Is it possible to start a shell session in a running container (without ssh)

Question

I was naively expecting this command to run a bash shell in a running container :

docker run \"id of running container\" /bin/bash

it look

Answer 1

Here's my solution

In the Dockerfile:

# ...
RUN mkdir -p /opt
ADD initd.sh /opt/
RUN chmod +x /opt/initd.sh
ENTRYPOINT ["/opt/initd.sh"]

In the initd.sh file

#!/bin/bash
...
/etc/init.d/gearman-job-server start
/etc/init.d/supervisor start
#very important!!!
/bin/bash

After image is built you have two options using exec or attach:

1. Use exec (preferred) and run:

   docker run --name $CONTAINER_NAME -dt $IMAGE_NAME
   

   then

   docker exec -it $CONTAINER_NAME /bin/bash
   

   and use CTRL + D to detach

2. Use attach and run:

   docker run --name $CONTAINER_NAME -dit $IMAGE_NAME
   

   then

   docker attach $CONTAINER_NAME
   

   and use CTRL + P and CTRL + Q to detach

   Note: The difference between options is in parameter -i