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Chapter 4. Using an integrated DNS service

The Red Hat OpenStack Services on OpenShift (RHOSO) DNS service (designate) integrates with the Networking service (neutron) to provide automatic record set creation for ports and through the Compute service (nova), virtual machine instances.

Cloud administrators use the DNS service to create a zone which they associate to a network. Using this network provided by their cloud administrator, cloud users can create a virtual machine instance, port, or floating IP and the DNS service automatically creates the necessary DNS records.

During DNS service deployment, the Networking service (neutron) loads the extension, dns_domain_ports. This extension enables you to add the following DNS attributes to RHOSO ports, networks, and floating IPs.

Note

For more information, see the optional step in Deploying the DNS service.

Expand
Table 4.1. DNS settings supported by the RHOSO Networking and DNS services
ResourceDNS nameDNS domain (zone)

Ports

Yes

Yes

Networks

No

Yes

Floating IPs

Yes

Yes

Note

For DNS domains that are specified on both a network and a floating IP, the domain on the port of the floating IP takes precedence over the domain set on the network.

The topics included in this section are:

4.1. Setting up a project for DNS integration
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Red Hat OpenStack Services on OpenShift (RHOSO) cloud administrators create the required zones, networks, and subnets that cloud users must specify when they create virtual machine instances, ports, or floating IPs. Because the RHOSO Networking service (neutron) is integrated with the DNS service (designate), when cloud users create these objects, they are automatically added to the DNS service.

Prerequisites

  • You have the oc command line tool installed on your workstation.
  • You are logged on to a workstation that has access to the RHOSO control plane as a user with cluster-admin privileges.
  • The network used for ports and VMs cannot have the attribute router:external set to True. When creating the network, the --external option must not be specified.
  • The network must be one of the following types: FLAT, VLAN, GRE, VXLAN or GENEVE.

  • For VLAN, GRE, VXLAN, or GENEVE networks, the segmentation ID must be outside the ranges configured in the Networking service ml2_conf.ini file.

    The ml2_conf.ini file resides on the Controller node host in /etc/neutron/plugins/ml2/ml2_conf.ini. Use the following table for determining which section and option to consult for your network segmentation ID range:

    Expand
    Table 4.2. ml2_conf.ini options used to set network segmentation IDs
    Type of networkSectionOption

    GENEVE

    [ml2_type_geneve]

    vni_ranges

    GRE

    [ml2_type_gre]

    tunnel_id_ranges

    VLAN

    [ml2_type_vlan]

    network_vlan_ranges

    VXLAN

    [ml2_type_vxlan]

    vni_ranges

Note

If these prerequisites are not all met, the Networking service creates a DNS assignment in the internal resolvers using the default dns_domain value, openstacklocal..

Procedure

  1. Access the remote shell for the OpenStackClient pod from your workstation: 

    $ oc rsh -n openstack openstackclient

  2. Create the zone that you want users in a particular project to create DNS entries with.

    Example

    In this example, the cloud administrator creates a zone called example.com. and specifies that users in the project ID, f75ec24a-d361-ab86-54c0-dfe6093245a3, have permission to add record sets to the zone: 

    $ openstack zone create --email example@example.com example.com. --sudo-project-id f75ec24a-d361-ab86-54c0-dfe6093245a3
    Note

    The DNS domain must always be a fully qualified domain name (FQDN), meaning it will always end with a period.

  3. Create the network that you want users in a particular project to create DNS entries with.

    Example

    In this example, the cloud administrator creates a network, example-network, that uses the earlier created zone, example.com., and a segmentation ID, 2017, that is outside of the range defined in ml2_conf.ini: 

    $ openstack network create --dns-domain example.com. \
--provider-segment 2017 --provider-network-type geneve \
example-network

  4. On the network, create a subnet.

    Example

    In this example, the cloud administrator creates a subnet, example-subnet, on the network, example-network: 

    $ openstack subnet create \
  --allocation-pool start=192.0.2.10,end=192.0.2.200 \
  --network example-network \
  --subnet-range 192.0.2.0/24 \
  example-subnet

  5. Instruct the cloud users in the project to use the zone and network you have created when they add instances, ports, and floating IPs.

    Warning

    If the user creating the instance, port, or floating IP does not have permission to create record sets in the zone, or if the zone does not exist in the DNS service, the Networking service does the following:

    • creates the port with the dns_assignment field populated using the dns_domain provided.
    • does not create a record set in the DNS service.
    • logs the error, "Error publishing port data in external DNS service.".

Verification

  • Confirm that the network you created exists.

    Example
    $ openstack network show example-network
    Sample output
    +---------------------------+--------------------------------------+
| Field                     | Value                                |
+---------------------------+--------------------------------------+
| admin_state_up            | UP                                   |
| availability_zone_hints   |                                      |
| availability_zones        |                                      |
| created_at                | 2022-09-07T19:03:32Z                 |
| description               |                                      |
| dns_domain                | example.com.                         |
| id                        | 9ae5b3d5-f12c-4a67-b0e5-655d53cd4f7c |
| ipv4_address_scope        | None                                 |
| ipv6_address_scope        | None                                 |
| is_default                | None                                 |
| is_vlan_transparent       | None                                 |
| mtu                       | 1450                                 |
| name                      | example-network                      |
| port_security_enabled     | True                                 |
| project_id                | f75ec24a-d361-ab86-54c0-dfe6093245a3 |
| provider:network_type     | geneve                               |
| provider:physical_network | None                                 |
| provider:segmentation_id  | 2017                                 |
| qos_policy_id             | None                                 |
| revision_number           | 3                                    |
| router:external           | Internal                             |
| segments                  | None                                 |
| shared                    | False                                |
| status                    | ACTIVE                               |
| subnets                   | 15546c9d-6faf-43aa-83e7-b1e705eed060 |
| tags                      |                                      |
| updated_at                | 2022-09-07T19:03:43Z                 |
+---------------------------+--------------------------------------+

4.2. Integrating virtual machine instances with DNS
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Integration between the Networking service (neutron) and the DNS service (designate) enables you to automatically enable DNS whenever you create a virtual machine instance.

Prerequisites

  • The administrator has created a project for you and has provided you with a clouds.yaml file for you to access the cloud.

  • The python-openstackclient package resides on your workstation. 

    $ dnf list installed python-openstackclient
  • Your cloud administrator has provided you with the required network to use, when creating your DNS-enabled instances.

Procedure

  1. Confirm that the system OS_CLOUD variable is set for your cloud: 

    $ echo $OS_CLOUD
my_cloud

    Reset the variable if necessary: 

    $ export OS_CLOUD=my_other_cloud

    As an alternative, you can specify the cloud name by adding the --os-cloud <cloud_name> option each time you run an openstack command.

  2. Using the network that your cloud administrator has provided, create an instance.

    Example

    In this example, using the network created in the previous section, the cloud user creates an instance named my_vm: 

    $ openstack server create --image cirros-0.5.2-x86_64-disk --flavor m1.micro --nic net-id=example-network my_vm

Verification

  • Confirm that a record exists in the DNS service for the instance you created.

    Example

    In this example, the DNS service is queried for the example.com. zone: 

    $ openstack recordset list --type A example.com.
    Sample output
    +---------------+---------------------+------+------------+--------+--------+
| id            | name                | type | records    | status | action |
+---------------+---------------------+------+------------+--------+--------+
| 7b8d1be6-1b23 | my_vm.example.com.  | A    | 192.0.2.44 | ACTIVE | NONE   |
| -478a-94d5-60 |                     |      |            |        |        |
| b876dca2c8    |                     |      |            |        |        |
+---------------+---------------------+------+------------+--------+--------+

4.3. Integrating ports with DNS
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Integration between the Networking service (neutron) and the DNS service (designate) enables you to automatically add a DNS record set whenever you create a port.

Prerequisites

  • The administrator has created a project for you and has provided you with a clouds.yaml file for you to access the cloud.

  • The python-openstackclient package resides on your workstation. 

    $ dnf list installed python-openstackclient
  • Your cloud administrator has provided you with the required network to use, when creating your DNS-enabled ports.

Procedure

  1. Confirm that the system OS_CLOUD variable is set for your cloud: 

    $ echo $OS_CLOUD
my_cloud

    Reset the variable if necessary: 

    $ export OS_CLOUD=my_other_cloud

    As an alternative, you can specify the cloud name by adding the --os-cloud <cloud_name> option each time you run an openstack command.

  2. Using the zone and network that your cloud administrator has provided, create a port.

    Example

    In this example, the cloud user creates a port, my-port, with a DNS name of example-port in the network, example-network: 

    $ openstack port create --network example-network \
--dns-name example-port \
my-port

Verification

  • Confirm that a record exists in the DNS service for the port that you created.

    Example

    In this example, the DNS service is queried for the example.com. zone: 

    $ openstack recordset list --type A example.com.
    Sample output
    +---------------+---------------------------+------+-------------+--------+--------+
| id            | name                      | type | records     | status | action |
+---------------+---------------------------+------+-------------+--------+--------+
| 9ebbe94f-2442 | example-port.example.com. | A    | 192.0.2.149 | ACTIVE | NONE   |
| -4bb8-9cfa-6d |                           |      |             |        |        |
| ca1daba73f    |                           |      |             |        |        |
+---------------+---------------------------+------+-------------+--------+--------+

4.4. Integrating floating IPs with DNS
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Integration between the Networking service (neutron) and the DNS service (designate) enables you to automatically add a DNS record set whenever you create a floating IP.

Prerequisites

  • The administrator has created a project for you and has provided you with a clouds.yaml file for you to access the cloud.

  • The python-openstackclient package resides on your workstation. 

    $ dnf list installed python-openstackclient
  • Your cloud administrator has provided you with the required external network to use, when creating your DNS-enabled floating IPs.

Procedure

  1. Confirm that the system OS_CLOUD variable is set for your cloud: 

    $ echo $OS_CLOUD
my_cloud

    Reset the variable if necessary: 

    $ export OS_CLOUD=my_other_cloud

    As an alternative, you can specify the cloud name by adding the --os-cloud <cloud_name> option each time you run an openstack command.

  2. Using the zone and the external network that your cloud administrator has provided, create a floating IP.

    Example

    In this example, the cloud user creates a floating IP with a DNS name, example-fip, in the network, public: 

    $ openstack floating ip create --dns-name example-fip \
--dns-domain example.com. \
public

Verification

  • Confirm that a record exists in the DNS service for the floating IP that you created.

    Example

    In this example, the DNS service is queried for the example.com. zone: 

    $ openstack recordset list --type A example.com.
    Sample output
    +---------------+--------------------------+------+-------------+--------+--------+
| id            | name                     | type | records     | status | action |
+---------------+--------------------------+------+-------------+--------+--------+
| e1eca823-169d | example-fip.example.com. | A    | 192.0.2.106 | ACTIVE | NONE   |
| -4d0a-975e-91 |                          |      |             |        |        |
| a9907ec0c1    |                          |      |             |        |        |
+---------------+--------------------------+------+-------------+--------+--------+
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