Module development question - Variables

Server NGINX
1

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?

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

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.

Jan

2

Hello!

On Thu, Aug 15, 2013 at 03:40:59PM +0200, Jan A. 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.

  1. Whether I should / can call it myelf to set the variable.

Usually no.

E.g.:
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 D.
http://nginx.org/en/donation.html