chakra-coder/instana-java-sdk

Open Source Repository for the Instana Java SDK

Instana Java Trace SDK  

Instana automatically instruments well known frameworks for calls coming into a monitored JVM, which we call Entry (also known as Server in OpenTracing), and calls leaving a monitored JVM, which we call Exit (also known as Client). Usually calls pass instrumented code twice: at the start of a request, and at the end. The time elapsed between those two passings is the duration this call took. This duration, along with additional specific metadata is collected in so called Spans.

For the case where Instana does not (yet) know how to instrument a framework, or for monitoring the requests of a very custom application, this SDK can be used.

There is little code needed to enhance monitoring of a custom application. The most common use cases are:

• Adding a new Entry
• Adding a new Exit
• Collecting additional Metadata

Each of those use cases is demonstrated in instana-java-sdk-sample, which contains a Dropwizard based web application, which uses additional custom code. The two classes required are com.instana.sdk.annotation.Span and com.instana.sdk.support.SpanSupport which contain Javadoc explaining their usage.

To enable the SDK in your application, you should add a dependency to the SDK and make sure you package and deploy the SDK jar with your application.

When using maven you can add it with:

<dependency>
  <groupId>com.instana</groupId>
  <artifactId>instana-java-sdk</artifactId>
  <version>1.0.1</version>
</dependency>

To avoid any unwanted interference by scanning for the SDK annotations, the agent requires the following configuration to whitelist packages for SDK usage:

com.instana.plugin.javatrace:
  instrumentation:
    sdk:
      packages:
        - 'com.acme'

By design, the SDK will remain inactive when no Instana agent is monitoring the JVM process. It will also return to inactivity when the Instana agent is stopped. Therefore it is safe to keep it in your application code even when deploying to systems not yet monitored by Instana.

The whole SDK contained in this repository is provided with an MIT License (see LICENSE.md), to allow any use and conflict with strict open source licensing requirements.

Instana Trace Webservice

There is an additional option to generate traces. The Instana Agent offers a WebService/Rest endpoint, which accepts a JSON description of a Span. The most common use case for that is to generate Spans in unmonitored or very custom components. In fact this endpoint allows to submit trace data for any programming language manually. Of course we still work towards a fully automatic and optimized instrumentation.

The endpoint listens on any running agent at http://localhost:42699/com.instana.plugin.generic.trace and accepts the following JSON:

{
  'spanId': <64 bit long>,
  'parentId': <64 bit long>,
  'traceId': <64 bit long>,
  'timestamp': <64 bit long>,
  'duration': <64 bit long>,
  'name' : <string>,
  'type' : <string>,
  'data' : {
    <string> : <string>
  },
  'agent' : <string>
}

spanId is a unique identifier for the span. parentId and traceId are optional and refer to the hierarchy of spans. timestamp and duration are in milliseconds. name can be any string which is used to visualize and group traces and can contain any text, but it is recommended to keep it simple. type is optional, but when given needs to be either ENTRY, EXIT or INTERMEDIATE. data is optional and can contain arbitrary key-value pairs. Behaviour of supplying duplicate keys is unspecified. agent is used in the user interface to indicate what trace agent was used to generate the span and potentially to access trace agent internal fields. When unset it will use ws. Other trace agents provided by Instana already are java, php and node. The field is optional, and only documented for completeness.

The endpoint also accepts a batch of spans, which then need to be given as array:

[
  {
    // span as above
  },
  {
    // span as above
  }
]