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Jaeger and Prometheus Integration

Instructions how to set up local Jaeger and Prometheus, a simple local setup that can be used for testing with support for metrics and traces, that collect telemetry from a Vaadin application with Observability Kit.
Caution
Not production-ready
This setup is intended for local testing only.

Download and Run Jaeger

Jaeger is a tool for collecting traces.

Download Jaeger

Extract the contents of the downloaded archive (tar.gz file). Open a terminal to the Jaeger directory and start Jaeger:

./jaeger-all-in-one

Download and Run Prometheus

Prometheus is a tool for collecting metrics.

Download Prometheus

Extract the contents of the downloaded archive (tar.gz file). Create a Prometheus configuration with a scraper that reads metrics data from the OpenTelemetry exporter:

global:
  scrape_interval: 15s # Default is every 1 minute.

scrape_configs:
  - job_name: 'opentelemetry'
    # metrics_path defaults to '/metrics'
    # scheme defaults to 'http'.
    static_configs:
      - targets: ['localhost:9464']
    # Host and port need to match the
    # OpenTelemetry prometheus exporter configuration

Open a terminal to the Prometheus directory and start Prometheus with the configuration file:

./prometheus --config.file=/PATH/TO/config.yml

Remember to substitute the correct path to the config.yml file.

Observability Kit Configuration

Create a new properties file named agent.properties and add the following lines to it:

otel.traces.exporter=jaeger
otel.exporter.jaeger.endpoint=http://localhost:14250
otel.metrics.exporter=prometheus
otel.exporter.prometheus.host=0.0.0.0
otel.exporter.prometheus.port=9464

Running the App

Run the application using the Java binary and pass the respective arguments for the Java agent and the agent configuration:

java -javaagent:PATH/TO/vaadin-opentelemetry-javaagent-VERSION.jar \
     -Dotel.javaagent.configuration-file=PATH/TO/agent.properties \
     -jar myapp.jar
Note
Replace placeholder paths and version
Remember to correct the path to the agent.properties file, as well as the path and version of the Observability Kit .jar file.

Viewing Traces in Jaeger

The default address for the Jaeger user interface is http://localhost:16686. From there you can select your service name – vaadin by default – from the Service field and click the Find Traces button.

The default time period to search is within the last hour. To search further back, select a time period from the Lookback field.

The default number of results is 20. To see more results, increase the value in the Limit Results field.

On the right, there is now a graph of timeline versus duration. From there you can see events that are causing delays, expressed by larger circles, or errors, expressed by red circles. Clicking one of the circles opens the trace detail page.

A list of the root spans is also available. Each span shows the duration relative to the other root spans, how many nested spans it contains, and how many errors. Once again, clicking on an item opens up the trace detail page.

Trace Detail

The trace detail page has a tree list showing the root span and all nested spans. If any of the spans has an error, it’s be marked by a red exclamation (!) icon.

For each of the spans, you can view more details by clicking on the row. In the span details, you can expand Tags to view attributes for the span. Vaadin-specific attributes are detailed in the reference page. If there has been an error, you can find any related stack traces under Logs.

Viewing Metrics in Prometheus

The default address for the Prometheus user interfaces is http://localhost:9090. Enter a metric name into the search field and click Execute.

If you don’t know the metric name, you can use the metrics explorer, by clicking the Earth icon next to Execute. This provides an alphabetical list of available metrics.

To view the results as a graph, click the Graph tab.