Adapts the open-telemetry example for using agents

[fedefernandez]

Based on the Demo example from open-telemetry/opentelemetry-collector-contrib, this PR updates the example to show how to deploy the collector in Agent mode.

The agent collector deployment pattern consists of applications — instrumented with an OpenTelemetry SDK using OpenTelemetry protocol (OTLP) — or other collectors (using the OTLP exporter) that send telemetry signals to a collector instance running with the application or on the same host as the application (such as a sidecar or a daemonset).

Each client-side SDK or downstream collector is configured with a collector location:

Decentralized collector deployment concept
In the app, the SDK is configured to send OTLP data to a collector.
The collector is configured to send telemetry data to one or more backends.

Ref docs

The Animal.kt client uses the opentelemetry library for instrumentation and for sending telemetry data to the opentelemetry collector.

This example presents the typical flow of observability data where multiple OpenTelemetry Collectors can be deployed.

graph TD;
    ClientA-->Collector;
    ClientB-->Collector;
    Collector-->Jaeger;
    Collector-->Zipkin;
    Collector-->Prometheus;

• Clients send data directly to the OpenTelemetry Collector
• The OpenTelemetry Collector Collector then sends the data to the appropriate backend. In the example Jaeger, Zipkin, and Prometheus.

The example uses docker-compose. To run the demo, switch to the server/docker/opentelemetry folder and run:

docker compose up -d

Docker should expose the following backends:

• Jaeger at http://0.0.0.0:16686
• Zipkin at http://0.0.0.0:9411
• Prometheus at http://0.0.0.0:9090

[Montagon]

Great job! 👏

[raulraja]

Thank you @fedefernandez !