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From Josh West <...@one.com>
Subject Re: Syslog Infrastructure with Flume
Date Tue, 30 Oct 2012 09:47:22 GMT
Very cool.  Hcatalog seems like a nice idea, as otherwise lots of 
thought and planning must go into how one stores their data ... ensuring 
it can be read from all different Apache Hadoop related projects... E.G. 
if you store flume data in an HDFS path with 
/something=partition1/foo=bar, you'll need to use special Pig libraries 
to load the partitions.

Keep us updated please!

On 10/30/2012 12:37 AM, Roshan Naik wrote:
> I am in the process of investigating the possibility of creating  a 
> HCatalog sink for Flume which should be able to handle such use cases. 
> For your use case it could be thought of as a Hive sink. Goal is 
> basically as follows... it would allow multiple flume agents to pump 
> logs into a hive tables. That would make the data query-able without 
> additional manual steps. Data will get added periodically in the form 
> of new partitions to Hive. You would not have to deal with temporary 
> files or manual addition of data into hive.
> -roshan
> On Sun, Oct 28, 2012 at 5:45 PM, Ralph Goers 
> <ralph.goers@dslextreme.com <mailto:ralph.goers@dslextreme.com>> wrote:
>     Since you ask...
>     In our environment our primary concern is audit logs - have have
>     to audit banking transactions as well as changes administrators
>     make. We have a legacy system that needed to be integrated that
>     had records in a form different than what we want stored. We also
>     need to allow administrators to view events as close to real time
>     as possible. Plus we have to aggregate data across 2 data centers.
>     Although we are currently not including web server access logs we
>     plan to integrate them in over time.  We also have requirements
>     from our security team to pass events for their use to ArcSight.
>     1. We have a "log extractor" that receives legacy events as they
>     occur and converts them into our new format and passes them to
>     Flume. All new applications use the Log4j 2 Flume Appender to get
>     data to Flume.
>     2. Flume passes the data to ArcSight for our security team's use.
>     3. We wrote a Flume to Cassandra Sink.
>     4. We wrote our own REST query services to retrieve the data from
>     Cassandra.
>     5. Since we are using DataStax Enterprise version of Cassandra we
>     have also set up "Analytic" nodes that run Hadoop on top of
>     Cassandra. This allows the data to be accessed via normal Hadoop
>     tools for data analytics.
>     6. We have written our own reporting UI component in our
>     Administrative Platform to allow administrators to view activities
>     in real time or to schedule background data collection so users
>     can post process the data on their own.
>     We do not have anything to allow an admin to "tail" the log but it
>     wouldn't be hard at all to write an application to accept Flume
>     events via Avro and display the last "n" events as they arrive.
>     One thing I should point out. We format our events in accordance
>     with RFC 5424 and store that in the Flume event body. We then
>     store all our individual pieces of audit event data in Flume
>     headers fields.  The RFC 5424 message is what we send to ArcSight.
>     The event fields and the compressed body are all stored in
>     individual columns in Cassandra.
>     Ralph
>     On Oct 26, 2012, at 2:06 PM, Ron Thielen wrote:
>>     I am exactly where you are with this, except for the problem of
>>     my not having had time to write a serializer to address the
>>     Hostname Timestamp issue.Questions about the use of Flume in this
>>     manner seem to recur on a regular basis, so it seems a common use
>>     case.
>>     Sorry I cannot offer a solution since I am in your shoes at the
>>     moment, unfortunately looking at storing logs twice.
>>     Ron Thielen
>>     <image001.jpg>
>>     *From:*Josh West [mailto:jsw@one.com <mailto:jsw@one.com>]
>>     *Sent:*Friday, October 26, 2012 9:05 AM
>>     *To:*user@flume.apache.org <mailto:user@flume.apache.org>
>>     *Subject:*Syslog Infrastructure with Flume
>>     Hey folks,
>>     I've been experimenting with Flume for a few weeks now, trying to
>>     determine an approach to designing a reliable, highly available,
>>     scalable system to store logs from various sources, including
>>     syslog.  Ideally, this system will meet the following requirements:
>>      1. Logs from syslog across all servers make their way into HDFS.
>>      2. Logs are stored in HDFS in a manner that is available for
>>         post-processing:
>>           * Example: HIVE partitions - with HDFS Flume Sink, can set
>>             hdfs.path
>>             tohdfs://namenode/flume/syslog/server=%{host}/facility=%{Facility}
>>           * Example: Custom map reduce jobs...
>>      3. Logs are stored in HDFS in a manner that is available for
>>         "reading" by sysadmins:
>>           * During troubleshooting/firefighting, it is quite helpful
>>             to be able to login to a central logging system and tail
>>             -f / grep logs.
>>           * We need to be able to see the logs "live".
>>     Some folks may be wondering why are we choosing Flume for syslog,
>>     instead of something like Graylog2 or Logstash?  The answer is we
>>     will be using Flume + Hadoop for the transport and processing of
>>     other types of data in addition to syslog.  For example,
>>     webserver access logs for post processing and statistical
>>     analysis.  So, we would like to make the most use of the Hadoop
>>     cluster, keeping all logs of all types in one redundant/scalable
>>     solution. Additionally, by keeping both syslog and webserver
>>     access logs in Hadoop/HDFS, we can begin to correlate events.
>>     I've run into some snags while attempting to implement Flume in a
>>     manner that satisfies the requirements listed in the top of this
>>     message:
>>      1. Logs to HDFS:
>>           * I can indeed use the Flume HDFS Sink to reliably write
>>             logs into HDFS.
>>           * Needed to write custom serializer to add Hostname and
>>             Timestamp fields back to syslog messages.
>>           * See: https://issues.apache.org/jira/browse/FLUME-1666
>>      2. Logs to HDFS in manner available for
>>         reading/firefighting/troubleshooting by sysadmins:
>>           * Flume HDFS Sink uses the BucketWriter for recording flume
>>             events to HDFS.
>>           * Creates data files like:
>>             /flume/syslog/server=%{host}/facility=%{Facility}/FlumeData.1350997160213
>>           * Each file is format of FlumeData (or custom prefix)
>>             followed by . followed by unix timestamp of when the file
>>             was created.
>>               o This is somewhat necessary... As you could have
>>                 multiple Flume writers, writing to the same HDFS, the
>>                 files cannot be opened by more than one writer.  So
>>                 each writer should write to its own file.
>>           * Latest file, currently being written to, is suffixed with
>>             ".tmp".
>>           * This approach is not very sysadmin-friendly....
>>               o You have to find the latest (ie. the .tmp files) and
>>                 hadoop fs -tail -f /path/to/file.tmp
>>               o Hadoop's fs -tail -f command first prints the entire
>>                 file's contents, then begins tailing.
>>     So the sum of it all is Flume is awesome for getting syslog (and
>>     other) data into HDFS for post processing, but not the best at
>>     getting it into HDFS in a sysadmin troubleshooting/firefighting
>>     format.  In an ideal world, I have syslog data coming into Flume
>>     via one transport (i.e. SyslogTcp Source or SyslogUDP Source) and
>>     being written into HDFS in a manner that is both post-processable
>>     and sysadmin-friendly, but it looks like this isn't going to happen.
>>     I've thus investigated some alternative approaches to meet the
>>     requirements.  One of these approaches is to have all of my
>>     servers send their syslog messages to a central box running
>>     rsyslog. Then, rsyslog would perform one of the following actions:
>>      1. Write logs to HDFS directly using 'omhdfs' module, in a
>>         format that is both post-processable and sysadmin-friendly :-)
>>      2. Write logs to HDFS directly using 'hadoop-fuse-dfs' utility,
>>         which has HDFS mounted as a filesystem.
>>      3. Write logs to a local filesystem and also replicate logs into
>>         a flume agent, configured with a SyslogSource and HDFS sink.
>>     Option #1 sounds great.  But unfortunately the 'omhdfs' module
>>     for rsyslog isn't working very well.  I've gotten it to login to
>>     Hadoop/HDFS but it has issues creating/appending files.
>>     Additionally, templating is somewhat suspect (ie. making
>>     directories /syslog/someserver/somefacility dynamically).
>>     Option #2 sounds reasonable, but either the HDFS FUSE module
>>     doesn't support append mode (yet) or rsyslog is trying to
>>     create/open the files in a manner not compliant with HDFS.  No
>>     surprise, as we all know HDFS can be somewhat "special" at times
>>     ;-) It's actually no matter anyways... Trying to "tail -f" a file
>>     mounted via HDFS FUSE is rather useless. The data is only and
>>     finally fed to the tail command once a full 64MB (or whatever you
>>     use) block size of data has been written to the file. One would
>>     only be able to use "hadoop fs -tail -f /path/to/log" which has
>>     its own issues mentioned previously.
>>     Option #3 would definitely work.  However, now I'm storing my
>>     logs twice.  Once on some local filesystem and another time in
>>     HDFS.  It works but its not ideal as it's a waste of space.  And
>>     you've probably noticed from this email so far, I'd prefer
>>     the*ideal*solution :-)
>>     *Note*: Astute flumers would probably look at option #3 and
>>     recommend making use of the RollingFileSink in addition to the
>>     HDFSSink. Unfortunately, the RollingFileSink doesn't support
>>     templated/dynamic directory creation like the HDFSSink with its
>>     hdfs.path setting of
>>     "hdfs://namenode/flume/syslog/server=%{host}/facility=%{Facility}".
>>     So what exactly am I asking here?  Well, I'd like to know first
>>     how others are doing this.  A hybrid of rsyslog and Flume?  All
>>     and only Flume?  With custom serializers/interceptors/sinks?  Or
>>     perhaps... how would you recommend I handle this?
>>     Thanks for any and all thoughts you can provide.
>>     -- 
>>     Josh West
>>     Lead Systems Administrator
>>     One.com  <http://One.com>,jsw@one.com  <mailto:jsw@one.com>
>>     <Ronald J  Thielen.vcf>

Josh West
Lead Systems Administrator
One.com, jsw@one.com

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