run ./mvnw clean install to build the two Spring Boot applications (api-service and customer-service)
run LOGZIO_REGION=<YOUR_LOGZIO_REGION> LOGZIO_TRACES_TOKEN=<YOUR_LOGZIO_TRACING_TOKEN> docker-compose up --build
call http://localhost:8080/customers/<ID> (where ID is a number from 1 to 50)

The above HTTP call goes to the api-service, which will call the customer-service for additional information. This will create a trace across both services, as should be evident in the logs with the same trace id.

The docker-compose command also starts up an OpenTelemetry Collector, to which the Spring Boot apps send their traces. The OpenTelemetry Collector, in turn, sends the traces to Logz.io.