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:[email protected]] > Sent: Friday, October 26, 2012 9:05 AM > To: [email protected] > 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: > > Logs from syslog across all servers make their way into HDFS. > 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 to > hdfs://namenode/flume/syslog/server=%{host}/facility=%{Facility} > Example: Custom map reduce jobs... > 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: > > 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 > 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. > 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.... > You have to find the latest (ie. the .tmp files) and hadoop fs -tail -f > /path/to/file.tmp > 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: > > Write logs to HDFS directly using 'omhdfs' module, in a format that is both > post-processable and sysadmin-friendly :-) > Write logs to HDFS directly using 'hadoop-fuse-dfs' utility, which has HDFS > mounted as a filesystem. > 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, [email protected] > <Ronald J Thielen.vcf>
