Linux – Writing to Unix Domain Socket from rsyslog

linuxrsyslogsocketunix

I want to write output messages from rsyslog to a Unix Domain Socket. I want to do this so that I can read the messages from that socket using my script and parse log messages further.

I try to use omuxsock but it was not creating any socket.

Is this possible and if, how I configure rsyslog correctly to write to a socket?

Edit:

This is what i edited in /etc/rsyslog.conf 

$ModLoad omuxsock
$OMUxSockSocket /tmp/sock
*.* :omuxsock:

Best Answer

Yes, it is possible, and the given config is already correct*, as per rsyslog docs: http://www.rsyslog.com/doc/v8-stable/configuration/modules/omuxsock.html.

There is a mistaken assumption, however, in the statement "omuxsock ... was not creating any socket." omuxsock is not expected to create the socket; it expects to transmit to an existing socket. This is likely why @HBruijn suggested including the configuration "used to try setting up the socket".

Here is an example of such a setup in Python:

import socket
sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
sock.bind('/tmp/sock')
print(sock.recv(4096))

This works with the configuration given in the question, and will block until it receives a message over the socket.

Note that omuxsock only supports SOCK_DGRAM, not SOCK_STREAM (which would have been Python's default in the example above), and thus is connection-less (think UDP not TCP).

*Assuming of course that some input mechanism has also been defined and that it's desirable for everything (not previously excluded) to be logged to the given socket.

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