Comment 10 for bug 1848738

Reviewed: https://review.opendev.org/690731
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=1f7cd398d675400494b77371f107a0bd2c3b2e20
Submitter: Zuul
Branch: stable/queens

commit 1f7cd398d675400494b77371f107a0bd2c3b2e20
Author: Slawek Kaplonski <email address hidden>
Date: Fri Oct 18 07:04:43 2019 +0200

    Fix mismatch of tags in dnsmasq options

    In some cases (I don't know exactly how) it may happend that
    when new subnet, e.g. IPv6 is added to the network, subnets
    can change their order based on uuid.
    As before this patch we were using in dnsmasq options tags like
    "tagN" for subnets (where N was just number based on position of
    the subnet in the sorted list) it could happend sometimes that
    dnsmasq ended up with mismatch of tags configured in "dhcp-range"
    cmd option and set in "opts" file. That caused problem with serving
    proper DHCP options to the vms.

    This patch fixes this issue by using tags with format:
    "subnet-<uuid>" where uuid is id of the subnet. That was it's not
    based on order of subnets in the list and will always match with tag
    configured in opts file for specific subnet.

    As we was currently using port id as tag for "per port" DHCP options,
    this patch changes that to use tags like "port-<uuid>" to make it
    consistent with options configured "per subnet" and to make it easier
    to debug from where each option comes.

    Conflicts:
        neutron/agent/linux/dhcp.py
        neutron/tests/unit/agent/linux/test_dhcp.py

    Change-Id: Idaea33d62fa31edd7149ec916ec314438375724a
    Partial-Bug: #1848738
    (cherry picked from commit 88f2073526c2add7e8aa07656caec4c35c8b8459)
    (cherry picked from commit a0730e684d54796fce0574bb314b679bcdd58c76)
    (cherry picked from commit ba12b9e36916de4f4635de530defcbffc6dc1a53)