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How to know the process id mapping for container instance on Windows host

Hello,
I'm having my development laptop running Windows 10.0.19044 Build 19044
I'm running docker desktop (Client and server versions are 20.10.14) using WSL 2 as recommended by Microsoft which delivers better performance than the Hyper-V backend.

My question:
I can see the instructor can relate the PID within a container (Usually, a small number 1, 8) to the process id in his mac laptop. I want to know to which Windows process the command relates?

To clarify more about my question:
In chapter 3: Run and Operate Containers
Video: Interacting with Containers
From minute: 3:40
To minute: 4:10

Thanks

Answers

  • gouravshah
    gouravshah Posts: 95

    @ashraf.fouad your questions is clear as the open blue sky :)

    What you should be looking at really is how to get console/ssh access to the WSL2 environment. Because once you do, thats the host running docker daemon. Thats what you would compare the pid output with within the container.

    I am trying to find this answer myself as I do not use a windows WSL2 environment. I am sharing a couple of resources here,

    https://www.google.com/search?q=connect+to+wsl2+via+&client=firefox-b-d&ei=_quoYqDVL6GSseMP98GOkAk&ved=0ahUKEwigzMHTo634AhUhSWwGHfegA5IQ4dUDCA0&uact=5&oq=connect+to+wsl2+via+&gs_lcp=Cgdnd3Mtd2l6EAMyBQgAEIAEMgkIABAeEMkDEBY6BwgAEEcQsANKBAhBGABKBAhGGABQogtYogtg7A1oA3ABeACAAVaIAVaSAQExmAEAoAEByAEIwAEB&sclient=gws-wiz

    https://www.hanselman.com/blog/how-to-ssh-into-wsl2-on-windows-10-from-an-external-machine

    Can you check these and also let us know if any of these solutions work for you ?

  • ashraf.fouad
    ashraf.fouad Posts: 26

    :smile: I try to be clear in my questions to get such clear answers ;)

    This seems quite interesting, as also I was trying to discover where docker logs are on windows and this stackoverflow link helped a lot.

    Referring to docker documentation Docker Desktop WSL 2 backend

    C:\Users\ashra>wsl -l -v
      NAME                   STATE           VERSION
    * docker-desktop-data    Running         2
      docker-desktop         Running         2
    

    It was mentioned in same page that the above two destros are special-purpose internal Linux distros, and not to be used for general development.

    Docker Desktop does not require any particular Linux distros to be installed. The docker CLI and UI all work fine from Windows without any additional Linux distros. However for the best developer experience, we recommend installing at least one additional distro and enabling Docker support

    I tried to connect to this special purpose distro without luck, needs more investigation, I will post again in this thread when reaching something useful.

    THanks for the direction.

  • gouravshah
    gouravshah Posts: 95

    @ashraf.fouad this is great digging around about how docker is been setup on windows with wsl2. While you are exploring further, here is one hack I would give you to get pid, network etc. from the host

    docker run -it --rm --pid=host --privileged --net host  ubuntu bash
    

    when you launch a container with above options,

    • It would launch a container with ubuntu, and give you bash to work with
    • It creates a temporary container, as in, when you exit, it will be deleted ( due to --rm options). Good for one time exploration
    • creates a container which connect to host's PID namespace . This would help you list the processes from the underlying host (assume wsl2 setup) when you run ps -ef --forest
    • It would further connect to host's network namespace, allowing you to compare host network vs container network.

    Give this a try to and do let me know if this helps you compare the namespaces between container and the host.

  • ashraf.fouad
    ashraf.fouad Posts: 26

    Thanks @gouravshah it is working, I'm sharing relevant section from outcome:

    root      1968   578  0 18:13 ?        00:00:00  \_ /usr/bin/containerd-shim-runc-v2 -namespace moby -id cc30f7208cf77e7ccae4739d39a6e74303b120a7a17ad71d61d
    root      1989  1968  0 18:13 pts/0    00:00:00  |   \_ bash
    root      2040  1968  0 18:17 ?        00:00:00  |   \_ bash
    

    Also, I found how to connect to a Linux distro from WSL using this video Docker Desktop & WSL 2 Integration Deep Dive

    C:\Users\ashra>wsl -l
    Windows Subsystem for Linux Distributions:
    docker-desktop-data (Default)
    docker-desktop
    Ubuntu
    
    C:\Users\ashra>wsl -d docker-desktop
    ASH-Lenovo340:/tmp/docker-desktop-root/mnt/host/c/Users/ashra#
    

    Now your are connected to docker, then I tried the command

    ps -ef --forest
    

    but I found -- forest not recognizable in this distro, but using the normal

    ps -ef
    

    The following was information running container and its related processes

     2077 root      0:00 /usr/bin/containerd-shim-runc-v2 -namespace moby -id cc30f7208cf77e7ccae4739d39a6e74303b120a7a17ad71d61dc4158353e381b -address /var/ru
     2098 root      0:00 bash
     2151 root      0:00 bash
    

    Many thanks for your support :smile:

  • gouravshah
    gouravshah Posts: 95

    Great ! Thanks @ashraf.fouad

    wsl -d docker-desktop
    wsl -d docker-desktop-data
    

    These commands would be useful for me to pass on to my students when they want to connect to the host.

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