Kubernetes integration with OpenStack networking
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IPv6 networking

Kuryr Kubernetes can be used with IPv6 networking. In this guide we'll show how you can create the Neutron resources and configure Kubernetes and Kuryr-Kubernetes to achieve an IPv6 only Kubernetes cluster.

Setting it up

  1. Create pods network:

    $ openstack network create pods
    +---------------------------+--------------------------------------+
    | Field                     | Value                                |
    +---------------------------+--------------------------------------+
    | admin_state_up            | UP                                   |
    | availability_zone_hints   |                                      |
    | availability_zones        |                                      |
    | created_at                | 2017-08-11T10:51:25Z                 |
    | description               |                                      |
    | dns_domain                | None                                 |
    | id                        | 4593045c-4233-4b4c-8527-35608ab0eaae |
    | ipv4_address_scope        | None                                 |
    | ipv6_address_scope        | None                                 |
    | is_default                | False                                |
    | is_vlan_transparent       | None                                 |
    | mtu                       | 1450                                 |
    | name                      | pods                                 |
    | port_security_enabled     | True                                 |
    | project_id                | 90baf12877ba49a786419b2cacc2c954     |
    | provider:network_type     | vxlan                                |
    | provider:physical_network | None                                 |
    | provider:segmentation_id  | 21                                   |
    | qos_policy_id             | None                                 |
    | revision_number           | 2                                    |
    | router:external           | Internal                             |
    | segments                  | None                                 |
    | shared                    | False                                |
    | status                    | ACTIVE                               |
    | subnets                   |                                      |
    | tags                      | []                                   |
    | updated_at                | 2017-08-11T10:51:25Z                 |
    +---------------------------+--------------------------------------+
  2. Create the pod subnet:

    $ openstack subnet create --network pods --no-dhcp \
          --subnet-range fd10:0:0:1::/64 \
          --ip-version 6 \
          pod_subnet
    +-------------------------+-------------------------------------------+
    | Field                   | Value                                     |
    +-------------------------+-------------------------------------------+
    | allocation_pools        | fd10:0:0:1::2-fd10::1:ffff:ffff:ffff:ffff |
    | cidr                    | fd10:0:0:1::/64                           |
    | created_at              | 2017-08-11T17:02:20Z                      |
    | description             |                                           |
    | dns_nameservers         |                                           |
    | enable_dhcp             | False                                     |
    | gateway_ip              | fd10:0:0:1::1                             |
    | host_routes             |                                           |
    | id                      | eef12d65-4d02-4344-b255-295f9adfd4e9      |
    | ip_version              | 6                                         |
    | ipv6_address_mode       | None                                      |
    | ipv6_ra_mode            | None                                      |
    | name                    | pod_subnet                                |
    | network_id              | 4593045c-4233-4b4c-8527-35608ab0eaae      |
    | project_id              | 90baf12877ba49a786419b2cacc2c954          |
    | revision_number         | 0                                         |
    | segment_id              | None                                      |
    | service_types           |                                           |
    | subnetpool_id           | None                                      |
    | tags                    | []                                        |
    | updated_at              | 2017-08-11T17:02:20Z                      |
    | use_default_subnet_pool | None                                      |
    +-------------------------+-------------------------------------------+
  3. Create services network:

    $ openstack network create services
    +---------------------------+--------------------------------------+
    | Field                     | Value                                |
    +---------------------------+--------------------------------------+
    | admin_state_up            | UP                                   |
    | availability_zone_hints   |                                      |
    | availability_zones        |                                      |
    | created_at                | 2017-08-11T10:53:36Z                 |
    | description               |                                      |
    | dns_domain                | None                                 |
    | id                        | 560df0c2-537c-41c0-b22c-40ef3d752574 |
    | ipv4_address_scope        | None                                 |
    | ipv6_address_scope        | None                                 |
    | is_default                | False                                |
    | is_vlan_transparent       | None                                 |
    | mtu                       | 1450                                 |
    | name                      | services                             |
    | port_security_enabled     | True                                 |
    | project_id                | 90baf12877ba49a786419b2cacc2c954     |
    | provider:network_type     | vxlan                                |
    | provider:physical_network | None                                 |
    | provider:segmentation_id  | 94                                   |
    | qos_policy_id             | None                                 |
    | revision_number           | 2                                    |
    | router:external           | Internal                             |
    | segments                  | None                                 |
    | shared                    | False                                |
    | status                    | ACTIVE                               |
    | subnets                   |                                      |
    | tags                      | []                                   |
    | updated_at                | 2017-08-11T10:53:37Z                 |
    +---------------------------+--------------------------------------+
  4. Create services subnet. We reserve the first half of the subnet range for the VIPs and the second half for the loadbalancer vrrp ports :

    $ openstack subnet create --network services --no-dhcp \
          --gateway fd10:0:0:2:0:0:0:fffe \
          --ip-version 6 \
          --allocation-pool start=fd10:0:0:2:0:0:0:8000,end=fd10:0:0:2:0:0:0:fffd \
          --subnet-range fd10:0:0:2::/112 \
          service_subnet
    +-------------------------+--------------------------------------+
    | Field                   | Value                                |
    +-------------------------+--------------------------------------+
    | allocation_pools        | fd10:0:0:2::8000-fd10:0:0:2::fffd    |
    | cidr                    | fd10:0:0:2::/112                     |
    | created_at              | 2017-08-14T19:08:34Z                 |
    | description             |                                      |
    | dns_nameservers         |                                      |
    | enable_dhcp             | False                                |
    | gateway_ip              | fd10:0:0:2::fffe                     |
    | host_routes             |                                      |
    | id                      | 3c53ff94-40e2-4399-bc45-6e210f1e8064 |
    | ip_version              | 6                                    |
    | ipv6_address_mode       | None                                 |
    | ipv6_ra_mode            | None                                 |
    | name                    | service_subnet                       |
    | network_id              | 560df0c2-537c-41c0-b22c-40ef3d752574 |
    | project_id              | 90baf12877ba49a786419b2cacc2c954     |
    | revision_number         | 0                                    |
    | segment_id              | None                                 |
    | service_types           |                                      |
    | subnetpool_id           | None                                 |
    | tags                    | []                                   |
    | updated_at              | 2017-08-14T19:08:34Z                 |
    | use_default_subnet_pool | None                                 |
    +-------------------------+--------------------------------------+
  5. Create a router:

    $ openstack router create k8s-ipv6
    +-------------------------+--------------------------------------+
    | Field                   | Value                                |
    +-------------------------+--------------------------------------+
    | admin_state_up          | UP                                   |
    | availability_zone_hints |                                      |
    | availability_zones      |                                      |
    | created_at              | 2017-08-11T13:17:10Z                 |
    | description             |                                      |
    | distributed             | False                                |
    | external_gateway_info   | None                                 |
    | flavor_id               | None                                 |
    | ha                      | False                                |
    | id                      | f802a968-2f83-4006-80cb-5070415f69bf |
    | name                    | k8s-ipv6                             |
    | project_id              | 90baf12877ba49a786419b2cacc2c954     |
    | revision_number         | None                                 |
    | routes                  |                                      |
    | status                  | ACTIVE                               |
    | tags                    | []                                   |
    | updated_at              | 2017-08-11T13:17:10Z                 |
    +-------------------------+--------------------------------------+
  6. Add the router to the pod subnet:

    $ openstack router add subnet k8s-ipv6 pod_subnet
  7. Add the router to the service subnet:

    $ openstack router add subnet k8s-ipv6 service_subnet
  8. Modify Kubernetes API server command line so that it points to the right CIDR:

    --service-cluster-ip-range=fd10:0:0:2::/113

    Note that it is /113 because the other half of the /112 will be used by the Octavia LB vrrp ports.

  9. Follow the k8s_lb_reachable guide but using IPv6 addresses instead for the host Kubernetes API. You should also make sure that the Kubernetes API server binds on the IPv6 address of the host.

Troubleshooting

  • Pods can talk to each other with IPv6 but they can't talk to services.

    This means that most likely you forgot to create a security group or rule for the pods to be accessible by the service CIDR. You can find an example here:

    $ openstack security group create service_pod_access_v6
    +-----------------+-------------------------------------------------------------------------------------------------------------------------------------------------------+
    | Field           | Value                                                                                                                                                 |
    +-----------------+-------------------------------------------------------------------------------------------------------------------------------------------------------+
    | created_at      | 2017-08-16T10:01:45Z                                                                                                                                  |
    | description     | service_pod_access_v6                                                                                                                                 |
    | id              | f0b6f0bd-40f7-4ab6-a77b-3cf9f7cc28ac                                                                                                                  |
    | name            | service_pod_access_v6                                                                                                                                 |
    | project_id      | 90baf12877ba49a786419b2cacc2c954                                                                                                                      |
    | revision_number | 2                                                                                                                                                     |
    | rules           | created_at='2017-08-16T10:01:45Z', direction='egress', ethertype='IPv4', id='bd759b4f-c0f5-4cff-a30a-3cd8544d2822', updated_at='2017-08-16T10:01:45Z' |
    |                 | created_at='2017-08-16T10:01:45Z', direction='egress', ethertype='IPv6', id='c89c3f3e-a326-4902-ba26-5315e2d95320', updated_at='2017-08-16T10:01:45Z' |
    | updated_at      | 2017-08-16T10:01:45Z                                                                                                                                  |
    +-----------------+-------------------------------------------------------------------------------------------------------------------------------------------------------+
    
    $ openstack security group rule create --remote-ip fd10:0:0:2::/112 \
         --ethertype IPv6 f0b6f0bd-40f7-4ab6-a77b-3cf9f7cc28ac
    +-------------------+--------------------------------------+
    | Field             | Value                                |
    +-------------------+--------------------------------------+
    | created_at        | 2017-08-16T10:04:57Z                 |
    | description       |                                      |
    | direction         | ingress                              |
    | ether_type        | IPv6                                 |
    | id                | cface77f-666f-4a4c-8a15-a9c6953acf08 |
    | name              | None                                 |
    | port_range_max    | None                                 |
    | port_range_min    | None                                 |
    | project_id        | 90baf12877ba49a786419b2cacc2c954     |
    | protocol          | tcp                                  |
    | remote_group_id   | None                                 |
    | remote_ip_prefix  | fd10:0:0:2::/112                     |
    | revision_number   | 0                                    |
    | security_group_id | f0b6f0bd-40f7-4ab6-a77b-3cf9f7cc28ac |
    | updated_at        | 2017-08-16T10:04:57Z                 |
    +-------------------+--------------------------------------+

    Then remember to add the new security groups to the comma-separated pod_security_groups setting in the section [neutron_defaults] of /etc/kuryr/kuryr.conf