Docker logging to container - docker

Question

I'm fresh user of Docker. The fist problem with which I'm faced is logging into container.
I'm found solutions to execute container bash commands by
docker exec -it ID bash
But, this is solution only for install/ remove packages. What to use if I want to edit nginx config in docker container ?
One of solutions can be loggin to container via ssh connection, but maybe Docker have something own for this ?, I mean easilly access without install OpenSSH ?

Answer 1

as you said,
docker exec -it container_id bash
and then use your favorite editor to edit any nginx config file. vi or nano is usually installed, but you may need to install emacs or vim, if this is your favorite editor
if you have just a few characters to modify,
docker exec container_id sed ...
might do the job. If you want to SSH into your container, you will need to install SSH and deal with the SSH keys, I am not sure this is what you need.

Answer 2

You're going about it the wrong way. You should rarely need to log into a container to edit files.
Instead, mount the nginx.conf with -v from the host. That way you can edit the file with your normal editor. Once you've got the config working the way you want it, you can then build a new image with it baked in.
In general, you have to get into the mindset of containers being ephemeral. You don't patch them; you throw them away and replace them with a fixed version.

Answer 3

How: Docker logging to container
Yes, you can. You can login the running container.
Exist docker exec or docker attach is not good enough. Looking to start a shell inside a Docker container? The solution is: jpetazzo/nsenter with two commands: nsenter and docker-enter.
If you are in Linux environment, then run below command:
docker run --rm -v /usr/local/bin:/target jpetazzo/nsenter
docker ps
# replace <container_name_or_ID> with real container name or ID.
PID=$(docker inspect --format {{.State.Pid}} <container_name_or_ID>)
nsenter --target $PID --mount --uts --ipc --net --pid
Then you are in that running container, you can run any linux commands now.
I prefer the other command docker-enter. Without login the container, you can directly run linux commands in container with docker-enter command. Second, I can't memory multiple options of nsenter command and no need to find out the container's PID.
docker-enter 0e8c248982c5 ls /opt
If you are mac or windows user, run docket with toolbox:
docker-machine ssh default
docker run --rm -v /usr/local/bin:/target jpetazzo/nsenter
PID=$(docker inspect --format {{.State.Pid}} 0e8c248982c5)
sudo nsenter --target $PID --mount --uts --ipc --net --pid
If you are mac or windows user, run docket with boot2docker:
boot2docker ssh
docker run --rm -v /usr/local/bin:/target jpetazzo/nsenter
PID=$(docker inspect --format {{.State.Pid}} 0e8c248982c5)
sudo nsenter --target $PID --mount --uts --ipc --net --pid
Note: The command docker run --rm -v /usr/local/bin:/target jpetazzo/nsenter only need run one time.
How: edit nginx config
For your second question, you can think about ONBUILD in Docker.
ONBUILD COPY nginx.conf /etc/nginx/nginx.conf
With this solution, you can:
edit nginx.conf in local, you can use any exist editor .
needn't build your image every time after you change nginx configuration.
every time, after you change nginx.conf file in local, you need stop, remove and re-run the containe, new nginx.conf file will be deployed into contrainer when docker run command.
You can refer the detail on how to use ONBUILD here: docker build