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Python module to operate Linux namespaces
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README.md

About

Join the chat at https://gitter.im/procszoo/Lobby

Procszoo is a small Python module that gives you full power to manage your processes by Linux namespaces.

Contents

Goals


Procszoo aims to provide you a simple but complete tool and you can use it as a DSL or an embedded programming language which let you operate Linux namespaces by Python.

Procszoo gives a smart init program. I get it from baseimage-docker. Thanks a lot, you guys.

Procszoo does not require new version Python (but we support python3, too) and Linux kernel.

Resources

  • IRC channel: #procszoo on freenode.net

Requirements


Procszoo only requires Python standard libraries and the following packages

# if you want python3, please install following package's python3 version
# on RHEL/CentOS >= 6
sudo yum -y install autoconf gcc make glibc-headers
sudo yum -y install python-devel python-setuptools
# Debain/Ubuntu
sudo apt-get -y install autoconf gcc make libc6-dev
sudo apt-get -y install python-dev python-setuptools

Install

  1. You can install the procszoo by setuptools

     git clone https://github.com/xning/procszoo.git
     cd procszoo && sudo ./setup.py install
    
  2. You can install the procszoo by pip

     sudo pip install procszoo
    

Building

If you don't want to install it, then you can just clone it and do as the following commands,

git clone https://github.com/xning/procszoo.git
cd procszoo && make

By default, the above commands will build the program for your default Python version. If you want to build it for other Python version, just specify your desired Python interpretor through the PYTHON variable of the make command. Eg. To build for Python 3:

make PYTHON=/usr/bin/python3

If you will clone the procszoo in your home directory, On the RHEL/CentOS/Scientific Linux/Fedora, the default mode of your home directory is 0400, this will cause trouble, hence change it

chmod go+rx ${HOME}

Try It

Now you can try it in an interactive shell as follows (we suppose you have installed the procszoo)

richard_parker -l                       # what namsepaces are available?
richard_parker --available-c-functions  # what C functions are available?
richard_parker                          # get an interactive shell

If your Linux kernel doesn't support "user" namespaces, e.g., RHEL6/CentOS6, RHEL7/CentOS7, you need super user privileges

sudo richard_parker

And now, you can check things that we have in namespaces

  • programs get small pid number, e.g., 1, 2, etc., and there is only lo device and it is down

      ps -ef 
      ifconfig -a
    
  • open another terminal, we can see that the namespaces entries are different from last namespaces

      ls -l /proc/self/ns
    
  • if the kernel support and enable "user" namespaces, we are superuser at the same time

      id
    
  • if you have trouble to try the above steps, please refer to Known Issues.

Getting Your Feet Wet with the procszoo module


If you want to enable each namespace that your kernel supports

from procszoo.c_functions import *

if __name__ == "__main__":
    spawn_namespaces()

If you need to run your own program instead of an interactive shell,

from procszoo.c_functionss import *

if __name__ == "__main__":
    spawn_namespaces(nscmd=path_to_your_program)

Networks


Let's add network function to the new namespaces.

Because we will mount namespaces entries by the bind flag, we have to run richard_parker as the super user.

Except the shell that richard_parker will open, we need another interactive shell to make veth devices and add them to the new "net" namespace.

  • create a mount point

      mkdir /tmp/ns
    
  • create namespaces

      sudo richard_parker --ns-bind-dir=/tmp/ns
    
  • in richard_parker, configure the lo device

      ip link set lo up
    
  • in a new terminal, remount the /tmp/ns/net to /var/run/netns/net so ip command could operate it

      [ -d /var/run/netns ] | sudo mkdir -p  /var/run/netns
      sudo touch /var/run/netns/ns
      sudo mount --bind /tmp/ns/net /var/run/netns/ns
    
  • in the new terminal, create two devices and set one of them to the new namespace in this new terminal

      sudo ip link add veth0 type veth peer name veth1
      sudo ip link set dev veth1 netns ns
    
  • in this new terminal, configure veth0 device

      sudo ip link set veth0 up
      sudo ip addr add 192.168.0.10/24 broadcast 192.168.0.255 dev veth0
    
  • in richard_parker, configure veth1

      ip link set veth1 up
      ip addr add 192.168.0.11/24 broadcast 192.168.0.255 dev veth1
    
  • let's say "hello" from the new terminal

      ping -c 3 192.168.0.11
    
  • let's say "hello" from richard_parker

      ping -c 3 192.168.0.10
    

Docs


Known Issues


  • os.execv complains "permission deny"

    If running richard_parker unsuccessfully on RHEL/CentOS/Fedora, and get the following error messages like those

        os.execv(...)
    OSError: [Errno 13] Permission denied
    

    That's not a bug, please see the comment.

  • "ip netns" failed on RHRL6/CentOS6 and gave error messages as follows

    Object "nets" is unknown, try "ip help".
    

    We need a more latest iproute package, to do that please refer to here

Exported Functions, Objects, and Helpful CLI


The procszoo.utils exported following functions and objects, and I don't think that you need learn them all

  • objects

    • workbench
    • SpawnNamespacesConfig
  • key functions

  • helpful functions

    • atfork
    • sched_getcpu
    • mount
    • umount
    • umount2
    • unshare
    • setns
    • gethostname
    • sethostname
    • getdomainname
    • setdomainname
    • pivot_root
    • to_unicode
    • to_bytes
    • adjust_namespaces
    • get_namespace
    • get_available_propagations
    • get_current_users_and_groups
    • getresuid
    • getresgid
    • setresuid
    • setresgid
    • show_namespaces_status
    • show_available_c_functions
    • cgroup_namespace_available
    • ipc_namespace_available
    • net_namespace_available
    • mount_namespace_available
    • pid_namespace_available
    • user_namespace_available
    • uts_namespace_available
    • unregister_fork_handlers
  • Exceptions

    • CFunctionBaseException
    • CFunctionNotFound
    • NamespaceGenericException
    • UnknownNamespaceFound
    • UnavailableNamespaceFound
    • NamespaceSettingError
  • Helpful CLI

Test Platforms


I test the richard_parker and these scripts in tests/ on following archs

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