# Using OpenTracing

This guide explains how your Quarkus application can utilize OpenTracing to provide distributed tracing for interactive web applications.

| OpenTelemetry is the recommended approach to tracing and telemetry for Quarkus. When Quarkus will upgrade to Eclipse MicroProfile 6, the SmallRye OpenTracing support will be discontinued.

| This technology is considered deprecated. Being deprecated means that this extension is likely to be replaced or removed in a future version of Quarkus. For a full list of possible statuses, check our FAQ entry.

## Prerequisites

To complete this guide, you need:

- Roughly 15 minutes

- An IDE

- JDK 11+ installed with `JAVA_HOME` configured appropriately

- Apache Maven 3.9.3

- A working container runtime (Docker or Podman)

- Optionally the Quarkus CLI if you want to use it

- Optionally Mandrel or GraalVM installed and configured appropriately if you want to build a native executable (or Docker if you use a native container build)

## Architecture

In this guide, we create a straightforward REST application to demonstrate distributed tracing.

## Solution

We recommend that you follow the instructions in the next sections and create the application step by step. However, you can skip right to the completed example.

Clone the Git repository: `git clone https://github.com/quarkusio/quarkus-quickstarts.git`, or download an archive.

The solution is located in the `opentracing-quickstart` directory.

## Creating the Maven project

First, we need a new project. Create a new project with the following command:

CLI

    quarkus create app org.acme:opentracing-quickstart \
        --extension='resteasy-reactive,quarkus-smallrye-opentracing' \
        --no-code
    cd opentracing-quickstart

To create a Gradle project, add the `--gradle` or `--gradle-kotlin-dsl` option.

For more information about how to install and use the Quarkus CLI, see the Quarkus CLI guide.

Maven

    mvn io.quarkus.platform:quarkus-maven-plugin:3.3.0:create \
        -DprojectGroupId=org.acme \
        -DprojectArtifactId=opentracing-quickstart \
        -Dextensions='resteasy-reactive,quarkus-smallrye-opentracing' \
        -DnoCode
    cd opentracing-quickstart

To create a Gradle project, add the `-DbuildTool=gradle` or `-DbuildTool=gradle-kotlin-dsl` option.

For Windows users:

- If using cmd, (don’t use backward slash `\` and put everything on the same line)

- If using Powershell, wrap `-D` parameters in double quotes e.g. `"-DprojectArtifactId=opentracing-quickstart"`

This command generates the Maven project and imports the `smallrye-opentracing` extension, which includes the OpenTracing support and the default Jaeger tracer.

If you already have your Quarkus project configured, you can add the `smallrye-opentracing` extension to your project by running the following command in your project base directory:

CLI

    quarkus extension add 'smallrye-opentracing'

Maven

    ./mvnw quarkus:add-extension -Dextensions='smallrye-opentracing'

Gradle

    ./gradlew addExtension --extensions='smallrye-opentracing'

This will add the following to your build file:

pom.xml

    <dependency>
        <groupId>io.quarkus</groupId>
        <artifactId>quarkus-smallrye-opentracing</artifactId>
    </dependency>

build.gradle

    implementation("io.quarkus:quarkus-smallrye-opentracing")

### Examine the Jakarta REST resource

Create the `src/main/java/org/acme/opentracing/TracedResource.java` file with the following content:

    package org.acme.opentracing;

    import jakarta.ws.rs.GET;
    import jakarta.ws.rs.Path;
    import jakarta.ws.rs.Produces;
    import jakarta.ws.rs.core.MediaType;
    import org.jboss.logging.Logger;

    @Path("/hello")
    public class TracedResource {

        private static final Logger LOG = Logger.getLogger(TracedResource.class);

        @GET
        @Produces(MediaType.TEXT_PLAIN)
        public String hello() {
            LOG.info("hello"); (1)
            return "hello";
        }
    }

1 | The log event carries OpenTracing information as well. In order to print OpenTracing information to the console output, the console log handler with the required OpenTracing event’s keys needs to be defined in the `application.properties` file.

Notice that there is no tracing specific code included in the application. By default, requests sent to this endpoint will be traced without any code changes being required. It is also possible to enhance the tracing information. This can be achieved by SmallRye OpenTracing an implementation of MicroProfile OpenTracing.

### Create the configuration

There are two ways to configure the Jaeger tracer within the application.

The first approach is by providing the properties within the `src/main/resources/application.properties` file:

    quarkus.jaeger.service-name=myservice (1)
    quarkus.jaeger.sampler-type=const (2)
    quarkus.jaeger.sampler-param=1 (3)
    quarkus.log.console.format=%d{HH:mm:ss} %-5p traceId=%X{traceId}, parentId=%X{parentId}, spanId=%X{spanId}, sampled=%X{sampled} [%c{2.}] (%t) %s%e%n (4)

1 | If the `quarkus.jaeger.service-name` property (or `JAEGER_SERVICE_NAME` environment variable) is not provided then a "no-op" tracer will be configured, resulting in no tracing data being reported to the backend.
2 | Set up a sampler that uses a constant sampling strategy.
3 | Sample all requests. Set sampler-param to somewhere between 0 and 1, e.g. 0.50, if you do not wish to sample all requests.
4 | Add trace IDs into log message.

The second approach is to supply the properties as environment variables. These can be specified using `jvm.args` as shown in the following section.

## Run the application

The first step is to start the tracing system to collect and display the captured traces:

    docker run -p 5775:5775/udp -p 6831:6831/udp -p 6832:6832/udp -p 5778:5778 -p 16686:16686 -p 14268:14268 jaegertracing/all-in-one:latest

Now we are ready to run our application. If using `application.properties` to configure the tracer:

CLI

    quarkus dev

Maven

    ./mvnw quarkus:dev

Gradle

    ./gradlew --console=plain quarkusDev

or if configuring the tracer via environment variables:

CLI

    quarkus dev -Djvm.args="-DJAEGER_SERVICE_NAME=myservice -DJAEGER_SAMPLER_TYPE=const -DJAEGER_SAMPLER_PARAM=1"

Maven

    ./mvnw quarkus:dev -Djvm.args="-DJAEGER_SERVICE_NAME=myservice -DJAEGER_SAMPLER_TYPE=const -DJAEGER_SAMPLER_PARAM=1"

Gradle

    ./gradlew --console=plain quarkusDev -Djvm.args="-DJAEGER_SERVICE_NAME=myservice -DJAEGER_SAMPLER_TYPE=const -DJAEGER_SAMPLER_PARAM=1"

Once both the application and tracing system are started, you can make a request to the provided endpoint:

    $ curl http://localhost:8080/hello
    hello

When the first request has been submitted, the Jaeger tracer within the app will be initialized:

    2019-10-16 09:35:23,464 INFO  [io.jae.Configuration] (executor-thread-1) Initialized tracer=JaegerTracer(version=Java-0.34.0, serviceName=myservice, reporter=RemoteReporter(sender=UdpSender(), closeEnqueueTimeout=1000), sampler=ConstSampler(decision=true, tags={sampler.type=const, sampler.param=true}), tags={hostname=localhost.localdomain, jaeger.version=Java-0.34.0, ip=127.0.0.1}, zipkinSharedRpcSpan=false, expandExceptionLogs=false, useTraceId128Bit=false)
    13:20:11 INFO  traceId=1336b2b0a76a96a3, parentId=0, spanId=1336b2b0a76a96a3, sampled=true [or.ac.qu.TracedResource] (executor-thread-63) hello

Then visit the Jaeger UI to see the tracing information.

Hit `CTRL+C` to stop the application.

## Tracing additional methods

REST endpoints are automatically traced. If you need to trace additional methods, you can add the `org.eclipse.microprofile.opentracing.Traced` annotation to CDI bean classes or their non-private methods.

This can be useful to trace incoming requests from non-REST calls (like request coming from a message) or to create spans inside a trace.

Here is an example of a `FrancophoneService` which methods are traced.

    import jakarta.enterprise.context.ApplicationScoped;

    import org.eclipse.microprofile.opentracing.Traced;

    @Traced
    @ApplicationScoped
    public class FrancophoneService {

        public String bonjour() {
            return "bonjour";
        }
    }

| The best way to add OpenTracing capability to reactive messaging based applications is by adding the `Traced` annotation to all incoming methods.

## Additional instrumentation

The OpenTracing API Contributions project offers additional instrumentation that can be used to add tracing to a large variety of technologies/components.

The instrumentation documented in this section has been tested with Quarkus and works in both standard and native mode.

### JDBC

The JDBC instrumentation will add a span for each JDBC queries done by your application, to enable it, add the following dependency to your build file:

pom.xml

    <dependency>
        <groupId>io.opentracing.contrib</groupId>
        <artifactId>opentracing-jdbc</artifactId>
    </dependency>

build.gradle

    implementation("io.opentracing.contrib:opentracing-jdbc")

Then, you need to enable it in the configuration:

    quarkus.datasource.jdbc.tracing=true

`quarkus.datasource.jdbc.tracing` is a build time configuration property: it makes sure all the tracing infrastructure is included in your application.

| This is especially important when building a native executable as we need to make sure the OpenTracing JDBC driver has been registered for reflection, together with the underlying JDBC driver.

The Agroal extension will take care of adjusting the JDBC URL with the `tracing` prefix when tracing is enabled, so you do not have to adjust the JDBC URL yourself.

By default, when `quarkus.datasource.jdbc.tracing` is true, tracing is enabled at runtime but you can explicitly disable it by setting the following property:

    quarkus.datasource.jdbc.tracing.enabled=false

This way, you can have your Quarkus application ready for tracing and toggle JDBC tracing at runtime.

### Kafka

The Kafka instrumentation will add a span for each message sent to or received from a Kafka topic. To enable it, add the following dependency to your build file:

pom.xml

    <dependency>
        <groupId>io.opentracing.contrib</groupId>
        <artifactId>opentracing-kafka-client</artifactId>
    </dependency>

build.gradle

    implementation("io.opentracing.contrib:opentracing-kafka-client")

It contains OpenTracing interceptors that must be registered on Kafka producers and consumers.

If you followed the Kafka guide, the interceptors can be added on the `generated-price` and the `prices` channels as follows:

    # Configure the Kafka sink (we write to it)
    mp.messaging.outgoing.generated-price.connector=smallrye-kafka
    mp.messaging.outgoing.generated-price.topic=prices
    mp.messaging.outgoing.generated-price.value.serializer=org.apache.kafka.common.serialization.IntegerSerializer
    mp.messaging.outgoing.generated-price.interceptor.classes=io.opentracing.contrib.kafka.TracingProducerInterceptor

    # Configure the Kafka source (we read from it)
    mp.messaging.incoming.prices.connector=smallrye-kafka
    mp.messaging.incoming.prices.value.deserializer=org.apache.kafka.common.serialization.IntegerDeserializer
    mp.messaging.incoming.prices.interceptor.classes=io.opentracing.contrib.kafka.TracingConsumerInterceptor

| `interceptor.classes` accept a list of classes separated by a comma.

### MongoDB client

The Mongo Driver instrumentation will add a span for each command executed by your application. To enable it, add the following dependency to your build file:

pom.xml

    <dependency>
        <groupId>io.opentracing.contrib</groupId>
        <artifactId>opentracing-mongo-common</artifactId>
    </dependency>

build.gradle

    implementation("io.opentracing.contrib:opentracing-mongo-common")

It contains the OpenTracing CommandListener that will be registered on the configuration of the mongo client. Following the MongoDB guide, the command listener will be registered defining the config property as follows:

    # Enable tracing commands in mongodb client
    quarkus.mongodb.tracing.enabled=true

### Zipkin compatibility mode

To enable it, add the following dependency to your build file:

pom.xml

    <dependency>
        <groupId>io.jaegertracing</groupId>
        <artifactId>jaeger-zipkin</artifactId>
    </dependency>

build.gradle

    implementation("io.jaegertracing:jaeger-zipkin")

It contains the dependencies to convert the request to zipkin format. The zipkin compatibility mode will be activated after defining the config property as follows:

    # Enable zipkin compatibility mode
    quarkus.jaeger.zipkin.compatibility-mode=true

## Jaeger Configuration Reference

Configuration property fixed at build time - All other configuration properties are overridable at runtime

Configuration property | Type | Default
--- | --- | ---
`quarkus.jaeger.enabled` Defines if the Jaeger extension is enabled. Environment variable: `QUARKUS_JAEGER_ENABLED` | boolean | `true`
`quarkus.jaeger.metrics.enabled` Whether metrics are published in case a metrics extension is present. Environment variable: `QUARKUS_JAEGER_METRICS_ENABLED` | boolean | `false`
`quarkus.jaeger.endpoint` The traces endpoint, in case the client should connect directly to the Collector, like http://jaeger-collector:14268/api/traces Environment variable: `QUARKUS_JAEGER_ENDPOINT` | URI |
`quarkus.jaeger.auth-token` Authentication Token to send as "Bearer" to the endpoint Environment variable: `QUARKUS_JAEGER_AUTH_TOKEN` | string |
`quarkus.jaeger.user` Username to send as part of "Basic" authentication to the endpoint Environment variable: `QUARKUS_JAEGER_USER` | string |
`quarkus.jaeger.password` Password to send as part of "Basic" authentication to the endpoint Environment variable: `QUARKUS_JAEGER_PASSWORD` | string |
`quarkus.jaeger.agent-host-port` The hostname and port for communicating with agent via UDP Environment variable: `QUARKUS_JAEGER_AGENT_HOST_PORT` | host:port |
`quarkus.jaeger.reporter-log-spans` Whether the reporter should also log the spans Environment variable: `QUARKUS_JAEGER_REPORTER_LOG_SPANS` | boolean |
`quarkus.jaeger.reporter-max-queue-size` The reporter’s maximum queue size Environment variable: `QUARKUS_JAEGER_REPORTER_MAX_QUEUE_SIZE` | int |
`quarkus.jaeger.reporter-flush-interval` The reporter’s flush interval Environment variable: `QUARKUS_JAEGER_REPORTER_FLUSH_INTERVAL` | Duration |
`quarkus.jaeger.sampler-type` The sampler type (const, probabilistic, ratelimiting or remote) Environment variable: `QUARKUS_JAEGER_SAMPLER_TYPE` | string |
`quarkus.jaeger.sampler-param` The sampler parameter (number) Environment variable: `QUARKUS_JAEGER_SAMPLER_PARAM` | BigDecimal |
`quarkus.jaeger.sampler-manager-host-port` The host name and port when using the remote controlled sampler Environment variable: `QUARKUS_JAEGER_SAMPLER_MANAGER_HOST_PORT` | host:port |
`quarkus.jaeger.service-name` The service name Environment variable: `QUARKUS_JAEGER_SERVICE_NAME` | string |
`quarkus.jaeger.tags` A comma separated list of name = value tracer level tags, which get added to all reported spans. The value can also refer to an environment variable using the format ${envVarName:default}, where the :default is optional, and identifies a value to be used if the environment variable cannot be found Environment variable: `QUARKUS_JAEGER_TAGS` | string |
`quarkus.jaeger.propagation` Comma separated list of formats to use for propagating the trace context. Defaults to the standard Jaeger format. Valid values are jaeger and b3 Environment variable: `QUARKUS_JAEGER_PROPAGATION` | string |
`quarkus.jaeger.sender-factory` The sender factory class name Environment variable: `QUARKUS_JAEGER_SENDER_FACTORY` | string |
`quarkus.jaeger.log-trace-context` Whether the trace context should be logged. Environment variable: `QUARKUS_JAEGER_LOG_TRACE_CONTEXT` | boolean | `true`
`quarkus.jaeger.disable-tracer-registration` Whether the registration of tracer as the global tracer should be disabled. This setting should only be turned on in tests that need to install a mock tracer. Environment variable: `QUARKUS_JAEGER_DISABLE_TRACER_REGISTRATION` | boolean | `false`
`quarkus.jaeger.zipkin.compatibility-mode` Whether jaeger should run in zipkin compatibility mode Environment variable: `QUARKUS_JAEGER_ZIPKIN_COMPATIBILITY_MODE` | boolean | `false`

| About the Duration format The format for durations uses the standard `java.time.Duration` format. You can learn more about it in the Duration#parse() javadoc. You can also provide duration values starting with a number. In this case, if the value consists only of a number, the converter treats the value as seconds. Otherwise, `PT` is implicitly prepended to the value to obtain a standard `java.time.Duration` format.