Add support for BSD style syslog messages RFC 3164 to syslog input

[vit1251]

Relevant telegraf.conf:

=udp4://:6514

System info:

1.7.3

Steps to reproduce:

1. Setup UDP input syslog plugin
2. Setup nginx output in that UDP port

Expected behavior:

Message store in InfluxDB

Actual behavior:

Error in plugin [inputs.syslog]: read udp4 0.0.0.0:6514: i/o timeout

Additional info:

No idea.

[danielnelson]

Can you show your nginx config for sending over UDP?

[vit1251]

@danielnelson I setup nginx by manual at address http://nginx.org/en/docs/syslog.html

access_log syslog:server=127.0.0.1:6514,tag=nginx;

I watch tcpdump UDP and view that UDP packet push on lo interface.

[danielnelson]

I believe the issue is that nginx outputs only in RFC 3164, but the syslog input only does RFC 5424 messages. There is an issue on go-syslog to add support: influxdata/go-syslog#15.

In the meantime I think a workaround would be to use rsyslog to convert between formats.

[vit1251]

@danielnelson maybe an interesting fact or my mistake I'm not exactly sure but... after error ocuire I try to make custom message by logger from shell and no message pass in Influx. I guess that parsing goroutine ended and no more ready to receive UDP packet. Perhaps this is a mistake.

[danielnelson]

I set up rsyslog to forward over UDP:

$ cat /etc/rsyslog.d/50-telegraf.conf
$ActionQueueType LinkedList # use asynchronous processing
$ActionQueueFileName srvrfwd # set file name, also enables disk mode
$ActionResumeRetryCount -1 # infinite retries on insert failure
$ActionQueueSaveOnShutdown on # save in-memory data if rsyslog shuts down

*.* @127.0.0.1:6514;RSYSLOG_SyslogProtocol23Format

And then used the logger command from util-linux:

$ logger test

I did get the message, but also an error message:

2018-08-28T20:30:30Z E! Error in plugin [inputs.syslog]: read udp [::]:6514: i/o timeout
syslog,appname=dbn,facility=user,host=debian-stretch-syslog.virt,hostname=debian-stretch-syslog,severity=notice version=1i,severity_code=5i,facility_code=1i,timestamp=1535488225311326000i,message=" test" 1535488225311871493

Afterwards, I am unable to send to this socket. I think we just want to remove the deadline for the UDP socket altogether, I'll put together a pr.

[danielnelson]

@vit1251 You should be able to craft a message directly now if you use the nightly builds.

[NWMichl]

+1 for adding RFC 3164 style (UDP) syslog receiver to Telegraf.
(Not only) We have tons of network equipment in the field without the capability to send according to RFC5424 format.

[janitha]

go-syslog now supports RFC 3164 as per influxdata/go-syslog#27 (merged feb 3)