Logico_jp presents a practical tutorial on integrating Micronaut (Java) applications—including native images—with Azure Monitor, explaining every step needed to send traces to Application Insights.

Sending Traces from Micronaut Native Image Applications to Azure Monitor

Author: Logico_jp

Overview

This post demonstrates how to enable the collection and transmission of trace telemetry from Java Micronaut applications (including native images) to Azure Monitor’s Application Insights, using current tools and Microsoft’s recommended approach.

Prerequisites

Maven 3.9.10 or newer
JDK 21
Micronaut 4.9.0+
For native image builds: GraalVM, Graal Dev Kit (GDK)

Reference Links

Project Setup

You can generate a project using either the Micronaut CLI or Micronaut Launch:

With CLI

mn create-app \
  --build=maven \
  --jdk=21 \
  --lang=java \
  --test=junit \
  --features=tracing-opentelemetry-http,validation,graalvm,azure-tracing,http-client,yaml \
  dev.logicojp.micronaut.azuremonitor-metric

Note: Select features: tracing-opentelemetry-http, validation, graalvm, azure-tracing, http-client, and yaml.

Configuration can use application.yml instead of .properties for better structure.

Dependency Management

Add these dependencies in your pom.xml:

<dependency>
  <groupId>io.micronaut.tracing</groupId>
  <artifactId>micronaut-tracing-opentelemetry-http</artifactId>
  <scope>compile</scope>
</dependency>
<dependency>
  <groupId>io.micronaut.azure</groupId>
  <artifactId>micronaut-azure-tracing</artifactId>
</dependency>
<dependency>
  <groupId>com.azure</groupId>
  <artifactId>azure-monitor-opentelemetry-autoconfigure</artifactId>
</dependency>
<dependency>
  <groupId>org.graalvm.buildtools</groupId>
  <artifactId>graalvm-reachability-metadata</artifactId>
  <version>0.11.0</version>
</dependency>

Plugin for Native Images

For GraalVM native image support, add:

<plugin>
  <groupId>org.graalvm.buildtools</groupId>
  <artifactId>native-maven-plugin</artifactId>
  <configuration>
    <metadataRepository>
      <enabled>true</enabled>
    </metadataRepository>
    <buildArgs combine.children="append">
      <buildArg>-Ob</buildArg>
    </buildArgs>
    <quickBuild>true</quickBuild>
  </configuration>
</plugin>

Application Configuration

Specify the Application Insights connection string in application.yml:

azure:
  tracing:
    connection-string: InstrumentationKey=...

Or via environment variable:

azure.tracing.connection-string="InstrumentationKey=..."

Version Conflicts

To avoid Netty or Jackson version conflicts when building native images, consider switching to alternatives such as Undertow or JSON-P/BSON.

Building and Testing

Standard JAR
- mvn clean package
Native Image
- mvn package -Dpackaging=native-image
- Use GraalVM tracing agent to generate configuration files like reflect-config.json, resource-config.json, etc.

Validating Trace Transmission

Run your application and confirm traces appear in Azure Monitor > Application Insights > Application Map.
Use curl to exercise endpoints and observe changes in the map and trace explorer.

Key Points

Always match dependencies and plugins as demonstrated to ensure seamless tracing.
For non-standard configurations or troubleshooting, validate settings between micronaut-azure-tracing and micrometer-azure-monitor.
Native images require additional metadata and configuration steps, especially for reflection and dependency management.