Enabling tracing with Spring Cloud Sleuth and OpenTelemetry

pom.xml

<properties>
    <spring-cloud.version>2021.0.0-M2</spring-cloud.version>
    <spring-cloud-sleuth-otel.version>1.1.0-M3</spring-cloud-sleuth-otel.version>
    <opentelemetry-exporter-otlp>1.7.0</opentelemetry-exporter-otlp>
    <grpc-netty-shaded>1.41.0</grpc-netty-shaded>
</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>

        <!-- Spring Cloud Sleuth OTel requires a Spring Cloud Sleuth OTel BOM -->
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-sleuth-otel-dependencies</artifactId>
            <version>${spring-cloud-sleuth-otel.version}</version>
            <scope>import</scope>
            <type>pom</type>
        </dependency>
    </dependencies>
</dependencyManagement>

<!-- Sleuth with Brave tracer implementation -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-sleuth</artifactId>
    <exclusions>
        <!-- Exclude Brave (the default) -->
        <exclusion>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-sleuth-brave</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<!-- Add OpenTelemetry tracer -->
<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-sleuth-otel-autoconfigure</artifactId>
</dependency>
<!-- https://mvnrepository.com/artifact/io.opentelemetry/opentelemetry-exporter-otlp -->
<dependency>
    <groupId>io.opentelemetry</groupId>
    <artifactId>opentelemetry-exporter-otlp</artifactId>
    <version>${opentelemetry-exporter-otlp}</version>
</dependency>
<!-- https://mvnrepository.com/artifact/io.grpc/grpc-netty -->
<dependency>
    <groupId>io.grpc</groupId>
    <artifactId>grpc-netty-shaded</artifactId>
    <version>${grpc-netty-shaded}</version>
</dependency>

<repositories>
    <repository>
        <id>spring-snapshots</id>
        <url>https://repo.spring.io/snapshot</url>
        <snapshots>
            <enabled>true</enabled>
        </snapshots>
    </repository>
    <repository>
        <id>spring-milestones</id>
        <url>https://repo.spring.io/milestone</url>
    </repository>
</repositories>
<pluginRepositories>
    <pluginRepository>
        <id>spring-snapshots</id>
        <url>https://repo.spring.io/snapshot</url>
    </pluginRepository>
    <pluginRepository>
        <id>spring-milestones</id>
        <url>https://repo.spring.io/milestone</url>
    </pluginRepository>
</pluginRepositories>

Summary:

1. Include the Spring Cloud and Spring Cloud Sleuth OTEL BOM as dependency management.
2. Remove the default Brave implementation (no vendor locking).
3. Include the OpenTelemetry library.
4. Include the OpenTelemetry exporter to send the traces and spans to a remote instrumentation backend.
5. Include GRPC Netty Shaded (used by exporter) because there is some disagreement within Spring on providing a default GRPC implementation. See spring-projects-experimental/spring-cloud-sleuth-otel#39
6. Since we are using unreleased versions that are not available in Maven Central, we have to include the Spring Snapshots and Milestone repositories.