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[Lars Kellogg-Stedman <lars@xxxxxxxxxx>]

Public bug reported:

Nova currently provides nameserver information in network_data.json as a
globally-scoped "services" key.  E.g., from
https://specs.openstack.org/openstack/nova-
specs/specs/liberty/implemented/metadata-service-network-info.html#rest-
api-impact:

  {
  "links": [...],
  "networks": [...],
  "services": [
      {
          "type": "dns",
          "address": "8.8.8.8"
      },
      {
          "type": "dns",
          "address": "8.8.4.4"
      }
    ]
  }

This is problematic because nameserver information is actually provided
to OpenStack *per-subnet*, and nameservers that are reachable via one
subnet may not be reachable from others.  This is true outside of
OpenStack as well, and is generally handled by providing nameserver
information in interface configuration files (such as /etc/sysconfig
/network-scripts/ifcfg-eth0 on RHEL and derivatives).

Unfortunately, because Nova does not provide interface-scoped nameserver
information, it is not possible to correctly configure a server from
this information.  Depending on how /etc/resolv.conf is populated, this
can result in name resolution delays or failures if some system
interfaces are brought down.

While it may be too late to remove the global nameserver information, we
should *also* provide interface-scoped nameserver information in the
"networks" dictionary, something like:

  "networks": [
    {
      "network_id": "100dc63c-e8f8-46d1-a99f-6da4aca171b1",
      "type": "ipv4",
      "netmask": "255.255.255.0",
      "link": "tap14c7fd7d-81",
      "routes": [
        {
          "netmask": "0.0.0.0",
          "network": "0.0.0.0",
          "gateway": "10.9.8.1"
        }
      ],
      "ip_address": "10.9.8.2",
      "id": "network1",
      "services": [
        {
          "type": "dns",
          "address": "10.9.8.1"
        }
      ]
    }
  ]

This would allow system configuration tools to correctly configure
interface-scoped nameserver information.

** Affects: nova
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1693265

Title:
  network_data.json should provide interface-scoped nameserver
  information

Status in OpenStack Compute (nova):
  New

Bug description:
  Nova currently provides nameserver information in network_data.json as
  a globally-scoped "services" key.  E.g., from
  https://specs.openstack.org/openstack/nova-
  specs/specs/liberty/implemented/metadata-service-network-info.html
  #rest-api-impact:

    {
    "links": [...],
    "networks": [...],
    "services": [
        {
            "type": "dns",
            "address": "8.8.8.8"
        },
        {
            "type": "dns",
            "address": "8.8.4.4"
        }
      ]
    }

  This is problematic because nameserver information is actually
  provided to OpenStack *per-subnet*, and nameservers that are reachable
  via one subnet may not be reachable from others.  This is true outside
  of OpenStack as well, and is generally handled by providing nameserver
  information in interface configuration files (such as /etc/sysconfig
  /network-scripts/ifcfg-eth0 on RHEL and derivatives).

  Unfortunately, because Nova does not provide interface-scoped
  nameserver information, it is not possible to correctly configure a
  server from this information.  Depending on how /etc/resolv.conf is
  populated, this can result in name resolution delays or failures if
  some system interfaces are brought down.

  While it may be too late to remove the global nameserver information,
  we should *also* provide interface-scoped nameserver information in
  the "networks" dictionary, something like:

    "networks": [
      {
        "network_id": "100dc63c-e8f8-46d1-a99f-6da4aca171b1",
        "type": "ipv4",
        "netmask": "255.255.255.0",
        "link": "tap14c7fd7d-81",
        "routes": [
          {
            "netmask": "0.0.0.0",
            "network": "0.0.0.0",
            "gateway": "10.9.8.1"
          }
        ],
        "ip_address": "10.9.8.2",
        "id": "network1",
        "services": [
          {
            "type": "dns",
            "address": "10.9.8.1"
          }
        ]
      }
    ]

  This would allow system configuration tools to correctly configure
  interface-scoped nameserver information.

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