[openstack-dev] LBaaS Pool Member API

Ravi Chunduru ravivsn at gmail.com
Sun Jan 27 21:51:40 UTC 2013

I am posting this question on behalf of Srini as per his request that his
mail got rejected. Discard if original mail is received.


I am not sure this question was answered earlier.

Pool Member API as defined http://wiki.openstack.org/Quantum/LBaaS/API_1.0 =
 is shown below for easy reference.

"address" parameter is IP address of VM that is expected to take up the loa=

In Openstack environment,  application VMs'  IP addresses are assigned dyna=
mically by Quantum IPAM.    This API (Add Pool member) seems to be expectin=
g IP address.   Admin configuring LB may not know the IP address. Moreover =
these application VMs are brought up dynamically upon the load and also bro=
ught down when load goes down.  That is, pool members need to be added or r=
emoved dynamically.   So, my question is who would be calling this API? It =
can't  be through Horizon pages  as user don't know the IP addresses.

To make client and GUI development easier,  is it not good to take "VM grou=
p"  instead of "address"?     Internally, quantum can figure out the IP add=
resses of VMs in the VM group (by monitoring VM bring up/down events)  and =
program the LB device dynamically with the IP addresses.

My understanding is that in openstack world,  VM grouping is typically achi=
eved using "metadata" that is passed to 'nova boot'.    "Role" metadata key=
 is normally used to represent the role of VM.  If that is indeed the case,=
  "role" value can be taken as input to this API (Add Pool Member) function=
.    For example, tenant can use  VM group called "Web-Server-Group-10".  W=
hen tenant brings up webserver VM that need to participate in taking up the=
 load,  it can be given "Web-Server-Group-10" as "role".    Tenant can also=
 configure the LB with "Web-Server-Group-10" as pool member.    As long as =
quantum LB plugin has intelligence to enumerate the IP addresses of VMs tha=
t are brought up with "Web-Server-Group_10",  it should be able to configur=
e load balancer device using appropriate LB drivers.

I am not sure whether this is a valid concern.  If it is not, can somebody =
point me to right place on how this problem is solved?

            Create Pool Members
Verb    URI     Description
POST    /v1.0/members   Add members to pools.

            Normal Response Code(s): 202
            Error Response Code(s): serviceFault (500), serviceUnavailable =
(503), unauthorized (401), badRequest (400), overLimit (413)
            When a member is created, it is assigned a unique identifier th=
at can be used for mutating operations such as changing the admin_state or =
the weight of a member, or removing the member from the pool.
            The caller of this operation must specify at least the followin=
g attributes of the Pool:
*       tenant_id: only required if the caller has an admin role and wants =
to create a pool for another tenant.
*       address: the IP address of the pool member on the pool's network.
*       port: The port on which the pool member listens for requests or con=
*       pool_id: The pool to which the member belongs.


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