19.04 minimal images on GCE intermittently fail to set up networking

This bug was originally filed in Launchpad as [LP: #1822353](https://bugs.launchpad.net/cloud-init/+bug/1822353)

Launchpad details

affected_projects = []

assignee = None

assignee_name = None

date_closed = 2020-11-07T04:17:19.483991+00:00

date_created = 2019-03-29T17:26:50.547993+00:00

date_fix_committed = None

date_fix_released = None

id = 1822353

importance = high

is_complete = True

lp_url = https://bugs.launchpad.net/cloud-init/+bug/1822353

milestone = None

owner = philroche

owner_name = Philip Roche

private = False

status = expired

submitter = philroche

submitter_name = Philip Roche

tags = ['id-5c7fbddcf1364b63892a22c9', 'id-5c9d168ed6c5704cac05e595', 'id-5d0a33dc7c02f24574ae04aa']

duplicates = []

_Launchpad user **Philip Roche(philroche)** wrote on 2019-03-29T17:26:50.547993+00:00_

Related to https://bugs.launchpad.net/cloud-init/+bug/1766287 I'd like to open a new bug following Disco minimal images failing to set up networking due to similar reasons as lp:1766287 with the only difference being that no nic was found.

A workaround was found to set up cloud-init service config:

/etc/systemd/system/cloud-init-local.service.d/gcp.conf
```
[Unit]
After=systemd-udev-trigger.service

[Service]
ExecStartPre=/bin/udevadm settle
```

The goal of this workaround is to:

1) ensure that cloud-init-local.service runs after
systemd-udev-trigger.service starts (this is what triggers
udev coldplug events, like plugging in the nic)
2) Run udevadm settle before we start cloud-init local so that any
nic processing is completed before cloud-init starts looking for
a nic.

Currently this is only required on minimal images but there is a
chance it could occur in base images too should they boot quick
enough. Minimal disco does not have snap preseeding as base images do and
due to snap preseeding running before cloud-init it makes it extremely unlikely to
happen in base images.

I understand that cloud-init might not be the place to fix the issue for all images but I'd like to re-open this bug to start that discussion.

I have attached cloud-init logs, netplan yaml, image manifest and sosreports from an instance that failed to set up networking.