Feature request: var_module - ability to choose variables scope

[rsawer]

Hi, I'm trying to solve the problem of knowing the ESI includes status in the parent request by using the global variables of the var module. What I'm doing exactly is if I found an error in ESI response, then I'm creating a global variable called "error_". Then in the parent request I'm checking the existance of the "error_" var.

I'm worried that during the varnish lifetime, the memory will be full of error_* variables. I cannot use var.set/var.get because they're in PRIV_TASK scope, and I've found that there's a PRIV_TOP scope, which is designed for requests spanning through the parent and it's subrequests. I've tried simply changing that scope in vmod_var.vcc and recompile the modules, but unfortunatelly varnish crashes after calling the function with changed scope.

Would it be possible for you to implement a different scope variables?

[daghf]

By the time Varnish processes the includes, the top-level VCL processing is already over, so you won't be able to communicate back up the chain from a sub-request to the top-level request.

Getting PRIV_TOP would let you communicate state from a top-level request down to its children. That could certainly be a useful feature. I can't make any promises that it is something we will have time to do anytime soon, but if you're willing to take a stab I can tell you contributions are welcome.

[rsawer]

Thanks for the feedback, I'll be waiting for further development

[nigoroll]

@rsawer you might want to have a look at https://code.uplex.de/uplex-varnish/varnish-objvar/blob/master/src/vmod_topvar.rst from https://code.uplex.de/uplex-varnish/varnish-objvar

[dridi]

Closing in favor of @nigoroll's solution. Please reopen if his module does not suit you.