I am not able to exec into container which uses containerd as runtime.
I need to check some processes running inside the container. Is there any way to exec into container?
I am able to list containers using ctr cli.
Any help would be appreciated.
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I don't have much experience but containerd as runtime but with docker, the exited process don't show up in the `docker ps` command and need to explicit add `-a` flag as `docker ps -a`. Could you verify that the container process is still running? if you are just asking about the docker command (I assume not), `docker exec` is what is used for `exec`ing into the containers. – Krishna Chaurasia Jun 03 '21 at 11:35
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I don't know anything about docker, but searching for `docker how to exec into a container` gives a lot of results. – marsh-wiggle Jun 03 '21 at 11:36
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Containers are up and running . As they use containerd as runtime I didn't find any way to exec into container. – Snehal Hodage Jun 03 '21 at 11:38
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There is typically a higher level tool (like Docker) in front of containerd. Are you running Docker in this environment? Or something else? Absent any other solution, you can use `nsenter` to run commands inside a container namespace. – larsks Jun 03 '21 at 11:41
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1Is this a question about docker? You've indicated you are trying to use ctr, but tagged the question with docker. – BMitch Jun 03 '21 at 11:42
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A container normally runs only one process; if the container is running, its process is too. – David Maze Jun 03 '21 at 11:45
5 Answers
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exec is a sub-command of command task,try
ctr -a $CONTAINERD_HOST -n $NAMESPACE t exec -t --exec-id $exec_id --fifo-dir /tmp $executor_id bash
sp x
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I believe `$exec_id` can be set to any value you please; the help for `task exec` describes it as `exec specific id for the process`. In my testing, the value was not important. Presumably it is used for logging somewhere in the cgroup infrastructure. – Resigned June 2023 Dec 21 '22 at 06:02
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An alternative to the ctr command that K D Singh wrote about is crictl, so you can use it like so
crictl exec -it 9b47589560c6d /bin/sh
where 9b47589560c6d would be replaced by your container id (doesn't work with names as far as I know).
lejlun
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Russell Waite
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Firstly run to learn container id:
sudo crictl ps -a
Be careful to use container id (first three letters enough):
sudo crictl exec -it 27e /bin/sh
With ctrctl, we can give seperate commands for images, container and pod (like rmi: remove image, rmp: remove pod, rm: remove container)
Commands: https://github.com/kubernetes-sigs/cri-tools/blob/master/docs/crictl.md
Ömer Sezer
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You can use exec command
docker exec -it <container name> /bin/sh
The -i option keeps the STDIN open and -t allocates a pseudo-tty
This will open the shell and you can execute any command inside the running container.
