Fully initialize OpenTelemetry items during start-up

microprofile/telemetry/src/main/java/io/helidon/microprofile/telemetry/TelemetryCdiExtension.java

@@ -15,13 +15,19 @@
  */
 package io.helidon.microprofile.telemetry;
 
+import io.helidon.tracing.Tracer;
+
 import io.opentelemetry.instrumentation.annotations.WithSpan;
+import jakarta.annotation.Priority;
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.enterprise.context.Initialized;
 import jakarta.enterprise.event.Observes;
 import jakarta.enterprise.inject.spi.BeforeBeanDiscovery;
 import jakarta.enterprise.inject.spi.Extension;
 import jakarta.enterprise.inject.spi.ProcessAnnotatedType;
 import jakarta.enterprise.inject.spi.WithAnnotations;
 import jakarta.enterprise.inject.spi.configurator.AnnotatedMethodConfigurator;
+import jakarta.interceptor.Interceptor;
 
 /**
  * CDI extension for Microprofile Telemetry implementation.
@@ -62,4 +68,13 @@ void processAnnotations(@Observes @WithAnnotations(WithSpan.class) ProcessAnnota
             }
         }
     }
+
+    void finish(@Observes @Priority(Interceptor.Priority.LIBRARY_BEFORE) @Initialized(ApplicationScoped.class) Object startup,
+                Tracer tracer) {
+        // Forcing CDI to get us a tracer and then invoking one of the bean's methods triggers the producer to do its
+        // initialization, including setting the global tracer as part of start up.
+        tracer.enabled();
+        LOGGER.log(System.Logger.Level.TRACE,
+                   () -> "Global tracer set to " + tracer.unwrap(io.opentelemetry.api.trace.Tracer.class));
+    }
 }

microprofile/telemetry/src/test/java/io/helidon/microprofile/telemetry/TestExtension.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.helidon.microprofile.telemetry;
+
+import io.helidon.tracing.Tracer;
+
+import jakarta.enterprise.context.ApplicationScoped;
+import jakarta.enterprise.context.Initialized;
+import jakarta.enterprise.event.Observes;
+import jakarta.enterprise.inject.spi.Extension;
+
+public class TestExtension implements Extension {
+
+    static Tracer globalTracerAtStartup;
+
+    void startup(@Observes @Initialized(ApplicationScoped.class) Object startup) {
+        globalTracerAtStartup = Tracer.global();
+    }
+}

microprofile/telemetry/src/test/java/io/helidon/microprofile/telemetry/TestTracerAtStartup.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.helidon.microprofile.telemetry;
+
+import io.helidon.microprofile.testing.junit5.AddConfig;
+import io.helidon.microprofile.testing.junit5.HelidonTest;
+
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.not;
+
+@HelidonTest
+@AddConfig(key = "otel.sdk.disabled", value = "false")
+class TestTracerAtStartup {
+
+    @Test
+    void checkForFullFeaturedTracerAtStartup() {
+        assertThat("Global tracer from start-up extension",
+                   TestExtension.globalTracerAtStartup.unwrap(io.opentelemetry.api.trace.Tracer.class).getClass().getName(),
+                   not(containsString("Default")));
+    }
+}

microprofile/telemetry/src/test/resources/META-INF/services/jakarta.enterprise.inject.spi.Extension

@@ -0,0 +1 @@
+io.helidon.microprofile.telemetry.TestExtension