[syslog-ng] disk-buffer in elasticsearch2 destination loses messages if docker container is killed

Budai, László laszlo.budai at oneidentity.com
Wed Sep 19 11:46:51 UTC 2018 

Hi,

what do you mean under 'syslog-relay returns ACK to syslog-ng agent' ?
I guess this is TCP level ACK.

And TCP level ACK is not the same as what syslog-ng uses for controlling
the window size of the LogSources.

It is possible that you have pending data in TCP buffers (maintained by the
kernel) that is not read by syslog-ng, but they are already ACKd by TCP
itself...

(Solving this kind of situation requires application level ACK, which
syslog-ng has only in the commercial edition.)

L.

On Wed, Sep 19, 2018 at 9:23 AM, Jose Angel Santiago <jasantiago at stratio.com
> wrote:

> Hi,
>
> I've realized that the queue_length of the disk_buffer never goes beyond
> 99, no matter the ratio message/sec logger process is writing or the value
> of mem-buf-size or disk-buf-size.
>
> Which parameter is the one which would match the queue_length of the
> disk_buffer? It seems that it should be *mem-buf-length()* but I'm using
> reliable=yes so I shouldn't use that parameter, and I'd like to test my
> scenary being able to queue more than 99 messages on disk_buffer.
>
> Regards.
>
> 2018-09-17 14:33 GMT+02:00 Jose Angel Santiago <jasantiago at stratio.com>:
>
>> 3.17.2
>>
>> Thanks in advance.
>>
>> 2018-09-17 14:31 GMT+02:00 Budai, László <laszlo.budai at oneidentity.com>:
>>
>>> Hi,
>>>
>>> I'll try to reproduce this issue in my test environment.
>>> What syslog-ng version do you have?
>>>
>>> L.
>>>
>>> On Mon, Sep 17, 2018 at 2:04 PM, Jose Angel Santiago <
>>> jasantiago at stratio.com> wrote:
>>>
>>>> Hi,
>>>>
>>>> After repeating the test without TLS between syslog-agent &
>>>> syslog-relay, with 2229 messages logged with a 20 msgs/sec logging ratio,
>>>> in debug mode and with two tcpdumps running, these are the conclussions:
>>>>
>>>> - Syslog-agent sends every single message (checked with tcpdump file
>>>> and syslog-agent log file)
>>>> - Syslog-relay returns ACK for every single message, but sometimes the
>>>> package contains more than one message (checked with tcpdump file)
>>>> - Checking the syslog-relay log after killing & starting the docker
>>>> container, I found the trace 'Reliable disk-buffer state loaded;
>>>> filename='/syslog-ng-00000.rqf', queue_length='99', size='173844' and
>>>> the queued messages (from msg 236 to msg 334 are processed). The next
>>>> message processed is the nº 440. and it comes from the active network
>>>> destination again.
>>>> - Once all logs have been processed, in elasticsearch (syslog-relay
>>>> destination) I can find messages from 1 to 334, and messages from 440 to
>>>> 2229.
>>>>
>>>> How is it possible that syslog-relay returns ACK for messages 335 to
>>>> 439 to syslog-agent, but they are not in the queue, nor in the .rqf file?
>>>> Where did these messages go? I know they are sent before starting to fill
>>>> syslog-agent disk-buffer file (checked with rqf file from syslog-agent when
>>>> I kill the syslog-relay container). It seems that there's some kind of race
>>>> condition that makes those messages are not processed/queued  while
>>>> syslog-relay is being killed.
>>>>
>>>> Mi procedure consists of:
>>>>
>>>> . Start tcpdump on both syslog-agent & syslog-relay hosts
>>>> - Start logger process
>>>> - Once logs are being inserted in elasticsearch, I kill the
>>>> syslog-relay docker container, wait about 10 seconds, and run a new
>>>> container (using a mapped volume where .rqf file and .persist file are)
>>>> - Once logs are being inserted in elasticsearch again, I stop the
>>>> logger process.
>>>> - I wait until no log is left to be processed
>>>>
>>>> Would you test anything else? I'm running out of ideas.
>>>>
>>>> PD: Same test with logger process writing 5 msgs/sec ratio produces
>>>> from 0 to 5 lost messages.
>>>>
>>>> Regards.
>>>>
>>>>
>>>>
>>>>
>>>> 2018-09-14 14:05 GMT+02:00 Jose Angel Santiago <jasantiago at stratio.com>
>>>> :
>>>>
>>>>> Hi,
>>>>>
>>>>> I've got more accurate information about where are my lost messages.
>>>>>
>>>>> Now I'm using disk-buffer in syslog-agent and syslog-relay, and I've
>>>>> checked that lost messages are the ones sent by the syslog-agent when the
>>>>> syslog-relay docker container is being killed. I can see those messages on
>>>>> syslog-agent log (I've got both agent & relay in debug mode) with its
>>>>> corresponding "Outgoing message" line, but those messages never reach the
>>>>> relay.
>>>>>
>>>>> Could it be that the relay docker container still returns ACK to the
>>>>> agent (the agent resolves relay fqdn with a custom DNS) while syslog-ng
>>>>> process within the container is being stopped? I'm about to test again
>>>>> using tcpdump to confirm this theory,
>>>>>
>>>>> BTW, disk-buffers works ok, sometimes I get some duplicated messages
>>>>> when restarting the relay but that's not a problem for me. Forget about my
>>>>> .persist file re-creation theory, it doesn't happen.
>>>>>
>>>>> Regards.
>>>>>
>>>>>
>>>>>
>>>>> 2018-09-13 18:07 GMT+02:00 Péter, Kókai <peter.kokai at oneidentity.com>:
>>>>>
>>>>>> Hello,
>>>>>>
>>>>>> It would not make sense to replace the persist file after restart, so
>>>>>> it is not something that syslog-ng does. Only if that file is corrupted, in
>>>>>> that case at startup there should be a log about it, have you checked the
>>>>>> syslog-ng logs ? (it would be better to enable debug and/or verbose logs,
>>>>>> and if possible share it with us.)
>>>>>>
>>>>>> Could you reproduce the same behavior without docker (if possible) ?
>>>>>>
>>>>>>
>>>>>>
>>>>>> Best Regards,
>>>>>> Peter Kokai
>>>>>>
>>>>>> On Thu, Sep 13, 2018 at 4:44 PM Jose Angel Santiago <
>>>>>> jasantiago at stratio.com> wrote:
>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>> I guess I know what is happening, when I start from scratch the
>>>>>>> docker container, even I provide a persist file and a buffer file within
>>>>>>> the mapped volume, syslog-ng recreates them so all messages in buffer file
>>>>>>> which were not processed by the relay are lost.
>>>>>>>
>>>>>>> Is there any way to tell syslog-ng to use an already existing
>>>>>>> .persist file so it doesn't recreate the .rqf file?
>>>>>>>
>>>>>>> Regards.
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> 2018-09-13 16:23 GMT+02:00 Budai, László <
>>>>>>> laszlo.budai at oneidentity.com>:
>>>>>>>
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> one problem could be if the flush-limit would be greater than 1...
>>>>>>>> in that case syslog-ng would use a HttpBulkMessageProcessor.
>>>>>>>> In this case syslog-ng pass the message to the
>>>>>>>> HttpBulkMessageProcessor and sends back a positive ACK to the LogSource (so
>>>>>>>> the message is removed from the diskbuffer), and if the dockerimage is
>>>>>>>> killed, all the messages stored in the HttpBulkMessageProcessor are lost.
>>>>>>>> But in your case syslog-ng should use the
>>>>>>>> HttpSingleMessageProcessor... which means that the messages are sent
>>>>>>>> one-by-one...
>>>>>>>> Could you check the diskbuffer with the dqtool?
>>>>>>>>
>>>>>>>>
>>>>>>>> L.
>>>>>>>>
>>>>>>>> On Thu, Sep 13, 2018 at 3:50 PM, Jose Angel Santiago <
>>>>>>>> jasantiago at stratio.com> wrote:
>>>>>>>>
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> I'm running syslog-ng (with an elasticsearch2 destination
>>>>>>>>> configured) within a docker container, and I'm trying to avoid loss of
>>>>>>>>> messages if I kill the docker container and I start it again.
>>>>>>>>>
>>>>>>>>> This is my scenary:
>>>>>>>>>
>>>>>>>>> - A service which produces 20 lines of log per second
>>>>>>>>> - A sislog-ng instance reading from a wildcard-file source (but
>>>>>>>>> actually it only reads logs from the above service, let's call it
>>>>>>>>> syslog-agent), which sends all logs to another syslog-ng instance (the one
>>>>>>>>> running in a docker container, let's call it syslog-relay) though a network
>>>>>>>>> destination.
>>>>>>>>> - The syslog-relay sends messages to an elasticsearch instance,
>>>>>>>>> with following configuration:
>>>>>>>>>
>>>>>>>>> options {
>>>>>>>>>     chain-hostnames(no);
>>>>>>>>>     use-dns(no);
>>>>>>>>>     keep-hostname(yes);
>>>>>>>>>     owner("syslog-ng");
>>>>>>>>>     group("stratio");
>>>>>>>>>     perm(0640);
>>>>>>>>>     time-reap(30);
>>>>>>>>>     mark-freq(10);
>>>>>>>>>     stats-freq(0);
>>>>>>>>>     bad-hostname("^gconfd$");
>>>>>>>>>     flush-lines(100);
>>>>>>>>>     log-fifo-size(1000);
>>>>>>>>>     };
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> *destination d_elastic_default_0 {    elasticsearch2(
>>>>>>>>> cluster("myelastic")        cluster-url("https://myelastic.logs:9200
>>>>>>>>> <https://myelastic.logs:9200>")        client_mode("https")
>>>>>>>>> index("default")        type("log")        flush-limit(1)
>>>>>>>>> disk-buffer(            mem-buf-size(16M)
>>>>>>>>> disk-buf-size(16M)            reliable(yes)
>>>>>>>>> dir("/syslog-ng/log")        )        http-auth-type("clientcert")
>>>>>>>>> java-keystore-filepath("/etc/syslog-ng/certificates/syslog-relay.jks")
>>>>>>>>> java-keystore-password("XXXXXX")
>>>>>>>>> java-truststore-filepath("/etc/syslog-ng/certificates/ca-bundle.jks")
>>>>>>>>> java-truststore-password("XXXXXXXXXX")    );};*
>>>>>>>>>
>>>>>>>>> - The dir "/syslog-ng/log" is mapped to a path "/tmp/buffer" from
>>>>>>>>> the host where the docker container is running, so when I kill the docker
>>>>>>>>> container, the buffer file is not lost.
>>>>>>>>> - I've set flush-limit to 1 because I thought that I may lost 1
>>>>>>>>> message only as much.
>>>>>>>>>
>>>>>>>>> This architecture is working fine (flush-limit=1 makes very slow,
>>>>>>>>> but for this test is ok), but if I kill the syslog-relay docker container,
>>>>>>>>> wait 5 to 10 seconds and start it again from scratch, I can see that
>>>>>>>>> several hundreds of logs are missing in elasticsearch. I check it by
>>>>>>>>> stopping the logger service and letting syslog-ng agent & relay to finish
>>>>>>>>> the process enqueued messages.
>>>>>>>>>
>>>>>>>>> I can see in the syslog-agent stats that all logs messages have
>>>>>>>>> been processed, so it seems the problem is on the syslog-relay.
>>>>>>>>>
>>>>>>>>> Is this behaviour expected? If so, how can I protect against loss
>>>>>>>>> of messages in case of a syslog-relay docker container unexpected kill?
>>>>>>>>>
>>>>>>>>> Thanks in advance.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>>
>>>>>>>>> | Jose Angel Santiago
>>>>>>>>>
>>>>>>>>> [image: Logo_signature2.png] <http://www.stratio.com/>
>>>>>>>>>
>>>>>>>>> Vía de las dos Castillas, 33, Ática 4, 3ª Planta
>>>>>>>>>
>>>>>>>>> 28224 Pozuelo de Alarcón, Madrid, Spain
>>>>>>>>>
>>>>>>>>> +34 918 286 473 <+34%20918%2028%2064%2073> | www.stratio.com
>>>>>>>>> <https://twitter.com/stratiobd>
>>>>>>>>> <https://www.linkedin.com/company/stratiobd>
>>>>>>>>> <https://www.youtube.com/c/StratioBD>
>>>>>>>>>
>>>>>>>>> ____________________________________________________________
>>>>>>>>> __________________
>>>>>>>>> Member info: https://lists.balabit.hu/mailman/listinfo/syslog-ng
>>>>>>>>> Documentation: http://www.balabit.com/support
>>>>>>>>> /documentation/?product=syslog-ng
>>>>>>>>> FAQ: http://www.balabit.com/wiki/syslog-ng-faq
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>> ____________________________________________________________
>>>>>>>> __________________
>>>>>>>> Member info: https://lists.balabit.hu/mailman/listinfo/syslog-ng
>>>>>>>> Documentation: http://www.balabit.com/support
>>>>>>>> /documentation/?product=syslog-ng
>>>>>>>> FAQ: http://www.balabit.com/wiki/syslog-ng-faq
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>>
>>>>>>> | Jose Angel Santiago
>>>>>>>
>>>>>>> [image: Logo_signature2.png] <http://www.stratio.com/>
>>>>>>>
>>>>>>> Vía de las dos Castillas, 33, Ática 4, 3ª Planta
>>>>>>>
>>>>>>> 28224 Pozuelo de Alarcón, Madrid, Spain
>>>>>>>
>>>>>>> +34 918 286 473 <+34%20918%2028%2064%2073> | www.stratio.com
>>>>>>> <https://twitter.com/stratiobd>
>>>>>>> <https://www.linkedin.com/company/stratiobd>
>>>>>>> <https://www.youtube.com/c/StratioBD>
>>>>>>> ____________________________________________________________
>>>>>>> __________________
>>>>>>> Member info: https://lists.balabit.hu/mailman/listinfo/syslog-ng
>>>>>>> Documentation: http://www.balabit.com/support
>>>>>>> /documentation/?product=syslog-ng
>>>>>>> FAQ: http://www.balabit.com/wiki/syslog-ng-faq
>>>>>>>
>>>>>>>
>>>>>> ____________________________________________________________
>>>>>> __________________
>>>>>> Member info: https://lists.balabit.hu/mailman/listinfo/syslog-ng
>>>>>> Documentation: http://www.balabit.com/support
>>>>>> /documentation/?product=syslog-ng
>>>>>> FAQ: http://www.balabit.com/wiki/syslog-ng-faq
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>>
>>>>> | Jose Angel Santiago
>>>>>
>>>>> [image: Logo_signature2.png] <http://www.stratio.com/>
>>>>>
>>>>> Vía de las dos Castillas, 33, Ática 4, 3ª Planta
>>>>>
>>>>> 28224 Pozuelo de Alarcón, Madrid, Spain
>>>>>
>>>>> +34 918 286 473 | www.stratio.com
>>>>> <https://twitter.com/stratiobd>
>>>>> <https://www.linkedin.com/company/stratiobd>
>>>>> <https://www.youtube.com/c/StratioBD>
>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>>
>>>> | Jose Angel Santiago
>>>>
>>>> [image: Logo_signature2.png] <http://www.stratio.com/>
>>>>
>>>> Vía de las dos Castillas, 33, Ática 4, 3ª Planta
>>>>
>>>> 28224 Pozuelo de Alarcón, Madrid, Spain
>>>>
>>>> +34 918 286 473 | www.stratio.com
>>>> <https://twitter.com/stratiobd>
>>>> <https://www.linkedin.com/company/stratiobd>
>>>> <https://www.youtube.com/c/StratioBD>
>>>>
>>>> ____________________________________________________________
>>>> __________________
>>>> Member info: https://lists.balabit.hu/mailman/listinfo/syslog-ng
>>>> Documentation: http://www.balabit.com/support
>>>> /documentation/?product=syslog-ng
>>>> FAQ: http://www.balabit.com/wiki/syslog-ng-faq
>>>>
>>>>
>>>>
>>>
>>> ____________________________________________________________
>>> __________________
>>> Member info: https://lists.balabit.hu/mailman/listinfo/syslog-ng
>>> Documentation: http://www.balabit.com/support
>>> /documentation/?product=syslog-ng
>>> FAQ: http://www.balabit.com/wiki/syslog-ng-faq
>>>
>>>
>>>
>>
>>
>> --
>>
>> | Jose Angel Santiago
>>
>> [image: Logo_signature2.png] <http://www.stratio.com/>
>>
>> Vía de las dos Castillas, 33, Ática 4, 3ª Planta
>>
>> 28224 Pozuelo de Alarcón, Madrid, Spain
>>
>> +34 918 286 473 | www.stratio.com
>> <https://twitter.com/stratiobd>
>> <https://www.linkedin.com/company/stratiobd>
>> <https://www.youtube.com/c/StratioBD>
>>
>
>
>
> --
>
> | Jose Angel Santiago
>
> [image: Logo_signature2.png] <http://www.stratio.com/>
>
> Vía de las dos Castillas, 33, Ática 4, 3ª Planta
>
> 28224 Pozuelo de Alarcón, Madrid, Spain
>
> +34 918 286 473 | www.stratio.com
> <https://twitter.com/stratiobd>
> <https://www.linkedin.com/company/stratiobd>
> <https://www.youtube.com/c/StratioBD>
>
> ____________________________________________________________
> __________________
> Member info: https://lists.balabit.hu/mailman/listinfo/syslog-ng
> Documentation: http://www.balabit.com/support/documentation/?product=
> syslog-ng
> FAQ: http://www.balabit.com/wiki/syslog-ng-faq
>
>
>
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