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From Otis Gospodnetic <otis.gospodne...@gmail.com>
Subject Re: Import files from a directory on remote machine
Date Wed, 23 Apr 2014 16:13:45 GMT
Hi,

Doesn't Spooling Directory Source require one to drop in files only once
they are no longer being written to?  In other words, this is OK if you
need to process data from files periodically, but what if you want to get
and process data in RT, right after it's added to a file?

Is there an alternative to ExecSource + tail -F for this use case?

Thanks,
Otis
--
Performance Monitoring * Log Analytics * Search Analytics
Solr & Elasticsearch Support * http://sematext.com/


On Wed, Apr 23, 2014 at 11:14 AM, Jeff Lord <jlord@cloudera.com> wrote:

> Hi Otis,
>
> This is pretty clearly stated in the docs.
> For production we would typically recommend the spooling directory source
> as an alternative.
>
> http://flume.apache.org/FlumeUserGuide.html#exec-source
>
> "Warning The problem with ExecSource and other asynchronous sources is
> that the source can not guarantee that if there is a failure to put the
> event into the Channel the client knows about it. In such cases, the data
> will be lost. As a for instance, one of the most commonly requested
> features is the tail -F [file]-like use case where an application writes to
> a log file on disk and Flume tails the file, sending each line as an event.
> While this is possible, there’s an obvious problem; what happens if the
> channel fills up and Flume can’t send an event? Flume has no way of
> indicating to the application writing the log file that it needs to retain
> the log or that the event hasn’t been sent, for some reason. If this
> doesn’t make sense, you need only know this: Your application can never
> guarantee data has been received when using a unidirectional asynchronous
> interface such as ExecSource! As an extension of this warning - and to be
> completely clear - there is absolutely zero guarantee of event delivery
> when using this source. For stronger reliability guarantees, consider the
> Spooling Directory Source or direct integration with Flume via the SDK."
>
> -Jeff
>
>
> On Wed, Apr 23, 2014 at 6:48 AM, Otis Gospodnetic <
> otis.gospodnetic@gmail.com> wrote:
>
>> Hi Jeff,
>>
>> On Thu, Apr 17, 2014 at 1:11 PM, Jeff Lord <jlord@cloudera.com> wrote:
>>
>>> Using the exec source with a tail -f is not considered a production
>>> solution.
>>> It mainly exists for testing purposes.
>>>
>>
>> This statement surprised me.  Is that the general consensus among Flume
>> developers or users or at Cloudera?
>>
>> Is there an alternative recommended for production that provides
>> equivalent functionality?
>>
>> Thanks,
>> Otis
>> --
>> Performance Monitoring * Log Analytics * Search Analytics
>> Solr & Elasticsearch Support * http://sematext.com/
>>
>>
>>
>>
>>
>>>
>>>
>>> On Thu, Apr 17, 2014 at 7:03 AM, Laurance George <
>>> laurance.w.george@gmail.com> wrote:
>>>
>>>> If you can NFS mount that directory to your local machine with flume it
>>>> sounds like what you've listed out would work well.
>>>>
>>>>
>>>> On Thu, Apr 17, 2014 at 2:54 AM, Something Something <
>>>> mailinglists19@gmail.com> wrote:
>>>>
>>>>> If I am going to 'rsync' a file from remote host & copy it to hdfs
via
>>>>> Flume, then why use Flume?  I can rsync & then just do a 'hadoop
fs -put',
>>>>> no?  I must be missing something.  I guess, the only benefit of using
Flume
>>>>> is that I can add Interceptors if I want to.  Current requirements don't
>>>>> need that.  We just want to copy data as is.
>>>>>
>>>>> Here's the real use case:   An application is writing to xyz.log
>>>>> file.  Once this file gets over certain size it gets rolled over to
>>>>> xyz1.log & so on.  Kinda like Log4j.  What we really want is as soon
as a
>>>>> line gets written to xyz.log, it should go to HDFS via Flume.
>>>>>
>>>>> Can I do something like this?
>>>>>
>>>>> 1)  Share the log directory under Linux.
>>>>> 2)  Use
>>>>> test1.sources.mylog.type = exec
>>>>> test1.sources.mylog.command = tail -F /home/user1/shares/logs/xyz.log
>>>>>
>>>>> I believe this will work, but is this the right way?  Thanks for your
>>>>> help.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Wed, Apr 16, 2014 at 5:51 PM, Laurance George <
>>>>> laurance.w.george@gmail.com> wrote:
>>>>>
>>>>>> Agreed with Jeff.  Rsync + cron ( if it needs to be regular) is
>>>>>> probably your best bet to ingest files from a remote machine that
you only
>>>>>> have read access to.  But then again you're sorta stepping outside
of the
>>>>>> use case of flume at some level here as rsync is now basically a
part of
>>>>>> your flume topology.  However, if you just need to back-fill old
log data
>>>>>> then this is perfect!  In fact, it's what I do myself.
>>>>>>
>>>>>>
>>>>>> On Wed, Apr 16, 2014 at 8:46 PM, Jeff Lord <jlord@cloudera.com>wrote:
>>>>>>
>>>>>>> The spooling directory source runs as part of the agent.
>>>>>>> The source also needs write access to the files as it renames
them
>>>>>>> upon completion of ingest. Perhaps you could use rsync to copy
the files
>>>>>>> somewhere that you have write access to?
>>>>>>>
>>>>>>>
>>>>>>> On Wed, Apr 16, 2014 at 5:26 PM, Something Something <
>>>>>>> mailinglists19@gmail.com> wrote:
>>>>>>>
>>>>>>>> Thanks Jeff.  This is useful.  Can the spoolDir be on a different
>>>>>>>> machine?  We may have to setup a different process to copy
files into
>>>>>>>> 'spoolDir', right?  Note:  We have 'read only' access to
these files.  Any
>>>>>>>> recommendations about this?
>>>>>>>>
>>>>>>>>
>>>>>>>> On Wed, Apr 16, 2014 at 5:16 PM, Jeff Lord <jlord@cloudera.com>wrote:
>>>>>>>>
>>>>>>>>>
>>>>>>>>> http://flume.apache.org/FlumeUserGuide.html#spooling-directory-source
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Wed, Apr 16, 2014 at 5:14 PM, Something Something
<
>>>>>>>>> mailinglists19@gmail.com> wrote:
>>>>>>>>>
>>>>>>>>>> Hello,
>>>>>>>>>>
>>>>>>>>>> Needless to say I am newbie to Flume, but I've got
a basic flow
>>>>>>>>>> working in which I am importing a log file from my
linux box to hdfs.  I am
>>>>>>>>>> using
>>>>>>>>>>
>>>>>>>>>> a1.sources.r1.command = tail -F /var/log/xyz.log
>>>>>>>>>>
>>>>>>>>>> which is working like a stream of messages.  This
is good!
>>>>>>>>>>
>>>>>>>>>> Now what I want to do is copy log files from a directory
on a
>>>>>>>>>> remote machine on a regular basis.  For example:
>>>>>>>>>>
>>>>>>>>>> username@machinename:/var/log/logdir/<multiple
files>
>>>>>>>>>>
>>>>>>>>>> One way to do it is to simply 'scp' files from the
remote
>>>>>>>>>> directory into my box on a regular basis, but what's
the best way to do
>>>>>>>>>> this in Flume?  Please let me know.
>>>>>>>>>>
>>>>>>>>>> Thanks for the help.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Laurance George
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> Laurance George
>>>>
>>>
>>>
>>
>

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