Docker Commit

AlyRagab

Hi All,

In Docker , there is an issue i have that when i pull an image like the below command

docker pull centos

then i will be in need to run it to create a Container

docker run -it centos /bin/bash

the issue here is if i return back to the docker host any changes will not be saved into that container and the solution for that is to use the " docker commit " command
that command will create another instance of that image again and thus will take another space in the storage

so is there any advice to solve such thing ?

Thanks

AlyRagab

Is there any advice about this issue ?.

aidan_walsh

What changes are you talking about? App updates? Data?

AlyRagab

@aidan_walsh yes , any command executed or installed packages and so on.

aidan_walsh

Docker won't create a new, full image of the container when you run the commit command. It uses union mounted file systems to minimise the overhead. Running commit is probably the best thing for you to do.

Otherwise, perhaps application data should be stored in a volume?

AlyRagab

@aidan_walsh When i logged into the container by

docker run -it centos /bin/bash

and install the apache , then i logged out
when i tried to log in again i did not find the apache installed so why ?

aidan_walsh

@AlyRagab docker run creates a new container and starts it. I think you're looking for the docker start command.

AlyRagab

@aidan_walsh i think it can be done through

docker exec -it CONTAINER_NAME /bin/bash

i did it and installed the httpd package and when i exit and return to it again the apache is still installed.

aidan_walsh

@AlyRagab exec runs against a started container.

I think I'm not following the flow that you're using. Could you post all the commands you run when you experience the issue?

Emad R

@AlyRagab said in Docker Commit:

any advice to solve such thing ?
Thanks

My advice is to manage Docker from web interface UI, their you can see more of what docker is doing, and very helpful for new docker starters.

Launch or Install Docker UI on port 9000

docker pull uifd/ui-for-docker
docker run -d -p 9000:9000 --privileged -v /var/run/docker.sock:/var/run/docker.sock uifd/ui-for-docker

Then navigate from web browser to http://docker IP:9000

Also I think the issue is that when you exit centos, you exit via ctrl-c thus you end the session all together, what you want to do is run the centos as backrgound, and you can connect to it using another ssh client like putty or even from docker via connect:

Connect to an running Container

docker exec -it Ubuntu_1 bash
or
docker exec -it 7e153095b94f bash

AlyRagab

@msff-amman-Itofficer said in Docker Commit:

@AlyRagab said in Docker Commit:

any advice to solve such thing ?
Thanks

My advice is to manage Docker from web interface UI, their you can see more of what docker is doing, and very helpful for new docker starters.

Launch or Install Docker UI on port 9000

docker pull uifd/ui-for-docker
docker run -d -p 9000:9000 --privileged -v /var/run/docker.sock:/var/run/docker.sock uifd/ui-for-docker

Then navigate from web browser to http://docker IP:9000

Also I think the issue is that when you exit centos, you exit via ctrl-c thus you end the session all together, what you want to do is run the centos as backrgound, and you can connect to it using another ssh client like putty or even from docker via connect:

Connect to an running Container

docker exec -it Ubuntu_1 bash
or
docker exec -it 7e153095b94f bash

Yes , i will try test everything the Web UI offers , i am now working with the docker exec command.

but another question is do you prefer working with the supervisord or running each process in a separate container ?.

Emad R

@AlyRagab

The web UI benefit is that it allowed me to understand why everytime I launch container it spawned a new one and made new generic name for it, and helped me understand more visually.

However You can do much more from it, than stop/start/restart/commit containers, and monitoring them. When it comes to doing edits its advised you do everything from command.

I actually never heard of supervisord until you mentioned it, thus I ran the default which I reckon is each process in a separate container and never had any issues yet.

For me the important thing I learned exploring docker is distinction between application containers and OS containers, and how to approach each.

Since you mentioned centos in docker, you might want to check Alpine Linux images, cause they fit the Just enough OS ideology of docker (or was that VMware Photon).