Vibe

Vibe is a simplistic approach to Java application monitoring. Vibe can be used to create probes, sample metrics over time and collect events. This information can then be exported over backends, allowing it to be accessed over JMX, sent to services such as InfluxDB, logged or e-mailed.

Licensed under Apache 2.0.

/*
 * Create an instance make metrics available over JMX.
 */
Vibe vibe = Vibe.builder()
  .withBackend(
    JmxBackend.builder().build()
  )
  .build();

/*
 * Export CPU usage of the JVM.
 */
vibe.export(JvmProbes.cpuUsage())
  .at("jvm", "cpu")
  .done();

Using

Vibe requires at least Java 9. The latest version is 0.4.0.

Using Maven:

<dependency>
  <groupId>se.l4.vibe</groupId>
  <artifactId>vibe-api</artifactId>
  <version>0.4.0</version>
</dependency>

Probes and sampling

Probes are the most basic building block in Vibe. Probes can be created to read any type of value and come into two variants, Probe are probes that directly read a value and SampledProbe that require sampling to be able to read a value.

Standard probes

Vibe comes with a few standard probes, such as JVM probes via the class JvmProbes:

SampledProbe<Double> cpuUsage = JvmProbes.cpuUsage();
Probe<Double> heapUsage = JvmProbes.heapMemoryAsFraction();

Implementing a probe

Probes can return any Number (such as integers, longs, floats, doubles etc), Boolean, String or object that implements Snapshot.

`Probe`

Probe is a functional interface with one method that should return the probed value.

A small probe that reads a single value might look like this:

class ThreadPoolExecutorActiveCountProbe implements Probe<Integer> {
  private final ThreadPoolExecutor executor;

  public ThreadPoolExecutorActiveCountProbe(ThreadPoolExecutor executor) {
    this.executor = executor;
  }

  public Integer read() {
    return executor.getActiveCount();
  }
}

Or more simply:

ThreadPoolExecutor executor = ...;

Probe<Integer> probe = executor::getActiveCount;

`SampledProbe`

SampledProbe works as a factory for instances of Sampler that perform the actual sampling. This allows sampled probes to be exported over different backends or used with several instances of TimeSampler.

A Sampler like a Probe is a functional interface that should return a single value.

class ThreadPoolExecutorCompletedTasksProbe implements SampledProbe<Integer> {
  private final ThreadPoolExecutor executor;

  public ThreadPoolExecutorCompletedTasksProbe(ThreadPoolExecutor executor) {
    this.executor = executor;
  }

  public Sampler<Integer> create() {
    return new Sampler<Integer>() {
      private int lastTotal = 0;

      public Integer sample() {
        int total = executor.getCompletedTaskCount();
        int change = total - lastTotal;
        lastTotal = total;
        return change;
      }
    }
  }
}

In many cases a SampledProbe is easier to create via another Probe with an operation applied to. For example the above class can be simplified to:

Probe<Integer> totalCompletedTasks = executor::getCompletedTaskCount;

SampledProbe<Long> completedTasks = totalCompletedTasks.apply(Change.changeAsLong());

Multiple values

For probes that read several values Probe.merged() and SampleProbe.merged() can be used to create probes that read several values:

ThreadPoolExecutor executor = ...;

Probe<KeyValueMap> probe = Probe.merged()
  .add("maxSize", executor::getMaximumPoolSize)
  .add("size", executor:getPoolSize)
  .add("active", executor::getActiveCount)
  .build();

Sampling a probe

Sampling of a probe is done via Sampler. An instance of Sampler will collect samples at a certain interval (10 seconds by default) if it is has a listener, if it's exported or used by another Vibe object.

Example:

TimeSampler<?> sampler = TimeSampler.forProbe(sampledProbe)
  .withInterval(Duration.ofMinutes(1))
  .build();

It's possible to sample a probe as well using Probe by referencing it's read method:

Probe<Double> probe = ...;

TimeSampler<Double> sampler = TimeSampler.forProbe(probe::read)
  .build();

Modifying probes and samplers

Probes and samplers can have operations applied to them to modify their results. Vibe has operations available for things like calculating the average of a time period, extract minimum and maximum values or detecting the how much something changes.

SampledProbe<Long> maxValue = probe.apply(Range.maxAsLong());

TimeSampler<Double> averageOverFiveMinutes = sampler
  .applyResampling(Average.averageOver(Duration.ofMinutes(5)));

These modified probes and samplers can then be exported or used to create checks.

Events

Events are useful to send specific information to other systems via a backend. The LoggingBackend will log these events, but MailBackend will deliver try to deliver events over e-mail and InfluxDBBackend will push them to an InfluxDB server.

Events<UnauthorizedAccess> events = Events.<UnauthorizedAccess>builder()
  .withSeverity(EventSeverity.WARN)
  .create();

events.register(new UnauthorizedAccess(someImportantInfo));

Checks

Checks are objects that can report if their conditions are met. These can be used a health checks, such as checking every minute if average CPU usage over the last 5 minutes is above a certain value:

Check check = Check.builder()
  .whenProbe(JvmProbes.cpuUsage())
    .withCheckInterval(Duration.ofMinutes(1))
    .apply(Average.averageOver(Duration.ofMinutes(5)))
    .is(Conditions.above(0.9))
  .build();

Checks have listeners that will trigger whenever they change state:

check.addListener(event -> {
  if(event.isConditionsMet()) {
    // Check is passing, so CPU usage is above 90% for the last 5 minutes
    events.register(...);
  } else {
    // Check is not passing
    events.register(...);
  }
});

The default behavior of Check is to only trigger an event when the state of conditions being met changes, but checks can also repeat events:

Check check = Check.builder()
  .whenProbe(JvmProbes.cpuUsage())
    .withCheckInterval(Duration.ofMinutes(1))
    .apply(Average.averageOver(Duration.ofMinutes(5)))
    .is(Conditions.above(0.9))
  .whenMetRepeatEvery(Duration.ofMinutes(30))
  .build();

The above example will repeat the event every 30 minutes as long as conditions are met, which is useful for scenarios where you might want to send reminders. whenUnmetRepeatEvery can be used to do the same for when conditions are not met.

Timing calls

Vibe supports timing of actions, such as monitoring the time it takes for your application to handle a request.

To create a timer:

Timer timer = Timer.builder()
  .build();

To use a timer:

try(Stopwatch stopwatch = timer.start()) {
  // Code to measure here
}

Timers can either be exported directly or the getSnapshotProbe method can be used to export snapshot information:

vibe.export(timer.getSnapshotProbe())
  .at("http", "requests")
  .done();

Timers support estimating percentiles, the easiest way to activate this support is via withBuckets that will sort timings into buckets:

Timer timer = Timer.builder()
  .withBuckets(
    Duration.ofMillis(0), 
    Duration.ofMillis(50),
    Duration.ofMillis(100),
    Duration.ofMillis(200),
    Duration.ofMillis(500),
    Duration.ofMillis(1000)
  )
  .build();

Exporting metrics

Probes, samplers, timers and other objects from Vibe can be exported over different backends.

Create an instance of Vibe:

Vibe vibe = Vibe.builder()
  .withBackend(
    LoggingBackend.builder().logSamples().build()
  )
  .withBackend(
    JmxBackend.builder().build()
  )
  .build();

Export using the export method:

Export<SampledProbe<Double>> exportedCpuUsage = vibe.export(JvmProbes.cpuUsage())
  .at("jvm", "cpu")
  .done();

If the thing you exported is no longer needed it can be removed via remove:

exportedCpuUsage.remove();

Send e-mail on events

When you have started sampling some data with triggers for those you can configure an e-mail backend so that you will receive notifications when things go wrong.

First include the backend:

<dependency>
  <groupId>se.l4.vibe</groupId>
  <artifactId>vibe-backend-mail</artifactId>
  <version>0.4.0</version>
</dependency>

Build a backend with the builder:

MailBackend backend = MailBackend.builder()
  .withSender("system@example.org")
  .withSmtpServer("smtp.example.org")
  .withSubject("{severity} event for {path}")
  .withMinimumSeverity(EventSeverity.WARN)
  .addRecipient("sysadmin@example.org")
  .build();

Sending data to InfluxDB

Samples, timers and events can be exported to InfluxDB.

Dependency:

<dependency>
  <groupId>se.l4.vibe</groupId>
  <artifactId>vibe-backend-influxdb</artifactId>
  <version>0.4.0</version>
</dependency>

For InfluxDB 1.x:

VibeBackend backed = InfluxDBBackend.builder()
  .withUrl("http://localhost:8086")
  .withAuthentication("user", "password")
  .addTag("host", "server-1")
  .v1()
    .withDatabase("metrics")
    .done()
  .build();

For InfluxDB 2.x:

VibeBackend backed = InfluxDBBackend.builder()
  .withUrl("http://localhost:9999")
  .withAuthentication("user", "password")
  .addTag("host", "server-1")
  .v2()
    .withBucket("metrics")
    .withOrganization("org")
    .done()
  .build();

Other notes

The current development version can also be accessed via a Maven snapshot repository. Include the following in your POM:

If you want to you can include this repository to use snapshot releases:

<repository>
  <releases>
    <enabled>false</enabled>
  </releases>
  <snapshots>
    <enabled>true</enabled>
  </snapshots>
  <id>sonatype-nexus-snapshots</id>
  <name>Sonatype Nexus Snapshots</name>
  <url>https://oss.sonatype.org/content/repositories/snapshots</url>
</repository>