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AlexBCT's avatar
AlexBCT
Icon for Cumulonimbus rankCumulonimbus
May 12, 2021

iStats Gauge and String options - any experience?

Hi,   When working with iStats, there is an option to configure the metrics as a Counter, Gauge and String. As far as I understand it, the Gauge gives an average value of all values given to it,...
application delivery
iRules
LTM
  • Dario_Garrido's avatar
    Dario_Garrido
    May 24, 2021

    Yes, it's exactly as you said.

    ​An example of decrementing a gauge value is:

    istats incr "uri /api gauge curr_reqs" -- -3

    Regards,

    Dario.

Dario_Garrido's avatar
Dario_Garrido
Icon for MVP rankMVP

Hello AlexBCT.

Counter, Gauge and String are just measure types, not a format types.

String is a text, and the difference between counter and gauge is bit sutil (similar to counter and gauge difference in SNMP).

F5-BIGIP-LOCAL-MIB::ltmServerSslMaxActiveHandshake."/Common/crypto-client-default-serverssl" = Gauge32: 0
F5-BIGIP-LOCAL-MIB::ltmServerSslStatHandshakeFailures."/Common/serverssl" = Counter64: 0

Counters only increase, but gauge could increase or decrease (it allows you to set a negative increment).

[root@spissa:Active:Standalone] alertd # istats -help
Usage: istats <operation> [-s <segment-filename>] <key> [<value>]
   <operation> is one of: 'set' 'incr' 'get' 'remove' 'dump' 'drop_row'
           'drop_column' 'clear_row'
   <key> is a single quoted argument: "keyspace <table> <column> <value> ... <type> <measure>"
           (like "ltm.pool /Common/mypool counter mystat")
   <type> is one of: 'counter' 'gauge' 'string' 'text' 'signed' 'unsigned' 'bin'
           'dec' 'hex' 'timestamp' 'timeval' 'uinthex'
   <value> must be specified for 'set' and 'incr', and must be an integer for 'incr'
           The <value> for a gauge may be negative.  Use 2 dashes before the
           negative value (like 'incr "... gauge ..." -- -1')

Regards,

Dario.

Twpsyn_'s avatar
Twpsyn_
Icon for Nimbostratus rankNimbostratus
May 24, 2021

So conceptually you might use a counter to record say the total connections handled by an iRule (incrementing on client_accept) and a guage to record the current connections (incrementing on client_accept, decrementing on client_closed)?

  • Dario_Garrido's avatar
    Dario_Garrido
    Icon for MVP rankMVP
    May 24, 2021

    Yes, it's exactly as you said.

    ​An example of decrementing a gauge value is:

    istats incr "uri /api gauge curr_reqs" -- -3

    Regards,

    Dario.

  • AlexBCT's avatar
    AlexBCT
    Icon for Cumulonimbus rankCumulonimbus
    May 25, 2021

    Ah, makes sense now - I think my understanding that it was taking the average of a bunch of values seems to have been wrong.

     

    Thanks both!