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playfair039_320's avatar
playfair039_320
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Mar 28, 2018

Persistence

I have a pool of 8 tomcat servers that connect to a group of 2 downstream application servers. I use destination address persistence so that it doesn't matter which server and the only cause of a fai...
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playfair039_320's avatar
playfair039_320
Icon for Nimbostratus rankNimbostratus
Apr 06, 2018

A solution here was to use source_addr persistence - only gets inserted when there's been a failover and check if there is an active persistence session before directing the tomcat instances to an application server. 

when request {
  set persistenceRecord [persist lookup source_addr [IP::client_addr]]
  if { $persistenceRecord eq "" }{
    if {([class match [IP::client_addr] equals dg1]) && ([active_members pool] > 1 )}{
      pool pool member 1.1.1.1 [port]
     } elseif {([class match [IP::client_addr] equals dg2]) && ([active_members pool] > 1 )} {
      pool pool member 2.2.2.2 [port]
     } else {
     pool pool
     persist source_addr ...

Because a persistence record only gets inserted if/when we hit the default else of that block, we maintain those persistence sessions and never fail back + we only ever get into the block if no persistence records exist to begin with.