OpenTracing Example

You can find the source code here.

Firstly, start Jaeger by running the following command:

docker run --rm -it \
  -e COLLECTOR_ZIPKIN_HOST_PORT=:9411 \
  -p 5775:5775/udp \
  -p 6831:6831/udp \
  -p 6832:6832/udp \
  -p 5778:5778 \
  -p 16686:16686 \
  -p 14268:14268 \
  -p 9411:9411 \
  jaegertracing/all-in-one:1.36

To check if it's running properly visit Jaeger UI. More info can be found here.

Our application contains two services:

1. Proxy service
2. Backend service

Proxy Service

Represents the entry point of the distributed system example. It exposes the /statuses endpoint which returns a list of system's services statuses.

The service consists of ProxyHttpServer and ProxyHttpApp.

ProxyApp

In order to start the service run:

sbt "opentracingExample/runMain zio.telemetry.opentracing.example.ProxyApp"

The console should output

running zio.telemetry.opentracing.example.ProxyApp

if the server has been started properly.

ProxyHttpApp

Provides the implementation of the service, which returns the status of the backend service and the proxy service itself. Client is used to retrieve the status of the backend service.

This is also where the tracing of the application is done, by collecting the timings and logging things such as the span type and the HTTP method. The context is injected into a carrier, and passed along to the backend through Client, where a child span is created, and logging of the backend service is done.

Backend Service

Represents the "internal" service of the system. It exposes the /status endpoint which returns the status of the backend service.

The service consists of BackendServer and BackendApp.

BackendApp

In order to start the service run:

sbt "opentracingExample/runMain zio.telemetry.opentracing.example.BackendApp"

The console should output

running zio.telemetry.opentracing.example.BackendApp

if the server has been started properly.

BackendHttpApp

Provides the implementation of the service, which is to simply return the status of the backend service.

Status

final case class Status(name: String, status: String)

Represents the status of a service.

Statuses

final case class Statuses(data: List[Status]) extends AnyVal

Represents the statuses of a number of services.

Configuration

Configuration is given in application.conf.

Running

After both services are properly started, running the following command

curl -X GET http://localhost:8080/statuses

should return the following response:

{"data":[{"name":"backend","status":"up"},{"name":"proxy","status":"up"}]}

Simultaneously, it will create trace that will be stored in Jaeger backend.