I am executing the command docker exec for example:
docker exec reverse ls
The first time, it works. Then, it displays the result, but wait indefinitely. I don't understand why.
The entrypoint of the container's image is:
ENTRYPOINT service ssh restart && service nginx && /bin/bash
Hm... That's probably because your ENTRYPOINT is a little bit anti-pattern.
Normally, one Docker container will only handle one thing which calls PID=1, but you give it three things to do and especially service nginx. It might cause the container running unexpectedly.
Your command actually is:
service ssh restart && service nginx && /bin/bash ls
Look, it's wired. But there are some tips to check if you really running that container.
a) Remove your ENTRYPOINT on Dockerifle first.
b) Running a container with only /bin/bash CMD
c) docker exec -it [CONTAINER_ID] /bin/bash to enter the container and run the commands to verify if works.
Hope it helps you.
Could you let me know how to run insmod and /sbin/init in one CMD.
I wrote Dockerfile with one of bellow CMDs
CMD [ "insmod", "a_module.ko", "&&", "/sbin/init" ]
CMD insmod a_module.ko && /sbin/init
Then I run
docker run -p 8080:80 -p 4433:443 -it --rm -d --cap-add=ALL --privileged <image id>
It emit container ID, but the docker ps didn't show anything.
only second CMD could install a_module, but the process was not running.
Do you have any idea to run these two from one CMD?
EDIT
I would like to setup experimental environment in this container.
The /sbin/init is needed to run systemctl in docker.
insmod is not permitted from RUN even though it is from root. Currently it is done in container manually, but I would like to automate it
That's why insmod and /sbin/init are needed from CMD.
To run more than one command with CMD, you would use:
CMD ["/bin/bash", "-c", "command1 && command2"]
Why you would want to try and run the full operating system services in the container by running /sbin/init is another question. It is not normal practice to do so. Containers would normally run one application only. Depending on how the container is setup when run, you may not even be able to run all normal operating system services or commands.
Given the following Dockerfile:
From python:2.7-wheezy
RUN apt-get update && apt-get upgrade --assume-yes
RUN apt-get install mysql-server --assume-yes
ENTRYPOINT service mysql start
When I run the docker, it exits immediately after starting mysql server:
Jamess-iMac:docker-python-test jameslin$ docker run -i -t 9618f71f65e4 /bin/bash
[ ok ] Starting MySQL database server: mysqld ..
[info] Checking for tables which need an upgrade, are corrupt or were
not closed cleanly..
Jamess-iMac:docker-python-test jameslin$
How do I make it automatically start up mysql but stays in interactive mode?
ubuntu 12.04 into docker “service mysql start”
If you read above thread you can see that Docker doesn't have any runlevel so mysql doesn't know when it should start.
You can run two container and create a nework between them. One for mysql and another for pythonapp. Here is how you can create a network between two container
docker network create <network_name>
Start the container attaching the container to new network using --net=<network_name>
docker run -d --net=anetwork --name=mysql -e MYSQL_USER=ROOT -e MYSQL_ALLOW_EMPTY_PASSWORD=yes mysql
docker run --net=anetwork --name=pythonapp -it python:2.7-wheezy bash
I think you are confused between ENTRYPOINT and CMD. The key point to understand is that an ENTRYPOINT will always be run when the image is started, even if a command is supplied to the docker run invocation. If you try to supply a command, it will add that as an argument to the ENTRYPOINT, replacing the default defined in the CMD instruction. You can only override the ENTRYPOINT if you explicitly pass in an --entrypoint flag to the docker run command.
This means that running the image with a /bin/bash command will not give you a shell; rather it will supply /bin/bash as an argument to the service mysql start.
Network between container
ubuntu 12.04 into docker “service mysql start”
Difference Between CMD and ENTRYPOINT in Dockerfile
Your ENTRYPOINT / CMD directive needs to be a long running command. service mysql start is not a continuous command as it runs, in Ubuntu, the service itself and then the command exits.
To make this simple - if you're just trying to run a mysql container you can run docker run mysql. If you absolutely need to run a one-off mysql container you can piggy-back off of the way that the default mysql container starts here: MySql Dockerfile - CMD ["mysqld"] - which should be similar to what you see as the actual start command in /etc/init.d/mysql
I end my Debian Dockerfile with these lines:
EXPOSE 80 22
COPY etc/supervisor/conf.d /etc/supervisor/conf.d
CMD ["/usr/bin/supervisord", "-c", "/etc/supervisor/supervisord.conf"]
In /etc/supervisor/conf.d/start.conf file:
[program:ssh]
command=/usr/sbin/service ssh restart
[program:nginx]
command=/usr/sbin/nginx -g 'daemon off;'
[program:systemctl]
command=/bin/systemctl daemon-reload
[program:systemctl]
command=/bin/systemctl start php7-fpm.service
If I try to run this Docker image with the following command:
$ docker run -d -p 8080:80 -p 8081:22 lanti/debian
It's immediately stops running. if I try to run it on the foreground:
$ docker run -it -v /home/core/share:/root/share -p 8080:80 -p 8081:22 lanti/debian
It's the same, immediate exit. If I run with bash CMD:
$ docker run --rm -it -v /home/core/share:/root/share -p 8080:80 -p 8081:22 lanti/debian bash
It stays active in the console, but the predefined commands by supervisor not run, so I need to run $ service supervisor restart inside the container, otherwise Nginx and SSH won't be started.
How I can start a docker container with multiple commands run at startup? In the past I used ExecStartPost lines in a systemd file under the host OS, but becouse of that, the systemd file became complex so I try to move the pre-start commands into the container, to run automatically at any type of startup.
This docker container will have nginx, php, ssh, phpmyadmin and mysql in the future. I don't want multiple containers.
Thank You for your help!
Lets preface this by saying running the kitchen sink in a docker container is not a best practice. Docker is not a virtual machine.
That said, a few problems.
just like the processes that supervisor controls, supervisor itself should NOT daemonize. Add -n
I'm not entirely sure why you expect, need, or want to have systemd and supervisor running. Most docker containers do not have a functioning init system. Why not just user supervisor for everything? Unless docker has significantly changed in the last couple versions, systemd inside the container will not work like you think it should.
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 :)