unable to capture complete http response in lua

gauravphoenix · 2014-11-17T09:18:10+00:00

Hello! On Fri, Nov 14, 2014 at 11:04 PM, Puneet Agarwal wrote: > I am using nginx and httpluamodule to serve http requests. > For some new requirement...

unable to capture complete http response in lua

gauravphoenix

My lua script looks like this- http://pastebin.com/hWSM2p6K

As you can see, I am trying to capture the complete HTTP pepose only if it is in the response to a POST request. When I review my log file, I am observing that only first ~8k bytes are getting logged. I got the code for body_filtter from this thread.

I understand that reading the whole response isn't very efficient process but that is okay in my use case- I need to capture response for very specific requests which constitutes less than 1% of all requests.

What am I doing wrong?

agentzh

Hello!

On Sun, Nov 16, 2014 at 5:18 PM, Gaurav Kumar wrote:
> As you can see, I am trying to capture the complete HTTP pepose only if it
> is in the response to a POST request. When I review my log file, I am
> observing that only first ~8k bytes are getting logged.

Are you aware of the hard-coded error log message length limit in the
nginx core? The official nginx core has the limit 2048 (bytes) while
OpenResty's bundled version of nginx has the limit 4096.

Error log messages longer than the limit will be truncated. Maybe
that's what you're seeing here? Better log the string length instead
of the string contents.

Regards,
-agentzh

gauravphoenix

Thanks you!

I wasn't aware of hard coded length restriction. After putting string.length in lua script, I think I am getting expected length. Thank you so much! I am now stuck at some other issue for which I will start a new thread.

On Mon, Nov 17, 2014 at 11:39 AM, Yichun Zhang (agentzh) <age...@gmail.com> wrote:

Hello!

On Sun, Nov 16, 2014 at 5:18 PM, Gaurav Kumar wrote:
> As you can see, I am trying to capture the complete HTTP pepose only if it
> is in the response to a POST request. When I review my log file, I am
> observing that only first ~8k bytes are getting logged.

Are you aware of the hard-coded error log message length limit in the
nginx core? The official nginx core has the limit 2048 (bytes) while
OpenResty's bundled version of nginx has the limit 4096.

Error log messages longer than the limit will be truncated. Maybe
that's what you're seeing here? Better log the string length instead
of the string contents.

Regards,
-agentzh

.