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Telemetry with OpenTelemetry and Micrometer

This sample builds on top of sample 04.0-file-transfer to show how you can:

  • generate traces with OpenTelemetry and collect and visualize them with Jaeger.
  • automatically collect metrics from infrastructure, server endpoints and client libraries with Micrometer and visualize them with Prometheus.

For this, this sample uses the Open Telemetry Java Agent, which dynamically injects bytecode to capture telemetry from several popular libraries and frameworks.

In order to visualize and analyze the traces and metrics, we use OpenTelemetry exporters to export data into the Jaeger tracing backend and a Prometheus endpoint.

Prerequisites

Download the opentelemetry-javaagent.jar and place it in the root folder of this sample.

Run the sample

We will use a single docker-compose to run the consumer, the provider, and a Jaeger backend. Let's have a look to the docker-compose.yaml. We created a consumer and a provider service with entry points specifying the OpenTelemetry Java Agent as a JVM parameter. In addition, the Jaeger exporter is configured using environmental variables as required by OpenTelemetry. The Prometheus exporter is configured to expose a Prometheus metrics endpoint.

To run the consumer, the provider, and Jaeger execute the following commands in the project root folder:

./gradlew samples:04.3-open-telemetry:consumer:build samples:04.3-open-telemetry:provider:build
docker-compose -f samples/04.3-open-telemetry/docker-compose.yaml up --abort-on-container-exit

Once the consumer and provider are up, start a contract negotiation by executing:

curl -X POST -H "Content-Type: application/json" -d @samples/04.0-file-transfer/contractoffer.json "http://localhost:9191/api/negotiation?connectorAddress=http://provider:8282/api/v1/ids/data"

The contract negotiation causes an HTTP request sent from the consumer to the provider connector, followed by another message from the provider to the consumer connector.

You can access the Jaeger UI on your browser at http://localhost:16686. In the search tool, we can select the service consumer and click on Find traces. A trace represents an event and is composed of several spans. You can inspect details on the spans contained in a trace by clicking on it in the Jaeger UI.

OkHttp and Jetty are part of the libraries and frameworks that OpenTelemetry can capture telemetry from. We can observe spans related to OkHttp and Jetty as EDC uses both frameworks internally. The otel.library.name tag of the different spans indicates the framework each span is coming from.

You can access the Prometheus UI on your browser at http://localhost:9090. Click the globe icon near the top right corner (Metrics Explorer) and select a metric to display. Metrics include System (e.g. CPU usage), JVM (e.g. memory usage), Executor service (call timings and thread pools), and the instrumented OkHttp, Jetty and Jersey libraries (HTTP client and server).

Using another monitoring backend

Other monitoring backends can be plugged in easily with OpenTelemetry. For instance, if you want to use Azure Application Insights instead of Jaeger, you can replace the OpenTelemetry Java Agent with the Application Insights Java Agent, which has to be stored in the root folder of this sample as well. The only additional configuration required are the APPLICATIONINSIGHTS_CONNECTION_STRING and APPLICATIONINSIGHTS_ROLE_NAME env variables:

  consumer:
    image: openjdk:17-jdk-slim-buster
    environment:
      APPLICATIONINSIGHTS_CONNECTION_STRING: <your-connection-string>
      APPLICATIONINSIGHTS_ROLE_NAME: consumer
      # optional: increase log verbosity (default level is INFO)
      APPLICATIONINSIGHTS_INSTRUMENTATION_LOGGING_LEVEL: DEBUG
      WEB_HTTP_PORT: 8181
      WEB_HTTP_PATH: /api
      WEB_HTTP_DATA_PORT: 8182
      WEB_HTTP_DATA_PATH: /api/v1/data
      IDS_WEBHOOK_ADDRESS: http://consumer:8181
    volumes:
      - ../:/samples
    ports:
      - 9191:8181
      - 9192:8182
    entrypoint: java
      -javaagent:/samples/04.3-open-telemetry/applicationinsights-agent-3.2.8.jar
      -Djava.util.logging.config.file=/samples/04.3-open-telemetry/logging.properties
      -jar /samples/04.3-open-telemetry/consumer/build/libs/consumer.jar

The Application Insights Java agent will automatically collect metrics from Micrometer, without any configuration needed.

Provide your own OpenTelemetry implementation

In order to provide your own OpenTelemetry implementation, you have to "deploy an OpenTelemetry service provider on the class path":

  • Create a module containing your OpenTelemetry implementation.
  • Add a file in the resource directory META-INF/services. The file should be called io.opentelemetry.api.OpenTelemetry.
  • Add to the file the fully qualified name of your custom OpenTelemetry implementation class.

EDC uses a ServiceLoader to load an implementation of OpenTelemetry. If it finds an OpenTelemetry service provider on the class path it will use it, otherwise it will use the registered global OpenTelemetry. You can look at the section Deploying service providers on the class path of the ServiceLoader documentation to have more information about service providers.