Stats Profile funnies...

Question

Hi there, &nbsp;
&nbsp;I'm trying to implement an iRule for a dyncamic maintenance page using the following iRule: http://devcentral.f5.com/wiki/iRules.LTMMaintenanceWindow.ashx&nbsp;
&nbsp;However I'm having some weird issues with the stats profile... &nbsp;
&nbsp;It's almost like the stats profile is being stored differently for different sessions?!
&nbsp;Is this possible???&nbsp;
&nbsp;E.g. the following is a log extract from the above iRule... I've put in some additional logging to output the current values stored for the start and end times... &nbsp; Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/splunk_http : Sending log to Splunk...
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/splunk_http : Sending log to Splunk...
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/MaintenancePage : $day: 5, $start_time: 940, $end_time: 950
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/MaintenancePage : $start_time less than 4 characters
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/MaintenancePage : $start_time now 0940
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/MaintenancePage : $cur_day: 5, $cur_time: 1224
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/splunk_http : Sending log to Splunk...
&nbsp;Nov  4 12:24:15 tmm info tmm[6377]: Rule /Common/MaintenancePage : $day: 5, $start_time: 1220, $end_time: 1300
&nbsp;Nov  4 12:24:15 tmm info tmm[6377]: Rule /Common/MaintenancePage : $cur_day: 5, $cur_time: 1224
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/MaintenancePage : $day: 5, $start_time: 940, $end_time: 950
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/MaintenancePage : $start_time less than 4 characters
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/MaintenancePage : $start_time now 0940
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/MaintenancePage : $cur_day: 5, $cur_time: 1224
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/splunk_http : Sending log to Splunk...
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/MaintenancePage : $day: 5, $start_time: 940, $end_time: 950
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/MaintenancePage : $start_time less than 4 characters
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/MaintenancePage : $start_time now 0940
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/MaintenancePage : $cur_day: 5, $cur_time: 1224
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/MaintenancePage : $day: 5, $start_time: 940, $end_time: 950
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/MaintenancePage : $start_time less than 4 characters
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/MaintenancePage : $start_time now 0940
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/MaintenancePage : $cur_day: 5, $cur_time: 1224
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/splunk_http : Sending log to Splunk...
&nbsp;Nov  4 12:24:15 tmm2 info tmm2[6379]: Rule /Common/splunk_http : Sending log to Splunk...&nbsp;&nbsp;
&nbsp;As you can see from the above, some lines have a start_time and end_time of 940/950, and some have 1220/1300... 1220/1300 is the last value i've set... &nbsp;
&nbsp;Any ideas???&nbsp;
&nbsp;Cheers
&nbsp;Gavin &nbsp;

gavinw_29074 · Answer

Hmm, might be something or noting... But, i've had a closer look at the logs, and I can see that the different times being returned and being returned by different 'tmm' process'...  
&nbsp;  
&nbsp; tmm in the above log has the correct value, but tmm2 has the incorrect value...  
&nbsp;  
&nbsp; Is this a process sync issue?

spark_86682 · Answer

Each TMM only has read access to its own values for STATS profiles. Only processes outside of tmm (like tmsh, for instance) have access to combined stats across all TMMs. It is possible that that iRule was written when all or most systems only had one TMM. My suggestion is to use the session table (by using the table iRule command) in place of the STATS:: commands.

gavinw_29074 · Answer

Ok, looks like I'm rewriting the rule to use the session table then... &nbsp;
&nbsp;I'm thinking of re-working it slightly, so that instead of a day, start time and end time being passed in, only a start date-time and duration is required... &nbsp;
&nbsp;However I'm having some issues getting a string converted into a valid DT object... &nbsp;
&nbsp;"Clock scan" looks like the most appropriate, but it doesn't appear possible to specify a format option... &nbsp;
&nbsp;Any pointers?&nbsp;
&nbsp;Cheers
&nbsp;Gavin &nbsp;

gavinw_29074 · Answer

OK, looks like I've managed to get a workable solution in place...  
&nbsp;  
&nbsp; Below is the code that I've created. Thought I'd post it here for comment before submitting to Code Share.  
&nbsp;  
&nbsp; Cheers 
&nbsp; Gavin  
&nbsp;  
&nbsp; when RULE_INIT {

set static::SUBTABLE "maintenance_window"
  set static::debug 1

Global variable to use within other iRules to prevent multiple invocation errors. 
  set ::MAINTENANCE_MODE 0
  
}

when HTTP_REQUEST priority 10 {
  
  set VS_NAME [virtual name]
  set TITLE "[substr $VS_NAME 8] iRule Maintenance Window Control"
  set PROFILE [substr $VS_NAME 8]
  set PROFILE_NAME [concat [string map {. _} $PROFILE]_maintenance_window]
  
  if {$static::debug == 1} { log local0.info "VS Name: $VS_NAME Title: $TITLE Profile: $PROFILE Profile Name: $PROFILE_NAME" }

Look for embedded commands to control the maintenance window.

switch -glob [string tolower [HTTP::uri]] {
    "/enable*" {

Extract the maintenance window day, start date time, and duration from the URI. 
       If not there, return an error message.

set params [split [HTTP::uri] "/"]
      if { [llength $params] &lt; 4 } {
        HTTP::respond 200 content "
          $TITLE
          Usage: http://[HTTP::host]/enable/start_date_time/duration
  Start Date Time must be of the format yyyy-mm-dd hh24:mi:ss
  Duration is in Hours
  
          "
      } else {

Assign the values to variables.

set START_VALUE [string map {"%20" " "} [lindex $params 2] ]
set DURATION_HOURS [lindex $params 3]
if {$static::debug == 1} { log local0.info "Start Value = $START_VALUE, Duration = $DURATION_HOURS." }

Process input
        set START_EPOCH [clock scan $START_VALUE ]
if {$static::debug == 1} { log local0.info "Start EPOCH = $START_EPOCH" }

set DURATION_SECS [expr {$DURATION_HOURS*60*60}]
if {$static::debug == 1} { log local0.info "Duration = $DURATION_SECS" }

Add value to subtables
table set -subtable $static::SUBTABLE $PROFILE_NAME $START_EPOCH 0 $DURATION_SECS

HTTP::respond 200 content "
          $TITLE
          Maintenance Window enabled
          "
      }
    }
    "/disable" {

By removing the session table entries, the maintenance is removed.
  if {$static::debug == 1} { log local0.info "Removing set Maintenance window..." }
      table delete -subtable $static::SUBTABLE $PROFILE_NAME
  
      HTTP::respond 200 content "
        $TITLE
        Maintenance Window disabled
        "
    }
    "/check" {

Return the current time and the current settings for the maintenance window
set START_EPOCH [table lookup -subtable $static::SUBTABLE $PROFILE_NAME]
 Set Common variables. 
set NOW_EPOCH [clock seconds]
set NOW_DTS [clock format $NOW_EPOCH ]

if { $START_EPOCH != "" } {
set START_DTS [clock format $START_EPOCH]
set DURATION [table lifetime -subtable $static::SUBTABLE $PROFILE_NAME]
set DIFFERENCE [expr { $NOW_EPOCH - $START_EPOCH } ]
set RESPONSE "$START_DTS for [expr {$DURATION/60/60}] hours"

Debug Logging
if {$static::debug == 1} { 
log local0.info "Maintenance window set..."
log local0.info "Table values: Start EPOCH - $START_EPOCH Duration - $DURATION" 
log local0.info "Start DTS = $START_DTS Date Time now = $NOW_EPOCH" 
log local0.info "Difference = $DIFFERENCE"
}
} else {
set START_DTS "No Maintenance Window set"
set RESPONSE $START_DTS

Debug Logging
if {$static::debug == 1} { log local0.info "No Maintenance Window set..." }
}

HTTP::respond 200 content "
  $TITLE
  Current Date and time: $NOW_DTS
Maintenance Window: $RESPONSE
  "
    }
    "/usage" {

Usage instructions for the commands

HTTP::respond 200 content "
          $TITLE
          Usage: http://[HTTP::host]/$$command$$
          
            /enable/start_date_time(yyyy-mm-dd hh24:mm:ss)/duration(h) - enable maintenance window.
            /disable - disable maintenance window.
            /check - check if in maintenance window.
            /usage - display this usage message
          
          "
    }
    default {

no secret command entered, so check the maintenance window

Get the values from the statistics profile.
set START_EPOCH [table lookup -subtable $static::SUBTABLE $PROFILE_NAME]
set DURATION [table lifetime -subtable $static::SUBTABLE $PROFILE_NAME]

Debug logging 
if {$static::debug == 1} { log local0.info "Table values: Start EPOCH - $START_EPOCH Duration - $DURATION" }

Check if start_epoch is non-null. 
if { $START_EPOCH != "" } {

Use the TCL "clock" command to get the current time as epoch.
        set NOW_EPOCH [clock seconds]
        if {$static::debug == 1} { log local0.info "Current EPOCH Time = $NOW_EPOCH" }
        
 Check NOW against Scheduled start
if { $NOW_EPOCH &lt; $START_EPOCH } {
 Not yet in maintenance, therefore return for other processing
return

} else {
 Now must be greater than Start Epoch value, therefore in maintenance or after maintenance
set DIFFERENCE [expr { $NOW_EPOCH - $START_EPOCH } ]
if {$static::debug == 1} { log local0.info "Difference between Now and Start Epoch is $DIFFERENCE" }

if { $DIFFERENCE &lt; $DURATION } {
 Within maintenance window
if {$static::debug == 1} { log local0.info "In Maintenance window - Returning holding page." }
if { [HTTP::uri] ends_with "logo-act.png" } {
if {$static::debug == 1} { log local0.info "Returning Logo..." }
HTTP::respond 200 content [b64decode [class element -value 0 act_logo_png]] "Content-Type" "image/png"
} else {
if {$static::debug == 1} { log local0.info "Returning html..." }
HTTP::respond 200 content [class element -value 0 offline_page_html] "Content-Type" "text/html" 
}

Set Maintenance mode global variable. 
set ::MAINTENANCE_MODE 1

} elseif { $DIFFERENCE &gt; $DURATION } {
 Outside of Maintenance window
if {$static::debug == 1} { log local0.info "Outside of Maintenance window. Unsetting Maintenance Mode." }

Unset maintenance mode flag for good measure
set ::MAINTENANCE_MODE 0

Remove session table entry. 
table delete -subtable $static::SUBTABLE $PROFILE_NAME
}
}

} else {

Not in maintenance window, so allow connection to continue to application.
if {$static::debug == 1} { log local0.info "Not In Maintenance window - Continuing." }

Ensure Maintenance Mode global variable is unset. 
set ::MAINTENANCE_MODE 0

}
    }
  }
}

hoolio · Answer

I haven't read through the whole rule, but one simple optimization would be to use a subtable instead of a global variable for maintenance_mode.  A subtable will be CMP compatible whereas a global variable will pin the iRule to running only on the first TMM instance. 
&nbsp;  
&nbsp; See the CMP page for details: 
&nbsp; http://devcentral.f5.com/wiki/iRules.CMPCompatibility.ashx 
&nbsp;  
&nbsp; Aaron

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