日志收集分析工具logstash + elasticsearch

Your logs are your data: logstash + elasticsearch

by Andrey Redkoon February 25th, 2013| Filed in: Enterprise JavaTags: Elasticsearch,Logging,Logstash

Topic of today’s post stays a bit aside from day-to-day coding and development but nonetheless covers a very important subject: our application log files. Our apps do generate enormous amount of logs which if done right are extremely handy for problems troubleshooting. It’s not a big deal if you have a single application up and running, but nowadays apps, particularity webapps, run on hundreds of servers. With such a scale figuring out where is a problem becomes a challenge. Wouldn’t it be nice to have some kind of a view which aggregates all logs from all our running applications into single dashboard so we could see a whole picture constructed from the pieces? Please welcome:Logstash, the logs aggregation framework.
 
 
 
Although it’s not the only solution available, I found Logstash to be very easy to use and extremely simple to integrate. To start with, we don’t even need to do anything on the application side,Logstash can do all the job for us. Let me introduce the sample project: standalone Java application which has some multithreading activity going on. There is a logging to the file configured using greatLogback library (SLF4J could be used as a seamless replacement). The POM file looks pretty simple:

<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemalocation="http://maven.apache.org/POM/4.0.0http://maven.apache.org/xsd/maven-4.0.0.xsd">

02    <modelversion>4.0.0</modelversion>

03 

04    <groupid>com.example</groupid>

05    <artifactid>logstash</artifactid>

06    <version>0.0.1-SNAPSHOT</version>

07    <packaging>jar</packaging>

08 

09    <properties>

10        <project.build.sourceencoding>UTF-8</project.build.sourceencoding>

11        <logback.version>1.0.6</logback.version>

12    </properties>

13 

14    <dependencies>

15        <dependency>

16            <groupid>ch.qos.logback</groupid>

17            <artifactid>logback-classic</artifactid>

18            <version>${logback.version}</version>

19        </dependency>

20   

21        <dependency>

22            <groupid>ch.qos.logback</groupid>

23            <artifactid>logback-core</artifactid>

24            <version>${logback.version}</version>

25        </dependency>

26    </dependencies>

27  

28    <build>

29        <plugins>

30            <plugin>

31                <groupid>org.apache.maven.plugins</groupid>

32                <artifactid>maven-compiler-plugin</artifactid>

33                <version>3.0</version>

34                <configuration>

35                    <source>1.7

36                    <target>1.7</target>

37                </configuration>

38            </plugin>

39        </plugins>

40    </build>

41</project>And there is only one Java class called Starter which uses Executors services to do some work concurrently. For sure, each thread does some logging and from time to time there is an exception thrown.

01package com.example.logstash;

02 

03import java.util.ArrayList;

04import java.util.Collection;

05import java.util.Random;

06import java.util.concurrent.Callable;

07import java.util.concurrent.ExecutionException;

08import java.util.concurrent.ExecutorService;

09import java.util.concurrent.Executors;

10import java.util.concurrent.Future;

11import java.util.concurrent.TimeUnit;

12import java.util.concurrent.TimeoutException;

13 

14import org.slf4j.Logger;

15import org.slf4j.LoggerFactory;

16 

17public classStarter {

18    privatefinal static Logger log = LoggerFactory.getLogger( Starter.class);

19 

20    publicstatic void main( String[] args ) {

21        finalExecutorService executor = Executors.newCachedThreadPool();

22        finalCollection< Future< Void > > futures = newArrayList< Future< Void > >();

23        finalRandom random = new Random();

24 

25        for(int i = 0; i <10; ++i ) {

26            futures.add(

27                executor.submit(

28                    newCallable< Void >() {

29                        publicVoid call() throws Exception {

30                            intsleep = Math.abs( random.nextInt( 10000) % 10000 );

31                            log.warn('Sleeping for ' + sleep + 'ms' );

32                            Thread.sleep( sleep );

33                            returnnull;

34                        }

35                    }

36                )

37            );

38        }

39 

40        for(final Future< Void > future: futures ) {

41            try{

42                Void result = future.get(3, TimeUnit.SECONDS );

43                log.info('Result ' + result );

44            }catch (InterruptedException | ExecutionException | TimeoutException ex ) {

45                log.error( ex.getMessage(), ex );

46            }  

47        }

48    }

49}

The idea is to demonstrate not only simple one-line logging events but famous Java stack traces. As every thread sleeps for random time interval, it causes TimeoutException to be thrown whenever the result of computation is being asked from the underlying future object and taken more than 3 seconds to return. The last part is Logback configuration (logback.xml):

01<configurationscan="true"scanperiod="5 seconds">

02    <appendername="FILE"class="ch.qos.logback.core.FileAppender">

03        <file>/tmp/application.log</file>

04        <append>true</append>

05        <encoder>

06            <pattern>[%level] %d{yyyy-MM-dd HH:mm:ss.SSS} [%thread] %logger{36} - %msg%n</pattern>

07     </encoder>

08    </appender>

09 

10    <rootlevel="INFO">

11        <appender-refref="FILE">

12    </appender-ref></root>

13</configuration>

And we are good to go! Please note that file path /tmp/application.log corresponds toc:\tmp\application.log on Windows. Running our application would fill log file with something like that:

01[WARN] 2013-02-19 19:26:03.175 [pool-2-thread-1] com.example.logstash.Starter - Sleepingfor 2506ms

02[WARN] 2013-02-19 19:26:03.175 [pool-2-thread-4] com.example.logstash.Starter - Sleepingfor 9147ms

03[WARN] 2013-02-19 19:26:03.175 [pool-2-thread-9] com.example.logstash.Starter - Sleepingfor 3124ms

04[WARN] 2013-02-19 19:26:03.175 [pool-2-thread-3] com.example.logstash.Starter - Sleepingfor 6239ms

05[WARN] 2013-02-19 19:26:03.175 [pool-2-thread-5] com.example.logstash.Starter - Sleepingfor 4534ms

06[WARN] 2013-02-19 19:26:03.175 [pool-2-thread-10] com.example.logstash.Starter - Sleepingfor 1167ms

07[WARN] 2013-02-19 19:26:03.175 [pool-2-thread-7] com.example.logstash.Starter - Sleepingfor 7228ms

08[WARN] 2013-02-19 19:26:03.175 [pool-2-thread-6] com.example.logstash.Starter - Sleepingfor 1587ms

09[WARN] 2013-02-19 19:26:03.175 [pool-2-thread-8] com.example.logstash.Starter - Sleepingfor 9457ms

10[WARN] 2013-02-19 19:26:03.176 [pool-2-thread-2] com.example.logstash.Starter - Sleepingfor 1584ms

11[INFO] 2013-02-19 19:26:05.687 [main] com.example.logstash.Starter - Result null

12[INFO] 2013-02-19 19:26:05.687 [main] com.example.logstash.Starter - Result null

13[ERROR] 2013-02-19 19:26:08.695 [main] com.example.logstash.Starter - null

14java.util.concurrent.TimeoutException: null

15 at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:258) ~[na:1.7.0_13]

16 at java.util.concurrent.FutureTask.get(FutureTask.java:119) ~[na:1.7.0_13]

17 at com.example.logstash.Starter.main(Starter.java:43) ~[classes/:na]

18[ERROR] 2013-02-19 19:26:11.696 [main] com.example.logstash.Starter - null

19java.util.concurrent.TimeoutException: null

20 at java.util.concurrent.FutureTask$Sync.innerGet(FutureTask.java:258) ~[na:1.7.0_13]

21 at java.util.concurrent.FutureTask.get(FutureTask.java:119) ~[na:1.7.0_13]

22 at com.example.logstash.Starter.main(Starter.java:43) ~[classes/:na]

23[INFO] 2013-02-19 19:26:11.696 [main] com.example.logstash.Starter - Result null

24[INFO] 2013-02-19 19:26:11.696 [main] com.example.logstash.Starter - Result null

25[INFO] 2013-02-19 19:26:11.697 [main] com.example.logstash.Starter - Result null

26[INFO] 2013-02-19 19:26:12.639 [main] com.example.logstash.Starter - Result null

27[INFO] 2013-02-19 19:26:12.639 [main] com.example.logstash.Starter - Result null

28[INFO] 2013-02-19 19:26:12.639 [main] com.example.logstash.Starter - Result null

Now let’s see what Logstash can do for us. From the download section, we get the single JAR file:logstash-1.1.9-monolithic.jar. That’s all we need for now. Unfortunately, becauseof this bug on Windows we have to expand logstash-1.1.9-monolithic.jar somewhere, f.e. intologstash-1.1.9-monolithic folder. Logstash has just three concepts: inputs, filters andoutputs. Those are very well explained into the documentation. In our case, the input is application’s log file, c:\tmp\application.log. But what would be the output?ElasticSearch seems to be an excellent candidate for that: let’s have our logs indexed and searchable any time. Let’s download and run it:

1elasticsearch.bat -Des.index.store.type=memory -Des.network.host=localhost

Now we are ready to integrate Logstash which should tail our log file and feed it directly to ElasticSearch. Following configuration does exactly that (logstash.conf):

01input {

02    file {

03        add_field => ['host', 'my-dev-host']

04        path =>'c:\tmp\application.log'

05        type =>'app'

06        format =>'plain'

07    }

08}

09 

10output {

11    elasticsearch_http {

12        host =>'localhost'

13        port =>9200

14        type =>'app'

15        flush_size =>10

16    }

17}

18 

19filter {

20    multiline {

21        type =>'app'

22        pattern =>'^[^\[]'

23        what =>'previous' 

24    }

25}

It might look not very clear on first glance but let me explain what is what. So the input isc:\tmp\application.log, which is a plain text file (format => ‘plain’). Thetype => ‘app’ serves as simple marker so the different types of inputs could be routed to outputs through filters with the same type. Theadd_field => [ ‘host’, ‘my-dev-host’ ] allows to inject additional arbitrary data into the incoming stream, f.e. hostname.

Output is pretty clear: ElasticSearch over HTTP, port 9200 (default settings). Filters need a bit of magic, all because of Java stack traces. Themultiline filter will glue the stack trace to the log statement it belongs to so it will be stored as a single (large) multiline. Let’s runLogstash:

1java -cp logstash-1.1.9-monolithic logstash.runner agent -f logstash.conf

Great! Now whenever we run our application, Logstash will watch the log file, filter it property and send out directly toElasticSearch. Cool, but how can we do the search or at least see what kind of data do we have? ThoughElasticSearch has awesome REST API, we can use another excellent project, Kibana, web UI front-end for ElasticSearch. Installation is very straightforward and seamless. After a few necessary steps, we haveKibana up and running:

1ruby kibana.rb

By default, Kibana provides the web UI available on port 5601, let’s point our browser to it,http://localhost:5601/ and we should see something like that (please click on image to enlarge):

All our logs statements complemented by hostname are just there. Exceptions (with stack traces) are coupled with the related log statement. Log levels, timestamps, everything is being shown. Fulltext search is available out-of-the box, thanks toElasticSearch.

It’s all awesome but our application is very simple. Would this approach work across multi-server / multi-application deployment? I am pretty sure it will work just fine.Logstash’s integration with Redis, ZeroMQ, RabbitMQ, … allows to capture logs from tens of different sources and consolidate them in one place. Thanks a lot,Logstash guys!
 

Reference: Your logs are your data: logstash + elasticsearch from ourJCG partner Andrey Redko at theAndriy Redko {devmind} blog.