Add veth pair to Docker container

add_veth_pair.sh

# Fortemente baseado em https://github.com/jpetazzo/pipework
function add_veth_pair {
  pid=$1 ; ipaddr=$2 ; container_ifname=$3
  echo "Add interface $container_ifname with ip $ipaddr to container pid $pid"
  local_ifname="v${container_ifname}l${pid}"
  guest_ifname="v${container_ifname}g${pid}"
  bridge='docker0'
  mtu=$(ip link show $bridge | awk '{print $5}')
  if ip link show "$local_ifname" >/dev/null 2>&1 ; then 
    ip link del "$local_ifname"
  fi
  ip link add name "$local_ifname" mtu "$mtu" type veth peer name "$guest_ifname" mtu "$mtu"
  ip link set "$local_ifname" master "$bridge"
  ip link set "$local_ifname" up
  ip link set "$guest_ifname" netns "$pid"
  ip netns exec "$pid" ip link set "$guest_ifname" name "$container_ifname"
  ip netns exec "$pid" ip addr add "$ipaddr" dev "$container_ifname"
  ip netns exec "$pid" ip link set "$container_ifname" up
  ipaddr=$(echo "$ipaddr" | cut -d/ -f1)
  ip netns exec "$pid" arping -c 1 -A -I "$container_ifname" "$ipaddr" >/dev/null 2>&1 | :
}