CODEWITHSUNDEEP
linuxdockerlinux-namespaces
Max Koretskyi
Max Koretskyi

Reputation: 105547

Why I don't see the namespace related to running docker container

I know I can use nsenter to execute host machine program, e.g. netstat, inside the running docker container like this:

sudo nsenter -t namespace_id -n netstat -putan

but for that I first need to figure out that namespace id.

I'm supposed to be able to do it like this:

# get container top level process id
$ docker inspect -f '{{.State.Pid}}' container_id

# use it to find the namespace id
$ lsns -t container_top_level_process_id

but when I do that lsns -t ... gives me empty output. What could be the reason for that? Is it possible that running the container through docker copmose somehow affects this?

Upvotes: -2

Views: 759

Answers (1)

larsks
larsks

Reputation: 312390

but for that I first need to figure out that namespace id.

No you don't; using the -t argument to nsenter you only need the PID of a process in the namespace. From the nsenter` man page:

`-t`, `--target` *PID*
     Specify a target process to get contexts from. The paths to the contexts specified by pid are:

So once you have the main process pid:

pid=$(docker inspect -f '{{.State.Pid}}' container_id)

You can use that directly with nsenter:

nsenter -t $pid -n netstat -tln

Upvotes: 3

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