LB::status pool checking the status of FQDN member

[SanjayP]

Does LB::status pool syntax support to check the status of FQDN member? Need to setup iRule to check the status of Azure based application server member having dynamic IP address and take persistence decision.

[Dario_Garrido]

Hello Sanjay.

Sure, you can configure ephemeral pools.

https://techdocs.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/ltm-implementations-12-1-0/25.html

Take into account that your DNS servers should give a whole set of IP members available, a round-robin response configuration is not allowed.

Regards,

Dario.

[SanjayP]

Hi Dario, ​

Thanks. I was actually looking for an option to return the status of FQDN member using

​LB::status pool. It appears LB::status only have option of using IP address of the member but not the FQDN. so, I still don't have a working a solution.

​https://clouddocs.f5.com/api/irules/LB__status.html

[Dario_Garrido]

Now I catched your point.

Well, there is no way to check pool members IPs during the iRule execution.

But if the loadbalancing decision takes place, you have the chance to figure out the IP using:

https://clouddocs.f5.com/api/irules/LB__server.html

Another chance will be to use a periodic iCall to populate one data-group with the list of all IP used in the ephemeral pool.

​Regards,

Dario.

[SanjayP]

Ok. I wanted to check the status of member before load balancing decision happens, to make peristence. Also, just returning IP won't work, it needs to check it's health using custom Http monitor applied at the pool level. So LB::status pool member helps a lot.

I will look into icall. I'm also thinking to use RESOLVE::lookup ​option. Will dig further. Thanks!

[Dario_Garrido]

Sure, but take into account this:

"Note: The results for all query types should be cached according to the Time To Live on the response. Subsequent calls using RESOLV::lookup will use the cache."

Regards,

Dario.