Logging

Logging

[Gregory Bellier]

Hello.

Until now, whenever I needed to log something, I used my own function
to log. From now on, I face new problems and I would like to use
syslog to get rid of my logging functions and use the proper unix
ones. However, from what I've seen, syslog logs in messages, user,...
but I can't log in a specific file like "my_project.log" unless I hack
in /etc/syslog.cnf (I don't recall the exact path).

How do you do in your projects ? I tried the following package:
libsyslog-ocaml-dev on Debian.

Thanks in advance for any inputs.

Gregory.

Re: Logging

[Sylvain Le Gall]

On 21-12-2010, Gregory Bellier <gregory.bellier@gmail.com> wrote:
> Hello.
>
> Until now, whenever I needed to log something, I used my own function
> to log. From now on, I face new problems and I would like to use
> syslog to get rid of my logging functions and use the proper unix
> ones. However, from what I've seen, syslog logs in messages, user,...
> but I can't log in a specific file like "my_project.log" unless I hack
> in /etc/syslog.cnf (I don't recall the exact path).
>
> How do you do in your projects ? I tried the following package:
> libsyslog-ocaml-dev on Debian.
>
> Thanks in advance for any inputs.

There is also Lwt_log.
http://ocsigen.org/lwt/doc/api/Lwt_log.html

Regards,
Sylvain Le Gall

Re: [Caml-list] Re: Logging

[Gregory Bellier]

2010/12/21 Sylvain Le Gall <sylvain@le-gall.net>:
>
> There is also Lwt_log.
> http://ocsigen.org/lwt/doc/api/Lwt_log.html

To be more verbose, I have two processes with two different effective
uid and I would like them to be able to log in the very same file and
not in /var/log/user.log but /var/log/my_project.log. That's why it's
convenient to call a daemon like syslog which handles the permissions
itself.

It seems that Lwt_log provides functions to call the syslog daemon to
log (which the other module also does) or logs itself. In which case,
I'd have the permissions problem because the log file would have the
identity of the running process which created it. Please correct me if
I'm wrong about Lwt_log.

How does Apache proceed ? You can specify where to log in the config
file and set it to /var/log/apache.log and it works while the process
runs with www-data identity.

Re: [Caml-list] Re: Logging

[Török Edwin]

On 2010-12-21 13:16, Gregory Bellier wrote:
> 2010/12/21 Sylvain Le Gall <sylvain@le-gall.net>:
>>
>> There is also Lwt_log.
>> http://ocsigen.org/lwt/doc/api/Lwt_log.html
> 
> To be more verbose, I have two processes with two different effective
> uid

If both processes start out as root then you can open the logfile before
dropping privileges.

Best regards,
--Edwin

Re: [Caml-list] Re: Logging

[Gabriel Kerneis]

On Tue, Dec 21, 2010 at 01:21:44PM +0200, Török Edwin wrote:
> On 2010-12-21 13:16, Gregory Bellier wrote:
> > 2010/12/21 Sylvain Le Gall <sylvain@le-gall.net>:
> >>
> >> There is also Lwt_log.
> >> http://ocsigen.org/lwt/doc/api/Lwt_log.html
> > 
> > To be more verbose, I have two processes with two different effective
> > uid
> 
> If both processes start out as root then you can open the logfile before
> dropping privileges.

But you must take care of concurrent writes (which is the reason why a
daemon is still a good idea).

Best,
-- 
Gabriel

Re: [Caml-list] Re: Logging

[Michael Ekstrand]

On 12/21/2010 05:16 AM, Gregory Bellier wrote:
> 2010/12/21 Sylvain Le Gall <sylvain@le-gall.net>:
>> There is also Lwt_log.
>> http://ocsigen.org/lwt/doc/api/Lwt_log.html
> To be more verbose, I have two processes with two different effective
> uid and I would like them to be able to log in the very same file and
> not in /var/log/user.log but /var/log/my_project.log. That's why it's
> convenient to call a daemon like syslog which handles the permissions
> itself.
>
> It seems that Lwt_log provides functions to call the syslog daemon to
> log (which the other module also does) or logs itself. In which case,
> I'd have the permissions problem because the log file would have the
> identity of the running process which created it. Please correct me if
> I'm wrong about Lwt_log.
>
> How does Apache proceed ? You can specify where to log in the config
> file and set it to /var/log/apache.log and it works while the process
> runs with www-data identity.

Apache is probably handling the concurrent writes itself.

If you want to use syslog, you will need to use appropriate syslog ident
and facility and configure your syslog daemon to filter those log
messages to a separate file.  It won't do that automatically (and
doesn't let you log to arbitrary files).

Otherwise, I think you'd need to write your own log daemon.

- Michael

Logging

[Tiago Antão]

Hi!

Are there any best practices/libraries regarding logging in CAML? My
main use for it will be debugging (I know there are debugging
facilities in CAML, but I am very used to using log as a debug tool -
think Log4J for instance)...

Thanks a lot,
Tiago