cloud-init should parse initramfs rendered netplan if present

[Ryan Harper]

initramfs-tools used to only execute klibc based networking with some
resolvconf hooks.

In recent releases, it has been greatly improved to use
isc-dhcp-client instead of klibc, support vlan= key (like in
dracut-network), bring up Z devices using chzdev, and generate netplan
yaml from all of the above.

Above improvements were driven in part by Oracle Cloud and in part by
Subiquity netbooting on Z.

Thus these days, instead of trying to reparse klibc files in
/run/net-*, cloud-init should simply import /run/netplan/$device.yaml
files as the ip=* provided networking information on the command line.
I do not currently see cloud-init doing that in e.g.
/cloudinit/net/cmdline.py

[Ryan Harper (raharper)]

On Wed, Jan 29, 2020 at 9:32 AM Dimitri John Ledkov <email address hidden> wrote:
>On Wed, Jan 29, 2020 at 3:17 PM Andreas Hasenack <email address hidden> wrote:
>
> cloud-init gets SRUed regularly as a new upstream version, i.e.:
>  cloud-init | 19.4-33-gbb4131a2-0ubuntu1~16.04.1 | xenial-proposed | source, all
>  cloud-init | 19.4-33-gbb4131a2-0ubuntu1~16.04.1 | xenial-updates  | source, all
>  cloud-init | 19.4-33-gbb4131a2-0ubuntu1~18.04.1 | bionic-proposed | source, all
>  cloud-init | 19.4-33-gbb4131a2-0ubuntu1~18.04.1 | bionic-updates  | source, all
>  cloud-init | 19.4-33-gbb4131a2-0ubuntu1~19.10.1 | eoan-proposed   | source, all
>  cloud-init | 19.4-33-gbb4131a2-0ubuntu1~19.10.1 | eoan-updates    | source, all
>  cloud-init | 19.4-33-gbb4131a2-0ubuntu1         | focal           | source, all
>
>
> Do these initramfs-tools improvements you speak of exist since xenial?
>
>
> Netplan rendering is available from xenial and up:
>
> ./initramfs-tools-0.122ubuntu8.16/scripts/functions:_render_netplan() {
> ./initramfs-tools-0.130ubuntu3.9/scripts/functions:_render_netplan() {
> ./initramfs-tools-0.131ubuntu19.2/scripts/functions:_render_netplan() {
> ./initramfs-tools-0.133ubuntu10/scripts/functions:_render_netplan() {
> ./initramfs-tools-0.133ubuntu12/scripts/functions:_render_netplan() {

Xenial images do not use netplan by default; however, cloud-init in Xenial
can read/parse it and render ifupdown as needed.

> Vlan support is available from eoan and up:
>
> ./initramfs-tools-0.133ubuntu10/init: vlan=*)
> ./initramfs-tools-0.133ubuntu12/init: vlan=*)
>
> If desired Vlan support can be backported.

Are the vlan values exported into rendered netplan?

> Note neither of above is available on Debian.

Generally, we can have cloud-init look for rendered netplan files, and prefer them over
the klibc files when present.

[Dimitri John Ledkov (xnox)]

Yes Vlan is defined in the runtime yaml, as native vlan.... With many keys set that cloud-init doesn't generate, for example the fact that that connection is a critical one and should not be torn down.

[Dimitri John Ledkov (xnox)]

$ cat /run/netplan/encc000.2653.yaml
network:
  version: 2
  renderer: networkd
  ethernets:
    encc000:
      match:
        macaddress: "96:89:5a:96:15:30"
      set-name: encc000
  vlans:
    encc000.2653:
      id: 2653
      link: encc000
      addresses:
        - "10.245.236.14/24"
      gateway4: "10.245.236.1"
      nameservers:
        addresses: ["10.245.236.1"]

$ sudo cat /proc/cmdline
ip=10.245.236.14::10.245.236.1:255.255.255.0:s1lp14:encc000.2653:none:10.245.236.1 vlan=encc000.2653:encc000 url=ftp://10.13.0.2:21/ubuntu-live-server-20.04/focal-live-server-s390x.iso --- quiet

[Ryan Harper (raharper)]

https://github.com/canonical/cloud-init/pull/238

[Ryan Harper (raharper)]

@Dimitri

Interested in your thoughts here:

https://github.com/canonical/cloud-init/pull/238#issuecomment-598408582

[Dimitri John Ledkov (xnox)]

maybe casper can hack this....

[Joshua Powers (powersj)]

Plan is to look at fixing this in Casper for Focal release. For post-focal release, we will work on a fix in cloud-init.

[Dimitri John Ledkov (xnox)]

This is awaiting cloud-init casper initramfs-tools livecd-rootfs pending changes all getting accepted and migrated to release pocket, and new image built using all of the above, before further tests/development can happen.

[Dimitri John Ledkov (xnox)]

casper has been changed to generate cloud.cfg instead of netplan, thus no further work in cloud-init is required for focal.

Closing this issue as fix released in casper & z project.

It would be nice for cloud-init to do what was originally asked, but that is a feature request of a lower priority now, that needs further spec / implementation as discussed on github PR.

[Dan Watkins (oddbloke)]

Ryan has started work on this, moving to In Progress.

[Joshua Powers (powersj)]

The portions required for focal are in and the remaining items are additional for cloud-init. Dropping req4focal tag.

[James Falcon (falcojr)]

Tracked in Github Issues as https://github.com/canonical/cloud-init/issues/3602