Docker container will automatically stop after “do

Question

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?

Answer 1

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

Answer 2

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

---

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 are not running on 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

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).

Answer 3

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

Answer 4

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.

Answer 5

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.

Answer 6

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