OVN as a Provider Driver for Octavia

Octavia has integrated support for provider drivers where any third party Load Balancer driver can be integrated with Octavia. Functionality related to this has been developed in OVN and now OVN can now be supported as a provider driver for Octavia.

The OVN Provider driver has a few advantages when used as a provider driver for Octavia over Amphora, like:

  • OVN can be deployed without VMs, so there is no additional overhead as is required currently in Octavia when using the default Amphora driver.

  • OVN Load Balancers can be deployed faster than default Load Balancers in Octavia (which use Amphora currently) because of no additional deployment requirement.

  • Since OVN supports virtual networking for both VMs and containers, OVN as a Load Balancer driver can be used succesfully with Kuryr Kubernetes[1].

Limitations of the OVN Provider Driver

OVN has its own set of limitations when considered as an Load Balancer driver. These include:

  • OVN currently supports TCP and UDP, so Layer-7 based load balancing is not possible with OVN.

  • While Health Checks are now available in OVN, they are not currently implemented in OVN’s Provider Driver for Octavia.

  • There are currently no Health Monitors in OVN’s Provider Driver for Octavia. Therefore Health Checking is not possible with OVN.

  • Currently, the OVN Provider Driver supports a 1:1 protocol mapping between Listeners and associated Pools, i.e. a Listener which can handle TCP protocols can only be used with pools associated to the TCP protocol. Pools handling UDP protocols cannot be linked with TCP based Listeners. This limitation will be handled in an upcoming core OVN release.

  • IPv6 support is not tested by Tempest.

  • Mixed IPv4 and IPv6 members are not supported.

  • Only the SOURCE_IP_PORT load balancing algorithm is supported, others like ROUND_ROBIN and LEAST_CONNECTIONS are not currently supported.

  • Octavia flavors are not supported.

Creating an OVN based Load Balancer

The OVN provider driver can be tested out on DevStack using the configuration options in:

#
# Sample DevStack local.conf.
#
# This sample file is intended to be used for your typical DevStack environment
# that's running all of OpenStack on a single host.
#
# It will enable the use of OVN as Octavia's Provider driver.
#

[[local|localrc]]

DATABASE_PASSWORD=password
RABBIT_PASSWORD=password
SERVICE_PASSWORD=password
SERVICE_TOKEN=password
ADMIN_PASSWORD=password
SERVICE_PASSWORD=$ADMIN_PASSWORD

# Logging
# -------

# By default ``stack.sh`` output only goes to the terminal where it runs.  It can
# be configured to additionally log to a file by setting ``LOGFILE`` to the full
# path of the destination log file.  A timestamp will be appended to the given name.
LOGFILE=$DEST/logs/stack.sh.log

# Old log files are automatically removed after 7 days to keep things neat.  Change
# the number of days by setting ``LOGDAYS``.
LOGDAYS=2

# Nova logs will be colorized if ``SYSLOG`` is not set; turn this off by setting
# ``LOG_COLOR`` false.
#LOG_COLOR=False

# Enable OVN
Q_AGENT=ovn
Q_ML2_PLUGIN_MECHANISM_DRIVERS=ovn,logger
Q_ML2_PLUGIN_TYPE_DRIVERS=local,flat,vlan,geneve
Q_ML2_TENANT_NETWORK_TYPE="geneve"

# Enable OVN services
enable_service ovn-northd
enable_service ovn-controller
enable_service q-ovn-metadata-agent

# Use Neutron
enable_service q-svc

# Disable Neutron agents not used with OVN.
disable_service q-agt
disable_service q-l3
disable_service q-dhcp
disable_service q-meta

# Enable services, these services depend on neutron plugin.
enable_plugin neutron https://opendev.org/openstack/neutron
enable_service q-trunk
enable_service q-dns
#enable_service q-qos

# Enable octavia tempest plugin tests
enable_plugin octavia-tempest-plugin https://opendev.org/openstack/octavia-tempest-plugin
disable_service horizon

# Cinder (OpenStack Block Storage) is disabled by default to speed up
# DevStack a bit. You may enable it here if you would like to use it.
disable_service cinder c-sch c-api c-vol

# A UUID to uniquely identify this system.  If one is not specified, a random
# one will be generated and saved in the file 'ovn-uuid' for re-use in future
# DevStack runs.
#OVN_UUID=

# If using the OVN native layer-3 service, choose a router scheduler to
# manage the distribution of router gateways on hypervisors/chassis.
# Default value is leastloaded.
#OVN_L3_SCHEDULER=leastloaded

# Whether or not to build custom openvswitch kernel modules from the ovs git
# tree. This is enabled by default.  This is required unless your distro kernel
# includes ovs+conntrack support.  This support was first released in Linux 4.3,
# and will likely be backported by some distros.
#OVN_BUILD_MODULES=False

# If the admin wants to enable this chassis to host gateway routers for
# external connectivity, then set ENABLE_CHASSIS_AS_GW to True.
# Then devstack will set ovn-cms-options with enable-chassis-as-gw
# in Open_vSwitch table's external_ids column.
# If this option is not set on any chassis, all the of them with bridge
# mappings configured will be eligible to host a gateway.
ENABLE_CHASSIS_AS_GW=True

# If you wish to use the provider network for public access to the cloud,
# set the following
#Q_USE_PROVIDERNET_FOR_PUBLIC=True

# Create public bridge
OVN_L3_CREATE_PUBLIC_NETWORK=True

# This needs to be equalized with Neutron devstack
PUBLIC_NETWORK_GATEWAY="172.24.4.1"

# Octavia configuration
OCTAVIA_NODE="api"
DISABLE_AMP_IMAGE_BUILD=True
enable_plugin barbican https://opendev.org/openstack/barbican
enable_plugin octavia https://opendev.org/openstack/octavia
enable_plugin octavia-dashboard https://opendev.org/openstack/octavia-dashboard
LIBS_FROM_GIT+=python-octaviaclient
enable_service octavia
enable_service o-api
enable_service o-hk
enable_service o-da
disable_service o-cw
disable_service o-hm

# OVN octavia provider plugin
enable_plugin ovn-octavia-provider https://opendev.org/openstack/ovn-octavia-provider

[[post-config|$NOVA_CONF]]
[scheduler]
discover_hosts_in_cells_interval = 2

Kindly note that the configuration allows the user to create Load Balancers of both Amphora and OVN types.

Once the DevStack run is complete, the user can create a load balancer in Openstack:

$ openstack loadbalancer create --vip-network-id public --provider ovn
+---------------------+--------------------------------------+
| Field               | Value                                |
+---------------------+--------------------------------------+
| admin_state_up      | True                                 |
| created_at          | 2018-12-13T09:08:14                  |
| description         |                                      |
| flavor              |                                      |
| id                  | 94e7c431-912b-496c-a247-d52875d44ac7 |
| listeners           |                                      |
| name                |                                      |
| operating_status    | OFFLINE                              |
| pools               |                                      |
| project_id          | af820b57868c4864957d523fb32ccfba     |
| provider            | ovn                                  |
| provisioning_status | PENDING_CREATE                       |
| updated_at          | None                                 |
| vip_address         | 172.24.4.9                           |
| vip_network_id      | ee97665d-69d0-4995-a275-27855359956a |
| vip_port_id         | c98e52d0-5965-4b22-8a17-a374f4399193 |
| vip_qos_policy_id   | None                                 |
| vip_subnet_id       | 3eed0c05-6527-400e-bb80-df6e59d248f1 |
+---------------------+--------------------------------------+

The user can see the different types of loadbalancers with their associated providers as below:

+--------------------------------------+------+----------------------------------+-------------+---------------------+----------+
| id                                   | name | project_id                       | vip_address | provisioning_status | provider |
+--------------------------------------+------+----------------------------------+-------------+---------------------+----------+
| c5f2070c-d51d-46f0-bec6-dd05e7c19370 |      | af820b57868c4864957d523fb32ccfba | 172.24.4.10 | ACTIVE              | amphora  |
| 94e7c431-912b-496c-a247-d52875d44ac7 |      | af820b57868c4864957d523fb32ccfba | 172.24.4.9  | ACTIVE              | ovn      |
+--------------------------------------+------+----------------------------------+-------------+---------------------+----------+

Now we can see that OVN will show the load balancer in its loadbalancer table:

$ ovn-nbctl list load_balancer
_uuid               : c72de15e-5c2e-4c1b-a21b-8e9a6721193c
external_ids        : {enabled=True,
                       lr_ref="neutron-3d2a873b-b5b4-4d14-ac24-47a835fd47b2",
                       ls_refs="{\"neutron-ee97665d-69d0-4995-a275-27855359956a\": 1}",
                       "neutron:vip"="172.24.4.9",
                       "neutron:vip_port_id"="c98e52d0-5965-4b22-8a17-a374f4399193"}
name                : "94e7c431-912b-496c-a247-d52875d44ac7"
protocol            : tcp
vips                : {}

Next, a Listener can be created for the associated Load Balancer:

$ openstack loadbalancer listener create --protocol TCP --protocol-port /
  64015 94e7c431-912b-496c-a247-d52875d44ac7
+---------------------------+--------------------------------------+
| Field                     | Value                                |
+---------------------------+--------------------------------------+
| admin_state_up            | True                                 |
| connection_limit          | -1                                   |
| created_at                | 2018-12-13T09:14:51                  |
| default_pool_id           | None                                 |
| default_tls_container_ref | None                                 |
| description               |                                      |
| id                        | 21e77cde-854f-4c3e-bd8c-9536ae0443bc |
| insert_headers            | None                                 |
| l7policies                |                                      |
| loadbalancers             | 94e7c431-912b-496c-a247-d52875d44ac7 |
| name                      |                                      |
| operating_status          | OFFLINE                              |
| project_id                | af820b57868c4864957d523fb32ccfba     |
| protocol                  | TCP                                  |
| protocol_port             | 64015                                |
| provisioning_status       | PENDING_CREATE                       |
| sni_container_refs        | []                                   |
| timeout_client_data       | 50000                                |
| timeout_member_connect    | 5000                                 |
| timeout_member_data       | 50000                                |
| timeout_tcp_inspect       | 0                                    |
| updated_at                | None                                 |
+---------------------------+--------------------------------------+

OVN updates the Listener information in the Load Balancer table:

$ ovn-nbctl list load_balancer
_uuid               : c72de15e-5c2e-4c1b-a21b-8e9a6721193c
external_ids        : {enabled=True, "listener_21e77cde-854f-4c3e-bd8c-9536ae0443bc"="64015:", lr_ref="neutron-3d2a873b-b5b4-4d14-ac24-47a835fd47b2", ls_refs="{\"neutron-ee97665d-69d0-4995-a275-27855359956a\": 1}", "neutron:vip"="172.24.4.9", "neutron:vip_port_id"="c98e52d0-5965-4b22-8a17-a374f4399193"}
name                : "94e7c431-912b-496c-a247-d52875d44ac7"
protocol            : tcp
vips                : {}

Next, a Pool is associated with the Listener:

$ openstack loadbalancer pool create --protocol TCP --lb-algorithm /
SOURCE_IP_PORT --listener 21e77cde-854f-4c3e-bd8c-9536ae0443bc
+---------------------+--------------------------------------+
| Field               | Value                                |
+---------------------+--------------------------------------+
| admin_state_up      | True                                 |
| created_at          | 2018-12-13T09:21:37                  |
| description         |                                      |
| healthmonitor_id    |                                      |
| id                  | 898be8a2-5185-4f3b-8658-a56457f595a9 |
| lb_algorithm        | SOURCE_IP_PORT                       |
| listeners           | 21e77cde-854f-4c3e-bd8c-9536ae0443bc |
| loadbalancers       | 94e7c431-912b-496c-a247-d52875d44ac7 |
| members             |                                      |
| name                |                                      |
| operating_status    | OFFLINE                              |
| project_id          | af820b57868c4864957d523fb32ccfba     |
| protocol            | TCP                                  |
| provisioning_status | PENDING_CREATE                       |
| session_persistence | None                                 |
| updated_at          | None                                 |
+---------------------+--------------------------------------+

OVN’s Load Balancer table is modified as below:

$ ovn-nbctl list load_balancer
_uuid               : c72de15e-5c2e-4c1b-a21b-8e9a6721193c
external_ids        : {enabled=True, "listener_21e77cde-854f-4c3e-bd8c-9536ae0443bc"="64015:", lr_ref="neutron-3d2a873b-b5b4-4d14-ac24-47a835fd47b2", ls_refs="{\"neutron-ee97665d-69d0-4995-a275-27855359956a\": 1}", "neutron:vip"="172.24.4.9", "neutron:vip_port_id"="c98e52d0-5965-4b22-8a17-a374f4399193", "pool_898be8a2-5185-4f3b-8658-a56457f595a9"=""}
name                : "94e7c431-912b-496c-a247-d52875d44ac7"
protocol            : tcp
vips                : {}

Lastly, when a member is created, OVN’s Load Balancer table is complete:

$ openstack loadbalancer member create --address 10.10.10.10 /
--protocol-port 63015 898be8a2-5185-4f3b-8658-a56457f595a9
+---------------------+--------------------------------------+
| Field               | Value                                |
+---------------------+--------------------------------------+
| address             | 10.10.10.10                          |
| admin_state_up      | True                                 |
| created_at          | 2018-12-13T09:26:05                  |
| id                  | adf55e70-3d50-4e62-99fd-dd77eababb1c |
| name                |                                      |
| operating_status    | NO_MONITOR                           |
| project_id          | af820b57868c4864957d523fb32ccfba     |
| protocol_port       | 63015                                |
| provisioning_status | PENDING_CREATE                       |
| subnet_id           | None                                 |
| updated_at          | None                                 |
| weight              | 1                                    |
| monitor_port        | None                                 |
| monitor_address     | None                                 |
| backup              | False                                |
+---------------------+--------------------------------------+
$ ovn-nbctl list load_balancer
_uuid               : c72de15e-5c2e-4c1b-a21b-8e9a6721193c
external_ids        : {enabled=True, "listener_21e77cde-854f-4c3e-bd8c-9536ae0443bc"="64015:pool_898be8a2-5185-4f3b-8658-a56457f595a9", lr_ref="neutron-3d2a873b-b5b4-4d14-ac24-47a835fd47b2", ls_refs="{\"neutron-ee97665d-69d0-4995-a275-27855359956a\": 1}", "neutron:vip"="172.24.4.9", "neutron:vip_port_id"="c98e52d0-5965-4b22-8a17-a374f4399193", "pool_898be8a2-5185-4f3b-8658-a56457f595a9"="member_adf55e70-3d50-4e62-99fd-dd77eababb1c_10.10.10.10:63015"}
name                : "94e7c431-912b-496c-a247-d52875d44ac7"
protocol            : tcp
vips                : {"172.24.4.9:64015"="10.10.10.10:63015"}

[1]: https://docs.openstack.org/kuryr-kubernetes/latest/installation/services.html