MR up for review: https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/546.

Tested on Google Cloud Platform VMs with a configured load balancer.

Patch merged upstream https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/commit/ccbae2422e0e415af1cc742fd3e35307415dda87.

As Wei Shi <wshi> wrote:

forwarded_ip (in metadata) will be set to the Frontend IP (LB) after the load balancer is created,

# curl --silent -L -H "Metadata-Flavor: Google" "http://metadata.google.internal/computeMetadata/v1/instance/network-interfaces/0/forwarded-ips/0"
10.1.2.99

---

The configure steps I used to mimic the LB setup:
https://cloud.google.com/load-balancing/docs/internal/setting-up-internal#configure-test-environment

Image: RHEL-8.3.0-Snapshot-2.0 (NetworkManager-cloud-setup-1.26.0-6.el8.x86_64)

After LB is created, forwarded_ip in metadata will be set.
# curl --silent -L -H "Metadata-Flavor: Google" "http://metadata.google.internal/computeMetadata/v1/instance/network-interfaces/0/forwarded-ips/0"
10.1.2.99

stop nginx on all machines except vm-a1

Connect to the iLB addr will get error:
vm-client:~# curl http://10.1.2.99
curl: (7) Failed to connect to 10.1.2.99 port 80: Connection refused

Uncomment "Environment=NM_CLOUD_SETUP_GCP=yes" in /lib/systemd/system/nm-cloud-setup.service

vm-a1# systemctl restart nm-cloud-setup

vm-a1# ip route show table local
...
local 10.1.2.99 dev eth0 proto static scope host metric 100
...

Connect to the iLB addr will get the nginx sample page on vm-a1:
vm-client:~# curl http://10.1.2.99
HTTP/1.1 200 OK
...
...

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (NetworkManager bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2020:4499