Get the network interface names as seen outside the docker namespace

docker_iflinks.py

#!/usr/bin/env python2

# get the network interface names as seen outside the docker namespace
# TODO: add dumping stats 

import os.path
import pyroute2
import sys
import subprocess


def get_attr(link, name):
    attr_val = ""
    for attr in link['attrs']:
        if attr[0] == name:
           attr_val = attr[1]
    return attr_val

def is_loopback(link):
    return (link['flags'] & 0xffffffff & pyroute2.netlink.rtnl.ifinfmsg.IFF_LOOPBACK) == pyroute2.netlink.rtnl.ifinfmsg.IFF_LOOPBACK

def get_nons_links():
    links_no_ns = {}

    ip = pyroute2.IPRoute()
    for link in ip.get_links():
        if is_loopback(link):
            continue
        links_no_ns[link['index']] = get_attr(link, "IFLA_IFNAME")
    return links_no_ns

def get_docker_container_ns(container_id):
    namespace_id = subprocess.check_output(['docker', 'inspect', "--format={{.NetworkSettings.SandboxKey}}", container_id]).strip()
    namespace_id = os.path.basename(namespace_id)
    return namespace_id

def get_ns_links(ns_id):
    links_ns = {}
    pyroute2.netns.NETNS_RUN_DIR = '/var/run/docker/netns'
    ns = pyroute2.NetNS(ns_id)
    for link in ns.get_links():
        if is_loopback(link):
            continue
        links_ns[link['index']] = get_attr(link, "IFLA_IFNAME")
    return links_ns

def docker_container_ids():
    x = subprocess.check_output(['docker', 'ps', "--format={{.ID}}"]).split("\n")
    x = x[0:-2]
    return x


if __name__ == "__main__":
    cids = docker_container_ids()
    if len(sys.argv) > 1:
        cids = sys.argv[1:]

    all_non_ns_links = get_nons_links()

    for container_id in cids:
        links_ns = get_ns_links(get_docker_container_ns(container_id))
        print container_id
        for k,v in links_ns.iteritems():
            print "\t%d %s %s" % (k, v, all_non_ns_links[k+1])