Comment 4 for bug 1973051

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