Error log not reflect the problem related log

Server NGINX
1

Hi

I have configured the nagios on centos, I have perl related code that
I have set.

the problem is that when I was configured the same, it had a problem of
database connection, but in error log it shows the error like 502 bad
gateway or other error which not reflect the error related to database.
Means from the error I was not able to conclude that what was the
problem.

Is there any way to change the error log setting so it reflect the
exact problem ?

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2

Hello!

On Tue, Mar 20, 2012 at 05:49:17AM -0400, niraj wrote:

Is there any way to change the error log setting so it reflect the
exact problem ?

The exact reason is expected to be in your backend’s log. It’s
your backend which failed to produce response, nginx doesn’t known
why it failed to do so.

Maxim D.

3

Hi

 backend's log  mean in which file ?

 I was using apache (httpd) also in that access.log and error.log in

that if any application having any error then it reflect in error log.
at the same time that was not happened in Nginx.

can you tell me how can I diagnose my application related error ?

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4

Hello!

On Tue, Mar 20, 2012 at 07:01:53AM -0400, niraj wrote:

 backend's log  mean in which file ?

This depends on which backend do you use to execute your
application. E.g. if you use Apache as a backend - it will be
Apache’s error log.

Maxim D.

5

Hello!

On Tue, Mar 20, 2012 at 08:56:44AM -0400, niraj wrote:

Hi

Very True, If application use apache then logs in apache's error

log.

But now I am using Nginx, and its error log not give the details error
due to that from error log we are not able to rectified the issue.

You suggested backend’s log but I dont found any backend’s log which can
help to rectified the issue.

By itself nginx doesn’t execute applications. You haven’t
provided any information about which backend you’ve configured to
do so, therefore it’s unlikely that anybody will be able to help
you to find your backend’s logs.

Maxim D.

6

Hi

Very True, If application use apache then logs in apache's error

log.

But now I am using Nginx, and its error log not give the details error
due to that from error log we are not able to rectified the issue.

You suggested backend’s log but I dont found any backend’s log which can
help to rectified the issue.

Posted at Nginx Forum:

7

Hello!

On Wed, Mar 21, 2012 at 12:33:34AM -0400, niraj wrote:

Hi
I am using the application which having code in perl. I have both
html and cgi files.

For Cgi and perl files I have install the fcgi and spawn-fcgi and
configure the same in Nginx configuration.

What do you mean by “fcgi” here? Perl cgi files aren’t able to
talk via the FastCGI protocol, you either have to change them to
use the FastCGI protocol (e.g. by using FCGI perl module), or need
some wrapper which will do fastcgi to cgi protocol conversion.

(Note well that spawn-fcgi isn’t a fastcgi/cgi wrapper, it’s just a
simple helper program to start multiple processes of a fastcgi
application.)

In theory fastcgi allows to pass errors from an application to
server via special FCGI_STDERR stream (and nginx will log such
errors into it’s error log at ‘error’ level with “FastCGI sent in
stderr” prefix). Though in practice this requires fastcgi
application to properly redirect errors into the stream in
question, and this isn’t always done properly.

Maxim D.

8

Hi
I am using the application which having code in perl. I have both
html and cgi files.

For Cgi and perl files I have install the fcgi and spawn-fcgi and
configure the same in Nginx configuration.

For database I am using Mysql and OS is Cent OS.

Is any other information required ?

Please suggest where would be the exact error log for this application
which can help to solve the application related error.

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9

k Thnkx

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