSK-IND-BLR-L06:~/dockers$ sudo docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
c3d6a9529fd7 test_again1.0 "bash" 2 seconds ago Up 1 second awesome_haibt
You can simply use:
docker container run -d -it <container name or id> /bin/bash
I have explained it in the following post that has the same question.
How to retain docker alpine container after "exit" is used?
I was also facing the same problem but in a different manner. When I create the docker containers. it automatically stops the unused containers which are just running in the background. Sometimes it also stops the containers that are in the use.
In my situation, this is because of the permission of the docker.sock files it earlier has.
what you have to do is :-
Install docker again.(As i work on ubuntu i install it from here)
Run the command to change the permissions.
sudo chmod 666 /var/run/docker.sock
Install docker-compose (this is optional as I have compose file to create many containers together)
sudo curl -L "https://github.com/docker/compose/releases/download/1.26.0/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
sudo chmod +x /usr/local/bin/docker-compose
check for the version to ensure that I have the latest one and not get problem with some deprications.
Then I run the docker container build.
Argument order matters
Jersey Beans answer (all 3 examples) worked for me. After quite a bit of trial and error I realized that the order of the arguments matter.
Keeps the container running in the background:
docker run -t -d <image-name>
Keeps the container running in the foreground: docker run <image-name> -t -d
It wasn't obvious to me coming from a Powershell background.
if you want to operate on the container, you need to run it in foreground to keep it alive.
There are multiple options out there to run the container in foreground/detached state. But if you still feel the issue is not resolved, you can try troubleshooting the issue by viewing the logs.
sudo docker logs -f >> container.log
additionally you can also use --details to show extra details provided to logs.
Incorrect Path to App in Dockerfile:
I was migrating an application from a RHEL server to a Docker container using Alpine Linux.
No errors during the build, so I was surprised to see the container immediately exit!
First port of call:
docker logs <containerID>
This revealed the path of the binary I had supplied to CMD in the Dockerfile was bogus:
line 0: /sbin/postfix: not found
Well that told me how things were broken, but not specifically where: I still required the correct path for the binary in Alpine Linux...
Troubleshooting:
Googling didn't reveal the correct path to it, so I added the following line to my Dockerfile:
RUN which postfix
I then reviewed my build logging- provided by the below command appended to my build command- to retrieve the value of RUN which postfix
--progress=plain > /path/to/build.log 2>&1
The Fix:
I deleted this test build, supplied the correct path- /usr/sbin/postfix - to CMD in the Dockerfile, deleted RUN which postfix and ran another build.
Voila; the process now remained up.
So a duff path was causing the container to immediately exit...
These 4 commands all work to keep your docker container running:
docker run -td centos
docker run -dt centos
docker run -t -d centos
docker run -d -t centos
Firstly, You need to check if any container is running
Type command,
docker ps -all
If any container is running then stop them
Type command,
docker stop Container Id
Now, Finally run the docker by using below command..........
docker run -t -p 2020:3000 dockerImageName
Hence, Open your google chrome and visit on localhost:2020
Congrats :)
I created a container with -d so it's not interactive.
docker run -d shykes/pybuilder bin/bash
I see that the container has exited:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
d6c45e8cc5f0 shykes/pybuilder:latest "bin/bash" 41 minutes ago Exited (0) 2 seconds ago clever_bardeen
Now I would like to run occasional commands on the machine and exit. Just to get the response.
I tried to start the machine. I tried attaching. I thought I could call run with a container, but that does not seem to be allowed. Using start just seems to run and then exist quickly.
I'd like to get back into interactive mode after exiting.
I tried:
docker attach d6c45e8cc5f0
But I get:
2014/10/01 22:33:34 You cannot attach to a stopped container, start it first
But if I start it, it exits anyway. Catch 22. I can't win.
In October 2014 the Docker team introduced docker exec command: https://docs.docker.com/engine/reference/commandline/exec/
So now you can run any command in a running container just knowing its ID (or name):
docker exec -it <container_id_or_name> echo "Hello from container!"
Note that exec command works only on already running container. If the container is currently stopped, you need to first run it with the following command:
docker run -it -d shykes/pybuilder /bin/bash
The most important thing here is the -d option, which stands for detached. It means that the command you initially provided to the container (/bin/bash) will be run in the background and the container will not stop immediately.
Your container will exit as the command you gave it will end. Use the following options to keep it live:
-i Keep STDIN open even if not attached.
-t Allocate a pseudo-TTY.
So your new run command is:
docker run -it -d shykes/pybuilder bin/bash
If you would like to attach to an already running container:
docker exec -it CONTAINER_ID /bin/bash
In these examples /bin/bash is used as the command.
So I think the answer is simpler than many misleading answers above.
To start an existing container which is stopped
docker start <container-name/ID>
To stop a running container
docker stop <container-name/ID>
Then to login to the interactive shell of a container
docker exec -it <container-name/ID> bash
To start an existing container and attach to it in one command
docker start -ai <container-name/ID>
Beware, this will stop the container on exit. But in general, you need to start the container, attach and stop it after you are done.
To expand on katrmr's answer, if the container is stopped and can't be started due to an error, you'll need to commit it to an image. Then you can launch bash in the new image:
docker commit [CONTAINER_ID] temporary_image
docker run --entrypoint=bash -it temporary_image
Some of the answers here are misleading because they concern containers that are running, not stopped.
Sven Dowideit explained on the Docker forum that containers are bound to their process (and Docker can't change the process of a stopped container, seemingly due at least to its internal structure: https://github.com/docker/docker/issues/1437). So, basically the only option is to commit the container to an image and run it with a different command.
See https://forums.docker.com/t/run-command-in-stopped-container/343
(I believe the "ENTRYPOINT with arguments" approach wouldn't work either, since you still wouldn't be able to change the arguments to a stopped container.)
I had to use bash -c to run my command:
docker exec -it CONTAINER_ID bash -c "mysql_tzinfo_to_sql /usr/share/zoneinfo | mysql mysql"
Creating a container and sending commands to it, one by one:
docker create --name=my_new_container -it ubuntu
docker start my_new_container
// ps -a says 'Up X seconds'
docker exec my_new_container /path/to/my/command
// ps -a still says 'Up X+Y seconds'
docker exec my_new_container /path/to/another/command
If you are trying to run shell script, you need run it as bash.
docker exec -it containerid bash -c /path/to/your/script.sh
This is a combined answer I made up using the CDR LDN answer above and the answer I found here.
The following example starts an Arch Linux container from an image, and then installs git on that container using the pacman tool:
sudo docker run -it -d archlinux /bin/bash
sudo docker ps -l
sudo docker exec -it [container_ID] script /dev/null -c "pacman -S git --noconfirm"
That is all.
Pipe a command to docker exec bash stdin
Must remove the -t for it to work:
echo 'touch myfile' | docker exec -i CONTAINER_NAME bash
This can be more convenient that using CLI options sometimes.
Tested with:
docker run --name ub16 -it ubuntu:16.04 bash
then on another shell:
echo 'touch myfile' | docker exec -i ub16 bash
Then on first shell:
ls -l myfile
Tested on Docker 1.13.1, Ubuntu 16.04 host.
I would like to note that the top answer is a little misleading.
The issue with executing docker run is that a new container is created every time. However, there are cases where we would like to revisit old containers or not take up space with new containers.
(Given clever_bardeen is the name of the container created...)
In OP's case, make sure the docker image is first running by executing the following command:
docker start clever_bardeen
Then, execute the docker container using the following command:
docker exec -it clever_bardeen /bin/bash
I usually use this:
docker exec -it my-container-name bash
to continuously interact with a running container.
Assuming the image is using the default entrypoint /bin/sh -c, running /bin/bash will exit immediately in daemon mode (-d). If you want this container to run an interactive shell, use -it instead of -d. If you want to execute arbitrary commands in a container usually executing another process, you might want to try nsenter or nsinit. Have a look at https://blog.codecentric.de/en/2014/07/enter-docker-container/ for the details.
Unfortunately it is impossible to override ENTRYPOINT with arguments with docker run --entrypoint to achieve this goal.
Note: you can override the ENTRYPOINT setting using --entrypoint, but
this can only set the binary to exec (no sh -c will be used).
For Mac:
$ docker exec -it <container-name> sh
if you want to connect as root user:
$ docker exec -u 0 -it <container-name> sh
Simple answer: start and attach at the same time. In this case you are doing exactly what you asked for.
docker start <CONTAINER_ID/CONTAINER_NAME> && docker attach <CONTAINER_ID/CONTAINER_NAME>
make sure to change <CONTAINER_ID/CONTAINER_NAME>
I am running windows container and I need to look inside the docker container for files and folder created and copied.
In order to do that I used following docker entrypoint command to get the command prompt running inside the container or attach to the container.
ENTRYPOINT ["C:\\Windows\\System32\\cmd.exe", "-D", "FOREGROUND"]
That helped me both to the command prompt attach to container and to keep the container a live. :)
# docker exec -d container_id command
Ex:
# docker exec -d xcdefrdtt service jira stop
A quick way to resume and access the most recently exited container:
docker start -a -i `docker ps -q -l`
An easy solution that solved a similar problem for me:
docker run --interactive --tty <name_of_image>