Comment 26 for bug 1460177

Reviewed: https://review.opendev.org/715482
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=a0b18d553d75977fa48c6a64904b19c8fcd1b6de
Submitter: Zuul
Branch: master

commit a0b18d553d75977fa48c6a64904b19c8fcd1b6de
Author: Bence Romsics <email address hidden>
Date: Fri Mar 27 16:37:34 2020 +0100

    metadata-ipv6: DHCP namespace

    Send IPv6 metadata traffic (dst=fe80::a9fe:a9fe) to the metadata-agent.

    When running on IPv6 enabled system bind haproxy (i.e. the
    metadata-proxy) to 169.254.169.254 and to fe80::a9fe:a9fe also.

    We do not introduce new config options. The usual config options
    (enable_isolated_metadata, force_metadata, enable_metadata_proxy)
    now control the metadata service over both IPv4 and IPv6.

    This change series only affects the guests' access to the metadata
    service (over tenant networks). They change nothing about how the
    metadata-agent talks to Nova's metadata service.

    Metadata access over IPv6 is supposed to work both on dual-stack and
    v6-only networks.

    In order to enable the metadata service on pre-existing isolated
    networks during an upgrade, this change makes each dhcp-agent restart
    trigger a quick restart of dhcp-agent-controlled metadata-proxies,
    so they can pick up their new config making them also bind to
    fe80::a9fe:a9fe.

    Change-Id: If35f00d1fc9e4ab7e232660362410ce7320c45ba
    Partial-Bug: #1460177