Hello!

On Thu, Aug 15, 2013 at 03:40:59PM +0200, Jan Algermissen wrote:

> Hi,
>
> been trying to understand variables for a couple of hours - but I jut don't get it.
>
> Can anyone explain,
>
>
> 1) How and when the variable setter function is called?

Something like this in a configuration:

set $variable "foo";

will result in v->set_handler() being called during the "set"
directive evaluation.

> 2) Whether I should / can call it myelf to set the variable.

Usually no.

> Use Case:
>
> I write an access phase filter that extracts a bunch of
> information from the Authorization header (think OAuth-like:
> clientId, user, but maybe also debug info about cryptography
> performance, token expiry, acess ricghts -you get the idea).
>
> I would like to store these per request values in a variable to
> use them in the access log module to log them.
>
> E.g.:
>
> log_format gzip '$remote_addr - $remote_user $my_module_client,
> $my_module_infoxy ...'
>
> I think I understand what I have to do to create the variable
> (create in preconfiguartin handler, provide setter function)
>
> But how is the setter called and how do I access the value to
> store in the variable?
>
> Should I make the value a static bucket in the module data that
> is written per request and then copied to the variable in the
> variable setter???
>
> Existing modules only help a little, as they mostly set
> variables to values that are part of the request struct anyway -
> which my values aren't.

In most cases, it's enough to store data in a module context and
provide a get_handler for a variable to access data via the module
context.

--
Maxim Dounin
http://nginx.org/en/donation.html

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