UDP Support¶

Alternatives¶

Introduce a new UDP driver based on LVS or other Loadbalancer engines. Then find a way to fix the gap of the current Octavia data models which have a strong relationship with HTTP which based on TCP.

Provide a new driver provider framework to change the amphorae backend from haproxy to some other load balancer engines, for example, if we introduce LVS driver, we may just support the simple L7 functions with LVS, as it’s a risk to change provider from existing haproxy-based amphora instances to LVS ones. If possible, we need to limit the API to not support fields/resources if the backend driver is LVS, such as “insert_headers” in Listener, L7Policies, L7Rules and etc, a series fields/resources that related to L7 layer. The all things are to match the real ability of backend. That means all the configuration of L7 resources will be ignored or translate to LVS configuration if the backend is LVS. For other load balancer engines which support UDP, such as f5/nginx, we may also need to do this.

Combining the 2 load balancer engines for a simple reference implementation, LVS would only support the L4 layer LB, and haproxy would provide the L7 LB functionality which is more specific and detailed. For other engines like f5/nginx, Octavia can directly pass the UDP parameters to backend. This is very good for the community environment. Then Octavia may support more powerful and complex LoadBalancing solutions.

Data model impact¶

There may not be any data model changes, this spec just allows a user to input the udp protocol to create/update the Listener and Pool resources. So here, just extend the SUPPORTED_PROTOCOLS to add the value PROTOCOL_UDP.

SUPPORTED_PROTOCOLS = (PROTOCOL_TCP, PROTOCOL_HTTPS, PROTOCOL_HTTP,
                       PROTOCOL_TERMINATED_HTTPS, PROTOCOL_PROXY,
                       PROTOCOL_UDP)

Also add a record into the table protocol for PROTOCOL_UDP.

As LVS only operates in Layer 4, there are some conflicts with current Octavia data models. There are some limitation below:

1. No L7 policies allowed.

2. For session persistence, this spec will intro persistence_timeout (sec) and persistence_granularity (subnet mask) [11] in the virtual server configuration. The function will be based on the LVS. With no session persistence specified, LVS will be configured with a persistence_timeout of 0. There are two valid session persistence options for UDP (if session persistence is specified), SOURCE_IP and ONE_PACKET_SCHEDULING.

3. Intro a ‘UDP_CONNECT’ type for UDP in healthmonitor, for the simple, only check the UDP port is open by nc command. And for current API of healthmonitor, we need to make clear the meaning of LVS with the current healthmonitor API like the mapping below

   Option Mapping Healthmonitor->LVS	Healthmonitor Description	Keepalived LVS Description
   delay -> delay_loop	Set the time in seconds, between sending probes to members.	Delay timer for service polling.
   max_retires_down -> retry	Set the number of allowed check failure before changing the operating status of the member to ERROR.	Number of retries before fail.
   timeout -> delay_before_retry	Set the maximum time, in seconds, that a monitor waits to connect before it times out. This value must be less than the delay value.	delay before retry (default 1 unless otherwise specified)

4. For UDP load balancing, we can support the same algorithms at first. Such as SOURCE_IP(sh), ROUND_ROBIN(rr) and LEAST_CONNECTIONS(lc).

REST API impact¶

• Allow the protocol fields to accept udp.

• Allow the healthmonitor.type field to accept UDP type values.

• Add some fields to session_persistence that are specific to UDP though SOURCE_IP type and a new type ONE_PACKET_SCHEDULING.

Create/Update Listener Request:

POST/PUT /v2.0/lbaas/listeners
{
    "listener": {
        "admin_state_up": true,
        "connection_limit": 100,
        "description": "listener one",
        "loadbalancer_id": "a36c20d0-18e9-42ce-88fd-82a35977ee8c",
        "name": "listener1",
        "protocol": "UDP",
        "protocol_port": "18000"
    }
}

Create/Update Pool Request

SOURCE_IP type case:

POST/PUT /v2.0/lbaas/pools

{
    "pool": {
        "admin_state_up": true,
        "description": "simple pool",
        "lb_algorithm": "ROUND_ROBIN",
        "name": "my-pool",
        "protocol": "UDP",
        "session_persistence": {
            "type": "SOURCE_IP",
            "persistence_timeout": 60,
            "persistence_granularity": "255.255.0.0",
        }
        "listener_id": "39de4d56-d663-46e5-85a1-5b9d5fa17829",
    }
}

ONE_PACKET_SCHEDULING type case:

POST/PUT /v2.0/lbaas/pools

{
    "pool": {
        "admin_state_up": true,
        "description": "simple pool",
        "lb_algorithm": "ROUND_ROBIN",
        "name": "my-pool",
        "protocol": "UDP",
        "session_persistence": {
            "type": "ONE_PACKET_SCHEDULING"
        }
        "listener_id": "39de4d56-d663-46e5-85a1-5b9d5fa17829",
    }
}

Create/Update Health Monitor Request:

POST/PUT /v2.0/lbaas/healthmonitors

{
    "healthmonitor": {
        "name": "Good health monitor"
        "admin_state_up": true,
        "pool_id": "c5e9e801-0473-463b-a017-90c8e5237bb3",
        "delay": 10,
        "max_retries": 4,
        "max_retries_down": 4,
        "timeout": 5,
        "type": "UDP_CONNECT"
    }
}

Security impact¶

The security should be affected by the UDP server, we need to add another neutron security group rule to the existing security group to support UDP. Security impact is minimal as the keepalived/LVS will be running in the tenant traffic network namespace.

Notifications impact¶

No expected change.

Other end user impact¶

Users will be able to pass “UDP” to create/update Listener/Pool resources for UDP load balancer.

Performance Impact¶

• If enabled driver is LVS, it will have a good performance for L4 load balancing, but lack the any functionality in L7.

• As this spec introduces LVS and Haproxy working together, if users update the Listener or Pool resources in a LoadBalancer instance frequently, the loadbalancer functionality may be delayed for a while as the refresh of UDP related LVS configuration.

• As we need to add keepalived monitoring process for each UDP listeners, it is necessary to consider RAM about amphora VM instances.

Other deployer impact¶

No expected change.

Developer impact¶

No expected change.

Assignee(s)¶

zhaobo

Work Items¶

• Add/extend startup script templates for keepalived processes, including configuration.

• Extend the ability of existing amphora agent and driver to generate and control LVS by keepalived in amphora instances.

• Extend the exist Octavia V2 API to access udp parameter in Listener and pools resources.

• Extend the Loadbalancer/Listener flows to support udp loadbalancer in the particular topologies.

• Extend Octavia V2 API to accept UDP fields.

• Add the specified logic which involved into haproxy agent and the affected resource workflow in Octavia.

• Add API validation code to validate the fields of UDP cases.

• Add Unit Tests to Octavia.

• Add API functional tests.

• Add scenario tests into octavia tempest plugin.

• Update CLI and Octavia-dashboard to support UDP fields input.

• Documentation work.