Forum Discussion

Hendel's avatar
Hendel
Icon for Nimbostratus rankNimbostratus
Jan 31, 2023

Insert header when item added to ramcache

Haven't been in here for a looong time... :-7

Trying to store a header value received from pool member in a new header as that item is added to the ramcache (so it'll be present when that item is subsequently retrieved from the ramcache), but using CACHE::header insert NewHeader $value in the CACHE_UPDATE event doesn't seem to work (13.1) - has anyone used it successfully? 

application delivery
  • Leslie_Hubertus's avatar
    Leslie_Hubertus
    Ret. Employee
    Feb 02, 2023

    Hey Hendel  - welcome back! I see nobody has come to answer this yet, so I'll see if one of my colleagues can come in to help. 

  • Hendel's avatar
    Hendel
    Icon for Nimbostratus rankNimbostratus
    Feb 06, 2023

    Thanks, I'd appreciate that - seems like this ought to be pretty simple, so I'm probably just holding the wrong end of the metaphorical wrench or something

     

  • JRahm's avatar
    JRahm
    Icon for Admin rankAdmin
    Feb 06, 2023

    Hi Hendel, I haven't done much with the cache in iRules, but your format for setting appears to be correct. That said, can you post a sanitized version of your iRule and whether you have any other iRules or policies that might be interfering? How are you validating that it is not working? Could use CACHE::trace to see if anything is at least being set by the system before hitting a tcpdump on the wire.

    • Hendel's avatar
      Hendel
      Icon for Nimbostratus rankNimbostratus
      Feb 07, 2023

      There aren't any other rules or policies. I'd tried both insert and replace, but the logging in CACHE_RESPONSE never showed any effect from either of the UPDATE commands.

      when CACHE_UPDATE {
  CACHE::header insert X-LTM-Cached $cache
  # CACHE::header replace Cache-Control $cache
}
when CACHE_RESPONSE {
  log local0. "[IP::client_addr] path:$path cache:$cache [CACHE::headers]"
}
when HTTP_REQUEST {
  set path [string tolower [HTTP::path]]
  if { !($path ends_with ".js") } {
    CACHE::disable
  } else {
      HTTP::uri [HTTP::path]
      CACHE::enable
  }
}
when HTTP_RESPONSE {
  set cache [HTTP::header value Cache-Control]
  HTTP::header replace Cache-Control public
}
      • JRahm's avatar
        JRahm
        Icon for Admin rankAdmin
        Feb 07, 2023

        I updated the formatting to make it a little easier to read through...let me reach out internally to see if anyone has worked with the cache commands before, I'm not quite sure what the flow should be here.

    • Hendel's avatar
      Hendel
      Icon for Nimbostratus rankNimbostratus
      Feb 08, 2023

      I'm able to log CACHE::headers when I retrieve objects from the cache, it's just that they only come out with all of their original headers/values as sent by the pool member, not the ones I was trying to insert and/or modify as they went in to the cache.

      • John_Alam's avatar
        John_Alam
        Icon for Employee rankEmployee
        Feb 08, 2023

        i used this version and was able to change the headers Cache-Control.  I was also able to insert headers.  No dynamic values though.

         

        when CACHE_UPDATE {
    CACHE::header insert X-LTM-Cached "test"
    CACHE::header replace Cache-Control "private"
    log local0. "Cache update- path:$path cache: [CACHE::headers]"
}

         

        But you have to invalidate the cache before every expected change of behavior.  You do that from the CLI with this command:  

         

        tmsh delete /ltm profile ramcache optimized-caching

         

         and reload page twice.  First reload will not have the cached version.

        HTH