Debian: install failing at ansible bootstap due to DNS misconfiguration

[Andre Kantek]

Brief Description
-----------------
It was detected that if DNS server is not set on localhost.yaml, but resolv.conf already possesses the correct nameservers (collected prior to the installation via DHCP) the installation is failing due to lack of address resolution during the docker image download phase.

Severity
--------
<Minor: System/Feature is usable with minor issue>

Steps to Reproduce
------------------
1) obtain the DNS servers addresses prior to the installation (by manually editing resolv.conf or using DHCP)
2) start ansible bootstrap

Expected Behavior
------------------
Bootstrap works properly

Actual Behavior
----------------
Bootstrap does not finish with success

Reproducibility
---------------
Reproducible

System Configuration
--------------------
AIO-SX

Workaround
----------
set the variable dns_servers in localhost.yaml

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/starlingx/ansible-playbooks/+/841461

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/starlingx/config/+/843012

[OpenStack Infra (hudson-openstack)]

Change abandoned by "Andre Kantek <email address hidden>" on branch: master
Review: https://review.opendev.org/c/starlingx/ansible-playbooks/+/841461
Reason: It was decided that the default files only handle IPv4 so the operator will have to provide publiuc IPv6 DNS explicitly

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/starlingx/config/+/843012
Committed: https://opendev.org/starlingx/config/commit/ba287f2aebb51357e5974dc6a57b199ead9a1a09
Submitter: "Zuul (22348)"
Branch: master

commit ba287f2aebb51357e5974dc6a57b199ead9a1a09
Author: Andre Fernando Zanella Kantek <email address hidden>
Date: Mon May 23 14:00:59 2022 -0400

    Do not add '::1' as a DNS nameserver

    During bootstrap on Debian it was noticed that the file resolv.conf
    is receiving 'nameserver ::1' along with the other DNS servers set
    in localhost.yaml. This happens because the initial configuration
    is being applied and the only address available for the host is
    '::1'. Since ::1 is not a useful DNS address it might lead wrong
    request execution during address resolution.

    This change evaluates the gethostbyname response and if only contains
    '::1' it will ignore it.

    Test Plan:
    PASS Install IPv4 on Debian (AIO-SX)
    PASS Install IPv6 on Debian (AIO-SX)
    PASS Install IPv4 on CentOS (AIO-SX)
    PASS Install IPv6 on CentOS (AIO-SX)

    Closes-Bug: 1973051

    Signed-off-by: Andre Fernando Zanella Kantek <email address hidden>
    Change-Id: Ifb6f711fa832d7320872617cb9b508c156f2ae79