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Homesh
@Homeshjoshi_twitter
I am working on another workaround. Idea is since only the syslog-ng will access the files, I am using inotifywait -m -r -e close_write --format '%w%f' "${MONITORDIR}" | while read NEWFILE
do
rm ${NEWFILE}
done
This way once the file is read by syslog-ng it is getting deleted. here i am assuming that the file is process by syslog-ng ( which is the case for most of the time) I see all the files reaching my elasticsearch. Howerver I see below entries in log 2021-06-08T11:32:14.259750] Follow-mode file source not found, deferring open; filename='/var/log/apache2/93200/20210608/20210608-1702/20210608-170214-YL9VPvA4UO9fAg2IkuODWQAAAAI' is there any issue due to this ? i expect this will remove the file from monitoring ( hence keep the number of files well under the max-file count)
Second I see empty directories (due to above mentioned script) e.g /var/log/apache2/93200/20210608/20210608-1702 will this cause issue for syslog-ng ( as it will still monitor these directories for possible new file, I think I should also delete the empty directories immediately. Please suggest
Homesh
@Homeshjoshi_twitter
Hi @alltilla can you please suggest.
László Várady
@MrAnno

Hi @Homeshjoshi_twitter,

If I understand it correctly, the inotifywait -m -r -e close_writescript of yours will remove the file right after a process writing that file closes its fd.

Fortunately, when syslog-ng opens a file for reading, it keeps that file open. This means that if the file is deleted before it is fully processed by syslog-ng, we can still finish reading the file (The file will not really be deleted until the last FD is closed).

The only problematic scenario is when a file is deleted, but syslog-ng has not yet been able to open the file in that amount of time.
I think this is the case when you get the message you mentioned: Follow-mode file source not found

László Várady
@MrAnno
The wildcard-file() source monitors files continuously, we don't close those files after processing them, so I think you either have to add a few-second delay before removing the file (in the hope syslog-ng can open it), or you should choose a different approach (a simple delay does not guarantee anything, but monitoring syslog-ng statistics (syslog-ng-ctl stats), or searching for internal debug logs that state we opened the file might actually work)
Homesh
@Homeshjoshi_twitter
Hi @MrAnno , thanks for the reply. My logic is once the file is read by syslog-ng it should get deleted, since no new log is going to be written by application in that file (due to concurrent logging). What I finally understand from your reply that my script is not going to work. I can not keep debug ON for production to check for files process by syslog-ng. My only option left is to use elasticsearch's filebeat as it can delete the file once it is process like logstash ( filebeat is lighter than that of logstash) and then filebeat will write the logs to a new single file or it can forward to syslog-ng on syslog port (e.g 514), I do not wanted to add dependency on filebeat or any other program, but now I don't have option until syslog-ng will offer the same feature of filebeat or logstash. Logstash hangs after 7 to 8 days and consumes lot of memory and cpu. That is why I want to replac logstash with syslog-ng. Thanks again for your reply.
László Várady
@MrAnno

@Homeshjoshi_twitter

What I finally understand from your reply that my script is not going to work.

Adding a few-second delay might work, but it's an ugly hack, and nothing is guaranteed.

The better option (until we implement #3695) would be something that relies on the statistics of syslog-ng.
For example, it is possible to write a script that periodically checks the output of the sbin/syslog-ng-ctl query get 'src.file.*.processed' command, and removes the file only when the processed counter of the file can be found in the list, and it is greater than 0.

This should work reliably only if you do NOT re-create the same file (path) after deleting it (syslog-ng file statistics are not reset after the file is removed).

Homesh
@Homeshjoshi_twitter
Interesting !! let me try this and share my experience. Thanks a lot @MrAnno
László Várady
@MrAnno
My pleasure
arekm
@arekm:matrix.org
[m]
Hi, using log { source(s_sys); destination(log_net); }; to log all logs into remote syslog. But that makes "log { source(s_sys); destination(d_messages); flags(fallback); };" not logging things locally due to fallback flag. Is there a way to mark my log_net logging somehow, so it doesn't interfere with fallback logging?
László Várady
@MrAnno

@arekm:matrix.org Hi,
The fallback flag is for processing messages that are not processed by any other normal log paths. You can not mark log_net as an "invisible" destination, but I'm pretty sure we can refactor/rephrase your configuration to achieve what you want; for example, using if-else blocks, or embedded log paths, final flags, or just filters.

Can you share all of your log paths, where s_sys is used? Exactly what messages would you like to see arrive into d_messages?

arekm
@arekm:matrix.org
[m]
The goal here is to use default syslog-ng config and only put one file in syslog.d/ that will push all logs to remote server, too. if/else/final won't play well with such assumption
(one file in... == one additional configuration file)
László Várady
@MrAnno
Oh I see. Is this your own custom default config? (I checked our default configurations (DEB, RPM, Arch Linux packaging) and could not find this fallback path.)
arekm
@arekm:matrix.org
[m]
PLD distro config.. which I could change in pld itself, too actually. I'll see how syslog-ng upstream config looks like
mshah618
@mshah618
Hi All,
I'm new Here and want to explain an issue I'm facing with syslog-ng.
I'm communicating to a server through a client. The client is on syslog-ng-v3.16.1 and the server is on syslog-ng-v3.10.1
Now I'm seeing incorrect count values for suppressions messages on remote logs.
Please note that client is configured with suppress(600) and server is configured with suppress(0)
any suggestion is appreciable.
Balázs Barkó
@Barkodcz

Hi @mshah618 ,
what do you mean it's incorrect count values for suppression messages?
just to be clear, when you say remote logs you mean the server logs?

For my opinion, it is possible if you update syslog-ng on your server it will solve the problem.

mshah618
@mshah618
Thanks, @Barkodcz for responding.
remote logs = server logs
when a message is for client, it starts suppression and looks for repeated messages.
once this repeated message steak is over, it logs "<MSG> repeated N times" and that log is also stored in server.
Now the problem I'm facing is the "repeated N times" value of N is sometimes different in server logs.
Hope I explain the issue well.
So Is there any open issue present currently? Do you know if this type of issue occurred before and fixed in later releases?
Balázs Barkó
@Barkodcz
Hi @mshah618 , can you send me your config please?
It could help for debugging and understanding the problem.
mshah618
@mshah618
Hi @Barkodcz , Can you share me your email id? I'll share those configs to you.
László Várady
@MrAnno

Hi @mshah618,

Now the problem I'm facing is the "repeated N times" value of N is sometimes different in server logs.

Could you elaborate on this a bit more? Did you find some inconsistencies between the client and server logs when using the suppress option?
Or do you expect a fixed amount of repetition within 600 seconds?

When a client is configured with the suppress(T) option, consecutive repetitive messages will be sent only once within that T timeframe. Please note that any non-identical message between 2 identical messages will reset the suppress counter.
After T seconds or when a non-identical message is found, the following summary will be sent to the server:
Last message 'msg' repeated N times, suppressed by syslog-ng on ...

Can you share me your email id? I'll share those configs to you.

Could you share the relevant parts of your configuration publicly? More people can help you that way. :) You can remove sensitive information from the config.
If that's not possible, you can, of course, send your config to any of us in a private message.

mshah618
@mshah618

Hi @mshah618,

Now the problem I'm facing is the "repeated N times" value of N is sometimes different in server logs.

Could you elaborate on this a bit more? Did you find some inconsistencies between the client and server logs when using the suppress option?
Or do you expect a fixed amount of repetition within 600 seconds?

I see inconsistencies between client and server logs when using suppress option.

László Várady
@MrAnno
What exactly do you see? When suppressing logs on the client side, the server receives the summary message itself (Last message 'msg' repeated N times), so messages are not recounted on the server side, you will have to see the exact same message there.
mshah618
@mshah618
yes but I see different counts sometimes
not only on server side, but sometimes I see wrong count number on client side and correct count on server side

Some times server log contains wrong number of repeated messages, some times client log contains it.

Some times client and server logs show correct, equal value.

László Várady
@MrAnno
How do you validate which side has the "correct count"?
Do you have 2 different destinations (a local file and a network?) configured with the suppress() option on the client side?
mshah618
@mshah618
Yes
László Várady
@MrAnno
Every destination has its own suppress timer and counter, so the two will not always produce the same output.
For example, if one of the 2 destinations receives messages from other sources as well, the suppress output will be completely different.
László Várady
@MrAnno

Yeah, that might be the consequence of 2 destinations receiving messages from slightly different sources or log paths.
Could you share your client and server configs, please? You can send it as a private message here on Gitter, if you want to.

I'll summarize what we've found here, publicly.

mshah618
@mshah618
Sure
László Várady
@MrAnno
A brief summary: we could not figure out how the client forwards messages to the server because the configuration does not contain any network destinations, only files.
I think some infrastructural details should be shared before moving forward with this problem. TLDR: suppress() is done on the client-side (by destinations), each destination has its own suppress counter/timer, so inconsistencies between the server and client side seems to be a configuration issue (for example, 2 different destinations are used on slightly different log paths, etc).
PLANTROON
@plantroon
I have some information in PROGRAM macro, which I would like to use in the destination's path on the filesystem. However, I want to use only part of PROGRAM in the path, how do I go about this?
PLANTROON
@plantroon

ok I figured it out. If I have it like this:

log {
    source(s_myservers_tls);
    filter{program(apache_error)};
    parser(p_apache_error);
    rewrite(r_rewrite_subst);
    destination(df_new_apache_error);
};

will the rewrite be applied AFTER the previous filter() directive? (so will the filter() be respected? Because with rewrite being done, the filter's input data would change and not work for this given filter)

PLANTROON
@plantroon
what happens is that apache_error_domain.tld changes to domain_tld with that rewrite
László Szemere
@szemere

Hello @plantroon ,

the statements in the Syslog-ng configuration file are "executed" from top down. So the filter will be applied to the original PROGRAM field. And the later rewrite will only affect the following destination statement.

However I am not sure about your "p_apache_error" parser. If your parser also process/alters the PROGRAM field, you might want to put it prior your filter statement.

PLANTROON
@plantroon

Thanks :)

However I am not sure about your "p_apache_error" parser. If your parser also process/alters the PROGRAM field, you might want to put it prior your filter statement.

if I understand correctly, only the message itself is available to the parser, no? Therefore it does not work with the program field... at least mine does not. I use ewmm syslog driver if that has anything to do with it.

László Szemere
@szemere

First things first, I think your setup will work as is.

A little bit of explanation, why your parser only receives the message part:
Every parser has a "template" option, with a default $MESSAGE value. The template option defines the input of the parser. Since evmm already parsed the incoming message as a apache log, your PROGRAM field, and other apache related macros are already filled.

(Usually if somebody writes a custom parser, they use "flags(no-parse) on the source side, which combined with the default MESSAGE value for the template, will result getting EVERYTHING)

PLANTROON
@plantroon
ah I see :) thanks for explaining. It appears to work fine, it's been like this since 23:00 yesterday and logs are parsed and saved correctly
engineer11111
@engineer11111

hey there !

i'm trying to send logs from syslog-ng to elasticsearch(basically using syslog-ng as a proxy) and while this config perfectly works on my ubuntu 20.04 when i try to launch it inside docker it doesn't send anything

syslog-ng.conf

@version: 3.31
@include "scl.conf"

source s_network {
  network(
    port(514)
    transport("tcp")
  );
};

destination d_es{
  elasticsearch-http(
    index("syslog-ng")
    url("https://")
    user("admin")
    password("password")
    type("")
    tls( peer-verify(no) )
  );
};
log {
  source(s_network);
  destination(d_es);
};

things i've tried already :

  • launching container with --privileged flag
  • enabling verbose via syslog-ng-ctl mode - barely any new messages

i'm using docker image 3.31.2-buster aka latest

could anyone please help me with that one ?

László Szemere
@szemere

Hello! Naive question: are you sure that your container/syslog-ng indeed receives any log messages? (Exposing the 514 port, or using host network)

I am thinking about the Syslog-ng debug messages with the beginning of the "Incoming log entry" text.
i.e.: [2021-07-21T16:41:59.091937] Incoming log entry; line='<165>1 2003-10-11T22:14:15.003Z 1.2.3.4 evntslog - ID47 [example123456789

engineer11111
@engineer11111

hi!
thank you for getting back to me

it does receive log entries, i've tried both with simple network requests and setting it up to collect logs from syslog + making logs entries via logger

do i enable verbose mode the right way?

root@6b6a564571aa:/# syslog-ng-ctl verbose --set=on
VERBOSE=1
engineer11111
@engineer11111

ah, turned out verbose != debug
after enabling debug mode i've got a bunch of messages like this one

curl: HTTP response received; url='https://1234.eu-central-1.es.amazonaws.com/_bulk', status_code='200', body_size='276', batch_size='1', redirected='0', total_time='0.075', worker_index='1', driver='d_es#0', location='#buffer:4:3'

index still isn't there unfortunately

László Szemere
@szemere
May I recommend turning on trace messages too? (./syslog-ng-ctl trace --set=on) - Warning: it will print out a LOT of information.
With trace enabled cURL print out the response body too in the debug logs. Maybe the response will tell us more about the problem.
engineer11111
@engineer11111

i did it yesterday actually and indeed it produces a lot of messages
some of them like these

Jul 22 18:49:38 f62b8106c0bd syslog-ng[1]: cURL debug; worker='2', type='data_out', data=''
Jul 22 18:49:38 f62b8106c0bd syslog-ng[1]: cURL debug; worker='2', type='data_out', data=''
Jul 22 18:49:38 f62b8106c0bd syslog-ng[1]: cURL debug; worker='2', type='data_out', data=''
Jul 22 18:49:38 f62b8106c0bd syslog-ng[1]: cURL debug; worker='2', type='data_out', data=''
Jul 22 18:49:38 f62b8106c0bd syslog-ng[1]: cURL debug; worker='2', type='data_out', data=''

what logs specifically should i look for since it's really a lot of them ?

László Szemere
@szemere

Sorry, I did not take time to bring up an elastic instance. So I hit a local python wevserver with a simple http destination. I got the following output:

2021-07-23T07:33:42.837203] cURL debug; worker='0', type='data_in', data='<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN".        "http://www.w3.org/TR/html4/strict.dtd">.<html>.    <head>.        <meta http-
equiv="Content-Type" content="text/html;charset=utf-8">.        <title>Error response</title>.    </head>.    <body>.        <h1>Error response</h1>.        <p>Error code: 501</p>.        <p>Message: Unsupported
 method (\'POST\').</p>.        <p>Error code explanation: HTTPStatus.NOT_IMPLEMENTED - Server does not support this operation.</p>.    </body>.</html>.'

But there should be something similar in your output too.