Re: [Perfparse-users] perfparsed & pipe

[Tim W. <tim...@gm...>]

Yves,

On Mon, 22 Nov 2004 11:07:42 +0100 (CET), Yves <yme...@pe...> wrote:
> 
> 
> 
> > Has anyone managed to use 'method 4' , i.e. make nagios write to a
> > pipe that is read by perfparsed?
> >
> > I managed to get it to work once, but then I killed perfparsed and
> > tried to restart it and it never comes up again. In the error log I
> > see this:
> > 2004/11/22 10:11:18 [log_reader.c:370   9800  ] Could not create fifo
> > '/usr/local/nagios/var/perfparse.pipe'
> >
> > The problem is that perfparse.pipe still exists from the previous run.
> > But you can't get rid of it, because nagios is constantly writing to
> > it. If you remove it, it instantly reappears as a regular file!
> 
> Yes, of course. In a perfect world, nagios (the nagios command that outputs to the pipe)
> should test if the file exists and if it is a pipe, or raise an error.
> In our world, what can we do ?

We can rewrite the command that writes to the pipe :)
I added a check to perfparse_nagios_pipe_command.pl that check if
$file is a pipe. I use nagios 1.x, so it's not a bug in nagios. (pfew
:) )

> 
> > OK, I could shutdown nagios and restart perfparsed first and then
> > nagios again, but this is not really an acceptable solution.
> 
> What version of nagios are you using ? Any version with some command that printf >>
> perfparse.pipe ? Or nagios-2.0cvs with the new feature : output perfdata to a pipe ?
> 
> In the second case, this would be a bug in nagios and should be addressed to nagios
> developers.
> In the first case...
> 1 update your command to get closer from the perfect world ? You can do it, but will
> others do it too ?
> 2 update perfparsed to take care of this ? But fixing somewhere a bug of somewhere else
> is never a good solution. We get away from the perfect world.
> 3 ask the user to reboot nagios at the same time as perfparsed restarts ? But is this a
> good solution ?
> 
> I have an idea for (2) : when perfparsed starts and finds the existing file
> perfparse.pipe, it can rename it and create the fifo. Then it's your work to cat
> perfparse.pipe.old > perfparse.pipe. And it supposes that nagios closes the file and
> reopens it every time there is something to write. Otherwise, the only way is to reboot
> nagios.
> 
> Is this a correct workaround ?

Perfparsed definitely needs a fix, because the code that creates the
fifo queue fails if the queue (or file) already exists, and perfparsed
always exits. So a better fix would be:
if file exists {
     if file is a pipe {
         do nothing
     } else {
          rename the file (remove?)
          mkfifo
     }
  } else {
     mkfifo
 }

Tim.


> 
> 
> > My perfparse.cfg:
> > nagios@naxos:~/etc$ cat perfparse.cfg
> 
> Please run perfparsed --show_config instead :)
> In next version, I will write at the beginning of the exemple config file to run the
> binary with --show_config instead of showing the config file.
> However, thanks for sending the config file that usually helps us to find good things :)
> 
> Yves
>