[Bug 1621507] Re: initramfs-tools configure_networking() fails to dhcp ipv6 addresses

[Scott Moser]

As I suggested in bug 1634176, I think that we can extend the 'ip='
parameter to work as it has a 'autoconf' parameter in it, which
indicates the type of "auto" configuration to do:

klibc documents the previous ip= syntax at README.ipconfig [1].
  <client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf>

My suggestion is to extend the 'autoconf' parameter. Previously the
supported documented values were 'rarp', 'bootp', 'both', 'dhcp', 'all',
'off', 'static', 'none'. I suggest we add 'dhcp6' to the the list.

We could also support 'dhcp4,dhcp6' or 'dhcp+dhcp6' indicating both
should be tried or possibly dhcp6 if and only if dhcp4 failed.  I think
though, for the immediate use case that just adding 'dhcp6' to the
autoconf types would suffice.

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https://bugs.launchpad.net/bugs/1621507

Title:
  initramfs-tools configure_networking() fails to dhcp ipv6 addresses

Status in MAAS:
  Fix Released
Status in initramfs-tools package in Ubuntu:
  In Progress
Status in isc-dhcp package in Ubuntu:
  Fix Released
Status in klibc package in Ubuntu:
  Won't Fix
Status in open-iscsi package in Ubuntu:
  Fix Released
Status in initramfs-tools source package in Xenial:
  Triaged
Status in isc-dhcp source package in Xenial:
  Fix Released
Status in klibc source package in Xenial:
  Won't Fix
Status in open-iscsi source package in Xenial:
  Fix Released
Status in initramfs-tools source package in Yakkety:
  In Progress
Status in isc-dhcp source package in Yakkety:
  Fix Released
Status in klibc source package in Yakkety:
  Won't Fix
Status in open-iscsi source package in Yakkety:
  Fix Released
Status in klibc package in Debian:
  New

Bug description:
  initramfs' configure_networking function uses ipconfig to configure the network.
  ipconfig does not support dhcpv6.  See: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=627164

  Related bugs:
    * bug 1229458: grub2 needed changes
    * bug 1621615: network not configured when ipv6 netbooted into cloud-init

  [Impact]

  It is not possible to netboot Ubuntu with a network-based root
  filesystem in an ipv6-only environment.  Anyone wanting to netboot in
  an ipv6-only environment is affected.

  These uploads address this by replacing the one-off klibc dhcp client
  (IPv4-only) with the defacto standard isc-dhcp-client, and thereby
  provide both ipv6 and ipv4 DHCP configuration.

  [Test Case]

  See Bug 1229458.  Configure radvd, dhcpd, and tftpd for your ipv6-only
  netbooting world.  Pass the boot process an ipv6 address to talk to,
  and see it fail to configure the network.

  [Regression Potential]

  1) This increases the uncompressed initramfs size by approximately 500KB, since isc-dhcp-client is added, but klibc is still needed for some other things, and is therefore present.  On systems with a very small /boot partition, this could result in failure to upgrade the initramfs.
  2) In at least some cases, DHCP network configuration shifts from klibc's ipconfig to isc-dhcp-client's dhclient.  This should be of minimal risk, as isc-dhcp-client is in very very widespread use.  In the event of a regression, network boot would fail, but the prior kernel should still be bootable.

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