How to get container ID from within the container with cgroup v2

[rimelek (Ákos Takács)]

Can you share why you need to know the container id inside the container itself?

I remembered an issue wich was related to cgroup v2 and commands in the container, I am not sure that helps, but I leave it here anyway

/proc/1/cgroups does not tell if I am inside of contianer

In aim to check if we are inside of container we need to type (it is taken from the web): # docker container exec -it ub bash root@8d6a3b7407c5:/# cat /proc/1/cgroup 0: ‘ub’ is the name of Ubuntu Docker image. Before I created container like that: # docker container run -itd --name ub ubuntu:latest bash 8d6a3b7407c5cf0f7c38e1a64ebb9fe0ab61b336cc2e60cdff04c8821145e1c7 As you can see inside of my container there is no any ‘docker’ word after the /. Why?

And now that I shared this link I realized I already answered a question related to getting the container id which might help you as well

How can detect container ID immediately after container start?

I cans ee multiple potential problems: You should not use $(date +%Y-%m-%d-%H.%M.%S) multiple times, because the time between the two execution can change, so you will refer to a wrong container name.Save the result to a variable, and use the variable multiple times. I am not sure if yoiu really wanted to do this: pwd & sudo docker ... If you want to run your container in the background, you can just use the --detach or -d flag, but then you need to run a command in the container which keeps …

You could for example save the cid file in a folder that is mounted into the container so you just read a file in the container that you mounted.