RxJava instrumentation not working via auto configuration

[akashsolanki]

RxJava app does not send any trace to Jaeger automatically. It only works using a manual Tracer Configuration and wrapping the subscribers and observers in the Tracer decorators (like in this app).

Please see this stackoverflow question for details.

Is this expected? Shouldn't it work automatically without having to configure a Tracer bean?

Below is my pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example.springcloud</groupId>
    <artifactId>rxjava</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>rxjava</name>
    <description>RxJava Spring Cloud</description>

    <properties>
        <java.version>11</java.version>
        <spring-cloud.version>Hoxton.SR6</spring-cloud.version>
    </properties>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>io.opentracing.contrib</groupId>
            <artifactId>opentracing-spring-jaeger-cloud-starter</artifactId>
            <version>3.2.0</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
            <version>2.3.4.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>io.reactivex</groupId>
            <artifactId>rxjava</artifactId>
            <version>1.3.8</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

[julianocosta89]

Just adding a little bit of context here, all the other Spring Cloud instrumentation samples didn't require to instrument anything. All is done automatically, that's why I was expecting the same behavior for RxJava.

Instrumenting all the Rx objects and adding @Bean works, but that's a manual task and it's different from all the other cases.