Comment 19 for bug 1636912

On Thu, Oct 27, 2016 at 3:57 PM, Martin Pitt <email address hidden> wrote:

> > cloud-init expects networking to be up, like 'networking.service'
> before it runs..
>
>
> It seems to me that this might have to be split into two parts then -- one
> that can provide network config which runs early and does not require
> networking, and one that can use the network to configure other bits?
>

We already do this. cloud-init-local.service runs before networking; it
examines for *local* non-network seeds (like nocloud-net, or a config-drive
)
If that's present, it's sourced and used.

However, if there isn't a local seed, then we must search again *once*
networking is up.

This works just fine with 'networking.service' due to the "atomic" nature
of ifup where once
the oneshot service runs, we can assume that networking is up.

However, networkd runs and asynchronously brings up networking; which is
fine but we now
no longer have a clear checkpoint at which cloud-init can run with
networking up but before
we're at the full 'network-online.target'

I'm not sure how to close the subtle distinction between 'networking' and
'systemd-networkd'
but it's clearly different with no obvious way to make them equivalent.

>
> > So why shouldn't we use networkd-wait-online ?
>
> You can use the program. I said that it might not be the best idea to
> use After=s-n-wait-online.service, as that would block the entire cloud-
> init.service and with it the entire boot (as cloud-init.service has very
> strong dependencies) if there is no network available.
>

It actually works quite well, except the netplan generator only creates a
wants for systemd-networkd, so nothing *wants* the netword-wait-online
unless we add it; this is problematic for cloud-init on a system which
doesn't
have a netplan config (where networkd isn't going to run).

>
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> https://bugs.launchpad.net/bugs/1636912
>
> Title:
> systemd-networkd runs too late for cloud-init.service (net)
>
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