Buffers Chain

[Paulo Silva]

Because I don't have deep knowledge of nginx internal and I can not
find a proper resource about it, the best I can do and with what I am
comfortable is with body_filter.

Do you think I can notice whether all other 3rd party module filters
finish modifying the ngx_chain_t *in ?



On Fri, May 23, 2014 at 2:41 PM, Maxim Dounin <mdounin at mdounin.ru> wrote:
> Hello!
>
> On Fri, May 23, 2014 at 02:17:27PM +0100, Paulo Silva wrote:
>
>> Hi,
>>
>> On Fri, May 23, 2014 at 12:58 PM, Maxim Dounin <mdounin at mdounin.ru> wrote:
>> > Hello!
>> >
>> > On Fri, May 23, 2014 at 11:57:20AM +0100, Paulo Silva wrote:
>> >
>> >> there is other option than modify the auto/modules file?
>> >>
>> >> According to my goal (capture the full request response body) I would
>> >> say that my module must run right before the postpone.
>> >
>> > Before the postpone filter you'll get subrequest bodies in your
>> > filter, which is probably not what you want (the postpone filter
>> > is to glue subrequest together, correctly ordered).
>> >
>> >> Am I supposed to modify the auto/modules like follows?
>> >>
>> >> if [ $HTTP_POSTPONE = YES ]; then
>> >>     HTTP_FILTER_MODULES="$HTTP_FILTER_MODULES $HTTP_POSTPONE_FILTER_MODULE"
>> >>     HTTP_SRCS="$HTTP_SRCS $HTTP_POSTPONE_FILTER_SRCS"
>> >> fi
>> >>
>> >> # insert my module here!
>> >>
>> >> if [ $HTTP_SSI = YES ]; then
>> >>     have=NGX_HTTP_SSI . auto/have
>> >>     HTTP_FILTER_MODULES="$HTTP_FILTER_MODULES $HTTP_SSI_FILTER_MODULE"
>> >>     HTTP_DEPS="$HTTP_DEPS $HTTP_SSI_DEPS"
>> >>     HTTP_SRCS="$HTTP_SRCS $HTTP_SSI_SRCS"
>> >> fi
>> >>
>> >>
>> >> I did check my modules config file and I did realize that it is
>> >> "queued" as HTTP_AUX_FILTER_MODULES. There are different queues for
>> >> core modules and addons?
>> >
>> > The HTTP_AUX_FILTER_MODULES is a generic queue, and it's the
>> > only one currently officially supported for 3rd party modules.
>> >
>> > If you want your filter to be called right before/after postpone
>> > filter, it should be relatively safe to put it into the
>> > HTTP_POSTPONE_FILTER_MODULE variable though (and may be with some
>> > additional checks to make sure the postpone filter is enabled, or
>> > just a code to enable it unconditionally).
>> >
>>
>> And this is also valid when compiling nginx with the --add-module flag?
>> How does config file look like?
>>
>> My knowledge is restricted to Emiller's Guide To Nginx Module
>> Development (http://www.evanmiller.org/nginx-modules-guide.html) and a
>> few debugging hours.
>
> Uhm, looking again into auto/modules I think I was wrong, and
> modifying the HTTP_POSTPONE_FILTER_MODULE variable won't work
> (added module config scripts are executed later on), you should
> modify HTTP_FILTER_MODULES variable instead, and put your module
> into a proper position.
>
> Note that the "config" file of a module is just a shell script,
> and you are free to do more or less anything there.
>
> --
> Maxim Dounin
> http://nginx.org/
>
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> nginx-devel at nginx.org
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-- 
Paulo A. Silva
http://tech.pauloasilva.com
http://linkedin.com/in/devpauloasilva/