Docker - The Improved Commands

I just watched the very good, How to run Nginx inside Docker container video. In 9 minutes you will learn the basics of docker while starting up an nginx server running on docker. The real take away for me is the updated docker commands, which are finally as explicit as I always had wished they had been from the beginning. Like docker container run which was docker run.

Looking around the web, I found the commands had been updated already in 2017, see this blog post on the docker page. Again a case of "take more time to read the docs".

Some "New" Commands

docker container ls -a was docker ps -a
Listing all containers finally is named ls.

docker container stop was docker stop
Stopping a container is explicit. Would have made my learning curve less steep because I never knew if the command applied to an image or a container.

docker container logs was docker logs
Simply consistent.

docker container rm was docker rm
Remove a container. There is also docker image rm.

docker container --help
Just see them all.

Get Help

To get help for those commands use docker --help container <command>. I just struggled where to put the --help. Learned it now, will struggle less next time.

Also Have a Look at

As usual, inspecting the docs a bit more thoroughly I found commands I never looked at, but that are really valuable to know. Let me list a couple:

docker container top <container-name>

It shows the processes for a given container. I didn't figure out how to run that continuously, and not just once, like the native top command. Also the help is not really helping. The docs say: Display the running processes of a container

> docker container top site-stitcher        
PID                 USER                TIME                COMMAND
19933               root                0:00                {node} npm
19978               root                0:00                sh -c npm run build; npm run serve & ./build-on-file-change.sh
20141               root                0:00                {node} npm
20142               root                0:00                bash ./build-on-file-change.sh
20149               root                0:00                inotifywait --event modify,create,delete --monitor --recursive src content
20150               root                0:00                bash ./build-on-file-change.sh
20155               root                0:00                sh -c http-server _output -d -i --port 5000
20156               root                0:00                {node} http-server

docker container stats

The docs say: Display a live stream of container(s) resource usage statistics Which may look like this

> docker container stats
CONTAINER ID        NAME                CPU %               MEM USAGE / LIMIT     MEM %               NET I/O             BLOCK I/O           PIDS
d64cace6e8c9        site-stitcher       0.00%               35.41MiB / 1.944GiB   1.78%               16.3kB / 178kB      0B / 0B             38

docker container prune

Actually I needed it just last night, because I got lost in what was going on with my containers, so I just wanted to reset them all. The docs describe the command like this: Remove all stopped containers

> docker container prune 
WARNING! This will remove all stopped containers.
Are you sure you want to continue? [y/N] y
Total reclaimed space: 0B

docker container diff <container-name>

Sounds like I can see what changes had been made, which is quite useful, especially when you want to figure out what might better be a volume. The docs say: Inspect changes to files or directories on a container’s filesystem

> docker container diff site-stitcher
C /root
A /root/.config
A /root/.config/configstore
A /root/.config/configstore/update-notifier-npm.json