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JohnG_365824's avatar
JohnG_365824
Icon for Nimbostratus rankNimbostratus
Sep 21, 2018

Probing multiple pool members for a successful request.

What we want to achieve here is to have 2x active pool members, each containing different data sets but part of a single VS.

 

Requests will be sent to both servers. (looking for a username for example) and only one of the servers will contain the data. The requests will be sent to both servers. The server without the data will give an error (4XX HTTP status code) The server with the data will give a success (2XX HTTP status)

 

The F5 should then take the data from the successful server and send it to the client.

 

Is this possible?

 

application delivery
iRules
LTM

3 Replies

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  • Chris_Grant's avatar
    Chris_Grant
    Icon for Employee rankEmployee
    Sep 21, 2018

    That's a fascinating (and unexpected) use case. I'm pretty sure it's probably doable, but it would need some serious iRule skills. I would recommend you talk to our professional services group if you don't get something from the community here. They can likely help you out.

     

  • Simon_Blakely's avatar
    Simon_Blakely
    Icon for Employee rankEmployee
    Sep 24, 2018

    You should investigate the SIDEBAND irule commands.

     

    The way I would do it is to extract a relevant key from the request, have a light "query" request that you sideband with the key to both the pool members to identify the pool member that holds the response, then pass the heavyweight actual request to the identified pool member to get the complete response.

     

  • Simon_Blakely's avatar
    Simon_Blakely
    Icon for Employee rankEmployee
    Sep 24, 2018

    An easier solution is HTTP::retry

     

    There is an example on that page that should do what you want without too much modification.

     

    If you are making a POST request you need an HTTP::collect to get the payload for resubmisssion.