Generate a unique ID with the help of an iRule

[Dan44]

Hello everyone

I would like to generate a unique ID with the help of an iRule and place it in a header. The goal is to identify the HTTP request by the ID. Has anyone done something like this before?

What I have tried:

when HTTP_REQUEST priority 3 {


###Generate URL Tracing


for { set i 0 } {$i < 8 } { incr i } {
append rand_hex [format {%x} [expr {int(rand()*16)}]]
}
#log local0. "X-Request-ID: $rand_hex"




###Add X-Request-ID Header


if {not([HTTP::header exists X-Request-ID ])}{
	HTTP::header insert X-Request-ID $rand_hex


    }
}


when HTTP_RESPONSE priority 3 {
  HTTP::header insert X-Request-ID $rand_hex


}

The problem is that I sometimes see multiple requests with the same ID. Does anyone have a better idea how to solve it?

[Rob_Stonham]

Dan44,

I'm not sure about generating the unique ID, I'd look at this article https://devcentral.f5.com/s/articles/random-string-generators or keep it simple and generate an id like Kai Wilke suggested in https://devcentral.f5.com/s/question/0D51T00006i7W29/how-random-is-rand

set uniqueID [TMM::cmp_unit][clock clicks]

Your code also allows a client to supply the header X-Request-ID, is this intended behaviour?

Rob

[Dan44]

Hi Rob

Thanks for your reply, the links look interesting. I will have a look at them and test the examples.

Regarding your question. It is actually planned that only F5 LTM does the header insert and not the client.

[boneyard]

if that is the case you should remove the HTTP_RESPONSE part