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From Ahmed Vila <av...@devlogic.eu>
Subject Re: Need suggestion on reliable source for log processing
Date Mon, 27 Oct 2014 10:24:46 GMT
Hi,

In fact, this is not the problem with Flume.

No solution will function reliably for your use case, simply because all of
them will have to do some sort of tail-f or streaming on a file and if they
can't keep up with it (they mostly don't in high speed entry points), they
will drop some entries.
Please, be kind to yourself and plan for failures - if you need to restart
Flume or any other solution then you'll face dropped entries that you'll
not be able to re-ingest easily as in most cases you won't know which ones
you've dropped.


Regards,
Ahmed

On Mon, Oct 27, 2014 at 11:13 AM, SaravanaKumar TR <saran0081986@gmail.com>
wrote:

> Thanks for comments Ahmed.
>
> So from your comments , I consider that flume doesn't have any reliable
> source option for use case provided by me.
>
> If flume can't provide it, can you help me with any other log collector
> solutions which can I consider here to move real time data to HDFS.
>
>
>
> On Mon, Oct 27, 2014 at 3:37 PM, Ahmed Vila <avila@devlogic.eu> wrote:
>
>> Hi,
>>
>> Then, you're out of luck in my opinion, as there is no way other than
>> tail -f.
>> The problem with fail-f is that tail will not wait for source/channel to
>> keep up with it. If Cnannel is full it will back-off to the source and then
>> the source will just stop ingesting.
>>
>> There is a possibility to hack up the tail -f into another file and then
>> custom-rotate that duplicate file.
>> But, I wouldn't recommend such case.
>>
>> Just a side note - If you're operating Java application (Tomcat or
>> similar), then you can create multiple output files via log4j.properties
>> configuration without application itself knowing anything about it.
>>
>> Regards,
>> Ahmed
>>
>>
>> On Mon, Oct 27, 2014 at 10:56 AM, SaravanaKumar TR <
>> saran0081986@gmail.com> wrote:
>>
>>> Ahmed,
>>>
>>> Here in my case , the application will rename the existing file as
>>> <logfile>.yesterdaydate and create a new file as <logfile> at 00:00
AM.
>>>
>>> I can't change the log rotation policy of application for now.So I guess
>>> I should rule out the option of using spooling directory source in my case.
>>>
>>> Can you suggest me with any other options other than spooling dir source.
>>>
>>> Thanks,
>>>
>>> On Mon, Oct 27, 2014 at 3:10 PM, Ahmed Vila <avila@devlogic.eu> wrote:
>>>
>>>> Hi,
>>>>
>>>> It all depends on how log rotation is done and how application
>>>> producing the log file handles log rotation.
>>>> Most of the applications just reopens the log file when it receives a
>>>> kill signal. For example, nginx reopens the log file when it receives USR1
>>>> signal, but it doesn't stop the process. Some applications might restart
as
>>>> a result.
>>>>
>>>> If the application just reopens the log file, then you can change your
>>>> log rotation policy to be per minute.
>>>> In that case logrotate daemon won't satisfy such case, so you'll have
>>>> to make a cron job to do it.
>>>> In such case, you would separate finished logs location and live log
>>>> location so the spooling directory source doesn't freak out about active
>>>> log file being appended.
>>>>
>>>> Anyway, spooling directory source is a way to go, as it will leave log
>>>> files in place, just renamed.
>>>>
>>>> Regards,
>>>> Ahmed
>>>>
>>>>
>>>> On Mon, Oct 27, 2014 at 10:21 AM, SaravanaKumar TR <
>>>> saran0081986@gmail.com> wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> I am using Apache flume 1.5.0.Quick setup explanation here.
>>>>>
>>>>> Source:exec , tail –F command for a logfile.
>>>>>
>>>>> Channel:  file channel
>>>>>
>>>>> Sink: HDFS
>>>>>
>>>>> Use case:to move real time data from logfile to HDFS.
>>>>>
>>>>>
>>>>> It appears like exec is not a reliable source , as we may data loss if
>>>>> channel/source is down.
>>>>>
>>>>>
>>>>> So i tried with other option "spooling directory source" which is
>>>>> mentioned as reliable source.But here I have a single logfile where data
>>>>> gets appended in , so I dont see option of moving the file to spool
>>>>> directory.
>>>>>
>>>>>
>>>>> Can anyone help me with providing any other reliable source option in
>>>>> case where logfile gets appended with data and logfile rotation happens
>>>>> only at the end of the day.
>>>>>
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Saravana
>>>>>
>>>>
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