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Flume, mail # user - Import files from a directory on remote machine


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RE: Import files from a directory on remote machine
Paul Chavez 2014-04-23, 16:52
I would recommend using a scheduled script to create diff files off the log files. I have one that runs against large logs files that roll over on UTC day. It runs once a minute, checkpoints the log, creates a diff a drops it in the spool directory and then cleans up any completed files.

I agree it would be nice if there was a source that implemented this type of functionality in flume (checkpointing and picking new events off a file in use) but this works for now and is a pattern I’ve seen recommended on this list before.

Hope that helps,
Paul
From: Otis Gospodnetic [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, April 23, 2014 9:14 AM
To: [EMAIL PROTECTED]
Subject: Re: Import files from a directory on remote machine

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 <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> 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 <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> wrote:
Hi Jeff,

On Thu, Apr 17, 2014 at 1:11 PM, Jeff Lord <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> 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 <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> 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 <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> 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 <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> 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 <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> 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 <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> 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 <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> wrote:
http://flume.apache.org/FlumeUserGuide.html#spooling-directory-sour