lxc / cloud-init network config: insert network config into a container

README.md

lxc-netcfg

script to insert some network configs into an lxc container and then start it. supports replacing @<nicname>_addr with the address of nicname inside the container.

has builtin configs for bond and dhcp4and6.

Notes:

• bond is known not working (bonds do not work with ifupdown in a container).
• if 'mode' starts with 'cc', it will write /etc/cloud/cloud.cfg.d/99-network-config.cfg otherwise it will write /var/lib/cloud/seed/nocloud-net/network-config

Example config

providing dhcp4and6 will write a network config like the following to the /etc/cloud/cloud.cfg.d path.

network: 
  version: 1
  config:
    - type: physical
      name: eth0
      mac_address: 00:16:3e:9c:58:7a
      subnets:
        - type: dhcp
          control: auto
        - type: dhcp6
          control: auto

lxc-netcfg

#!/bin/bash
set -f
set -e
name=$1
mode="${2:-bond}"
fpath=${3}

[ -n "$name" ] || { echo "must give name"; exit 1; }
# pastebinit `which lxc-chroot`
# http://paste.ubuntu.com/24198752/

bond() {
cat <<"EOF"
version: 1
config:
  - type: physical
    name: iface0
    mac_address: @eth0_addr
  - type: physical
    name: iface1
    mac_address: @eth1_addr
  - type: bond
    name: bond0
    bond_interfaces: [iface0, iface1]
    params:
      bond-mode: active-backup
    subnets:
      - type: dhcp
        control: auto
EOF
}
dhcp4and6() {
   cat <<"EOF"
version: 1
config:
  - type: physical
    name: eth0
    mac_address: @eth0_addr
    subnets:
      - type: dhcp
        control: auto
      - type: dhcp6
        control: auto
EOF
}

ccify() {
   local out=""
   out=$("$@") || return
   echo "network:"
   printf "%s" "$out" | sed 's,^,  ,'
}

lxc init ubuntu-daily:zesty $name
lxc network attach lxdbr0 $name eth1
# lxc-chroot has access to /var/lib/cloud/seed/nocloud-net/
# despite https://github.com/lxc/lxd/issues/3088 because it does
# a 'start', which will get those things rendered.
# the start just doesn't actually run an init.
out=$(lxc-chroot "$name" sh -ec '
   for i in /sys/class/net/*; do
      [ -e "$i/address" ] || continue
      n=${i##*/}
      read addr < "$i/address"
      echo $n,$addr
   done
')

seds=( )
for pair in $out; do
   addr=${pair#*,}
   nicname=${pair%,*}
   echo "@${nicname}_addr -> $addr" 1>&2
   seds=( "${seds[@]}" -e "s/@${nicname}_addr/${addr}/" )
done

cmd=( )
case "$mode" in
   bond|dhcp4and6)  cmd=( $mode );;
   cc-bond|cc-dhcp4and6)  cmd=( ccify "${mode#cc-}" );;
   *)
      [ -f "$mode" ] ||
         { echo "$mode: not a file or known mode"; exit 1; }
      cmd=( cat "$mode" )
      if [ "${CCIFY:-0}" != "0" ]; then
         cmd=$(ccify cat "$mode")
      fi
esac

out=$("${cmd[@]}")
cfg=$(printf "%s" "$out" | sed "${seds[@]}")

if [ -z "$fpath" ]; then
   case "$mode" in
      cc-*) fpath="/etc/cloud/cloud.cfg.d/99-network-config.cfg";;
      *) fpath="/var/lib/cloud/seed/nocloud-net/network-config";;
   esac
fi

printf "%s\n" "$cfg" | lxc file push - "$name/$fpath"
printf "== %s ==\n%s\n" "$fpath" "$cfg"
lxc start "$name"