Add producers for Otel Span and Baggage

docs/src/main/asciidoc/opentelemetry.adoc

@@ -423,6 +423,38 @@ class SpanBean {
 }
 ----
 
+=== Available OpenTelemetry CDI injections
+
+As per MicroProfile Telemetry Tracing specification, Quarkus supports the CDI injections of the
+following classes:
+
+* `io.opentelemetry.api.OpenTelemetry`
+* `io.opentelemetry.api.trace.Tracer`
+* `io.opentelemetry.api.trace.Span`
+* `io.opentelemetry.api.baggage.Baggage`
+
+You can inject these classes in any CDI enabled bean. For instance, the `Tracer` is particularly useful to start custom spans:
+
+[source,java]
+----
+@Inject
+Tracer tracer;
+
+...
+
+public void tracedWork() {
+    Span span = tracer.spanBuilder("My custom span")
+        .setAttribute("attr", "attr.value")
+        .setParent(Context.current().with(Span.current()))
+        .setSpanKind(SpanKind.INTERNAL)
+        .startSpan();
+
+    // traced work
+
+    span.end();
+}
+----
+
 === SmallRye Reactive Messaging - Kafka
 
 When using the SmallRye Reactive Messaging extension for Kafka,

extensions/opentelemetry/runtime/src/main/java/io/quarkus/opentelemetry/runtime/tracing/cdi/TracerProducer.java

@@ -2,10 +2,13 @@
 
 import static io.quarkus.opentelemetry.runtime.config.OpenTelemetryConfig.INSTRUMENTATION_NAME;
 
+import javax.enterprise.context.RequestScoped;
 import javax.enterprise.inject.Produces;
 import javax.inject.Singleton;
 
 import io.opentelemetry.api.GlobalOpenTelemetry;
+import io.opentelemetry.api.baggage.Baggage;
+import io.opentelemetry.api.trace.Span;
 import io.opentelemetry.api.trace.Tracer;
 import io.quarkus.arc.DefaultBean;
 import io.quarkus.opentelemetry.runtime.tracing.DelayedAttributes;
@@ -31,4 +34,18 @@ public LateBoundSampler getLateBoundSampler() {
     public Tracer getTracer() {
         return GlobalOpenTelemetry.getTracer(INSTRUMENTATION_NAME);
     }
+
+    @Produces
+    @RequestScoped
+    @DefaultBean
+    public Span getSpan() {
+        return Span.current();
+    }
+
+    @Produces
+    @RequestScoped
+    @DefaultBean
+    public Baggage getBaggage() {
+        return Baggage.current();
+    }
 }

integration-tests/opentelemetry/src/test/java/io/quarkus/it/opentelemetry/OpenTelemetryInjectionsTest.java

@@ -0,0 +1,47 @@
+package io.quarkus.it.opentelemetry;
+
+import static io.restassured.RestAssured.get;
+import static io.restassured.RestAssured.given;
+import static java.net.HttpURLConnection.HTTP_OK;
+import static java.util.concurrent.TimeUnit.SECONDS;
+import static org.awaitility.Awaitility.await;
+
+import java.util.List;
+import java.util.Map;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Test;
+
+import io.quarkus.test.junit.QuarkusTest;
+import io.restassured.common.mapper.TypeRef;
+
+@QuarkusTest
+public class OpenTelemetryInjectionsTest {
+
+    @AfterEach
+    void reset() {
+        given().get("/reset").then().statusCode(HTTP_OK);
+        await().atMost(5, SECONDS).until(() -> getSpans().size() == 0);
+    }
+
+    private List<Map<String, Object>> getSpans() {
+        return get("/export").body().as(new TypeRef<>() {
+        });
+    }
+
+    @Test
+    public void testOTelInjections() {
+        given()
+                .when().get("/otel/injection")
+                .then()
+                .statusCode(200);
+    }
+
+    @Test
+    public void testOTelInjectionsAsync() {
+        given()
+                .when().get("/otel/injection/async")
+                .then()
+                .statusCode(200);
+    }
+}

integration-tests/opentelemetry/src/test/java/io/quarkus/it/opentelemetry/util/InjectionResource.java

@@ -0,0 +1,58 @@
+package io.quarkus.it.opentelemetry.util;
+
+import javax.enterprise.context.RequestScoped;
+import javax.inject.Inject;
+import javax.ws.rs.GET;
+import javax.ws.rs.Path;
+import javax.ws.rs.core.Response;
+
+import org.junit.jupiter.api.Assertions;
+
+import io.opentelemetry.api.GlobalOpenTelemetry;
+import io.opentelemetry.api.OpenTelemetry;
+import io.opentelemetry.api.baggage.Baggage;
+import io.opentelemetry.api.trace.Span;
+import io.opentelemetry.api.trace.Tracer;
+import io.smallrye.mutiny.Uni;
+
+@Path("/otel/injection")
+@RequestScoped
+public class InjectionResource {
+
+    @Inject
+    OpenTelemetry openTelemetry;
+
+    @Inject
+    Tracer tracer;
+
+    @Inject
+    Span span;
+
+    @Inject
+    Baggage baggage;
+
+    @GET
+    public Response verifyOTelInjections() {
+        verifyInjections();
+        return Response.ok().build();
+    }
+
+    @GET
+    @Path("/async")
+    public Uni<Response> verifyOTelInjectionsAsync() {
+        verifyInjections();
+        return Uni.createFrom().item(Response.ok().build());
+    }
+
+    private void verifyInjections() {
+        Assertions.assertNotNull(openTelemetry, "OpenTelemetry cannot be injected");
+        Assertions.assertNotNull(tracer, "Tracer cannot be injected");
+        Assertions.assertNotNull(span, "Span cannot be injected");
+        Assertions.assertNotNull(openTelemetry, "Baggage cannot be injected");
+
+        Assertions.assertEquals(GlobalOpenTelemetry.get(), openTelemetry);
+        Assertions.assertEquals(Span.current().getSpanContext(), span.getSpanContext());
+        Assertions.assertEquals(Baggage.current().size(), baggage.size());
+        baggage.asMap().forEach((s, baggageEntry) -> Assertions.assertEquals(baggageEntry, baggage.asMap().get(s)));
+    }
+}