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danA's avatar
danA
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Sep 26, 2023
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Interrogate Pool Member Priority Group from iRule

Hi,

Is it possible to programatically identifiy the priority group of a pool member from within an iRule? I'd like to be able to combine that information with the results of active_members to be able to present a status of which group(s) are currently active.

Thanks,

Dan

"priority group"
application delivery
devops
  • Paulius's avatar
    Paulius
    Sep 27, 2023

    danA Sadly, I'm not aware of a native way of providing the priority group number in an HTTP header field so that the CDN can see this as a degraded virtual server. I believe the better option here would be to have each pool member in each priority group have a unique response to a specific HTTP path so if the CDN sees a certain response it will see it as a degraded VS. For instance priority 0 pool members in path /healthmonitor could have a response string of "Priority 0 active" and then the pool members in 100 could have /healthmonitor with a response of "Priority 100 active" which would then kick off a degraded event from the CDN side of things.

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  • Paulius's avatar
    Paulius
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    Sep 27, 2023

    danA Are you attempting to log this information or what exactly are you attempting to do with this information?

  • danA's avatar
    danA
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    Sep 27, 2023

    Paulius 

    I'm building an iRule which will reply to a CDN health check about the health of the service.

    The pool in question has two sets of servers, priority 0 and priority 100. App level health checks inform the LTM which members are active. If the servers in one group are active, we consider that datacenter degraded and would like that to be accounted for in the health check.

    • Paulius's avatar
      Paulius
      Icon for MVP rankMVP
      Sep 27, 2023

      danA Sadly, I'm not aware of a native way of providing the priority group number in an HTTP header field so that the CDN can see this as a degraded virtual server. I believe the better option here would be to have each pool member in each priority group have a unique response to a specific HTTP path so if the CDN sees a certain response it will see it as a degraded VS. For instance priority 0 pool members in path /healthmonitor could have a response string of "Priority 0 active" and then the pool members in 100 could have /healthmonitor with a response of "Priority 100 active" which would then kick off a degraded event from the CDN side of things.

  • danA's avatar
    danA
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    Sep 27, 2023

    Thanks - that's what I figured, but thought I'd check. I want to rely on the built-in health check to determine the pool member health and not have to ask each server when the rule fires. I'll pull in the server/group mapping either from a data group or a sideband/HSSR request as needed.