06-docker-container.md

Docker Container

Let try to pull the busybox image, run the container by executing shell command in one shot:

docker run -it busybox sh

This docker run format can be broken down into two parts:

1. docker run [options]
2. [image] [command]

• options -it means we want to keep STDIN open even if not attached and allocate a pseudo-TTY
• image we are using container busybox image
• command running the sh command

To verify the container is running, type the following command from the new terminal:

docker ps

And you will see a similar response like this:

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
30b97ee57158        busybox             "sh"                7 seconds ago       Up 6 seconds                            charming_jones

Go back to the previous terminal and exit shell environment by running:

exit

Now verify the container again, you will see no container is currently running now:

docker ps

Instead, the container still exists with the Exited status; you can verify it by running:

docker ps -a

It will show a similar result:

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS                     PORTS               NAMES
30b97ee57158        busybox             "sh"                12 minutes ago      Exited (0) 9 minutes ago                       charming_jones

You can remove container by typing:

docker rm 30b97ee57158

If you want container automatically remove itself after the container in exited status. You can specify --rm options when executing the docker run command:

docker run -it --rm busybox sh

Also, instead of creating a container for executing the program, we can use docker exec to running the program in the current container:

# Check container id  from existing running containers
docker ps

# Return the result similar as following
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
a843b66bebbe        busybox             "sh"                4 seconds ago       Up 4 seconds                            pensive_carson

# Execute the program using the current container
docker exec -it a843b66bebbe sh

Next: Dockerfile