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Michael_K_15546's avatar
Michael_K_15546
Icon for Nimbostratus rankNimbostratus
May 19, 2014

How can the F5 inform a node it is about to become the primary active node?

I have a collection of nodes living behind an F5 BIG-IP Link Controller. One subset of these nodes needs to be configured such that all incoming requests (probably on a certain port) are directed to a single active node. The other nodes in this subset are idle until needed for failover. If the F5 finds that the 'primary' node is dead/unresponsive, then it should choose another node from this group and make it active and direct all new incoming traffic to it.

 

This seems pretty basic, but what I haven't been able to figure out is that I want to 'notify' the node if it is about to become the primary/active node. These nodes will have processes that should only be running on the single active node. So if a node is about to become the single active node, can the F5 call a predetermined URL on the node which will inform it to start up these processes and prepare for incoming traffic?

 

I don't know if this is best solved with iRules, or iControl, or ?

 

Thanks! Mike

 

application delivery
devops
iRules

2 Replies

  • Eric_St__John's avatar
    Eric_St__John
    Icon for Employee rankEmployee
    May 19, 2014

    You could solve this with an external monitor. You could edit the code at the following location, adding a curl command after the "else" to call the host and URI that starts the services.

     

    HTTPMonitor_cURL_BasicGET

     

    Eric

     

  • Michael_K_15546's avatar
    Michael_K_15546
    Icon for Nimbostratus rankNimbostratus
    May 21, 2014

    Thanks Eric.

     

    So the monitor will monitor the nodes in the pool and you are saying if the health check call for one fails then I could call the URL to start services on the next node to be come the active node?

     

    How would I know which secondary node the F5 is going to pick to become the new primary? (So I can call it to tell it to start its processes)

     

    Thanks, Mike