irule static::debug

A few things to note:

1. It is global [1], so while it is common to see

   static::debug

   , it's not best-practice to do so. The reason is, if you use

   static::debug

   in more than one iRule, and set it to different values in each of the rules, the final value will apply to all iRules and will be essentially non-deterministic [2]. There are several ways to remedy this, but a common approach -- and the one I think is easiest -- is to simply choose a unique prefix for each iRule. So, if you have three rules that want to use

   static::debug

   , you might use

   static::abc_debug

   ,

   static::def_debug

   and

   static::ghi_debug

   (okay, use something more meaningful that

   abc_

   , etc.);

2. These

   if { $static::abc_debug } { ... }

   commands will be evaluated on each connection. So, while the use of the "debug" value is useful when building or changing an iRule, I strongly recommend commenting these out (or removing them) for production. For complex rules, some people create an iApp which essentially inserts debugging into a rule (or uncomments existing statements) so that debugging can be "turned on" and "turned off".

[1] To be completely pedantic, it is tied to a tmm, so if you were to change this or any

static::

scoped variable, the change would be visible only to other connections being processed on the tmm instance where the change was made. There is a valid and quite useful case for this, but 99% of the time -- and unless you really know what you're doing and why -- treat a

static::

variable as a constant and don't change it.

[2] It will be the value in the last iRule loaded which attempts to set this value, but that ordering could change over time.