Logico_jp explains how developers can enable zero-code instrumentation with Micronaut applications to automatically send telemetry (traces and metrics) to Azure Monitor. This guide walks through concrete steps, from setup to testing, offering practical insights for Java and Micronaut practitioners working with Azure.

Zero-Code Instrumentation: Sending Micronaut App Signals to Azure Monitor

Author: Logico_jp

Posted August 13, 2025

This guide shows how to configure a Micronaut REST API backend to automatically send traces and metrics to Azure Monitor (Application Insights) using zero-code instrumentation—no manual tracing code needed. The approach covers both JVM and GraalVM native image deployments.

Background & Prerequisites

This solution uses Micronaut (v4.9.0+), Java 21, Maven 3.9.10, Azure Monitor (Application Insights), and PostgreSQL Flexible Server.
The application is a REST API for managing movie data, using PostgreSQL for persistence.

Original Japanese post
Send signals from Micronaut native image applications to Azure Monitor
Micronaut Launch
[Zero-code OpenTelemetry](https://opentelemetry.io/docs/concepts/instrumentation/zero-code/)

Application Setup Overview

1. Project Archetype and Features

You can bootstrap your application using either the Micronaut CLI (mn) or Micronaut Launch. Choose the following features:

graalvm, management, micrometer-azure-monitor, azure-tracing, yaml, validation, postgres, jdbc-hikari, data-jpa

2. Key Dependencies

To instrument HTTP and JDBC tracing with OpenTelemetry:

<dependency>
  <groupId>io.micronaut.tracing</groupId>
  <artifactId>micronaut-tracing-opentelemetry-http</artifactId>
</dependency>
<dependency>
  <groupId>io.micronaut.tracing</groupId>
  <artifactId>micronaut-tracing-opentelemetry-jdbc</artifactId>
</dependency>

For native image compatibility:

<dependency>
  <groupId>org.graalvm.buildtools</groupId>
  <artifactId>graalvm-reachability-metadata</artifactId>
  <version>0.11.0</version>
</dependency>

Add the GraalVM Maven plugin for native image configuration and optimization.

3. Environment Configuration

Configuration relies on application.yml for:

Database credentials (JDBC_URL, JDBC_USERNAME, JDBC_PASSWORD)
Azure Monitor Application Insights connection string (AZURE_MONITOR_CONNECTION_STRING)

Separate metric and trace configuration locations are needed—recommended via environment variables.

Sample snippet:

micronaut:
  application:
    name: micronaut-telemetry-movie
  metrics:
    enabled: true
    export:
      azuremonitor:
        enabled: true
        step: PT1M
        connectionString: ${AZURE_MONITOR_CONNECTION_STRING}
datasources:
  default:
    driver-class-name: org.postgresql.Driver
    db-type: postgres
    url: ${JDBC_URL}
    username: ${JDBC_USERNAME}
    password: ${JDBC_PASSWORD}

azure:
  tracing:
    connection-string: ${AZURE_MONITOR_CONNECTION_STRING}

4. Native Image Configuration

Native image builds require generated metadata and plugin options:

Run app with native-image agent to collect config and trace files.
Create configuration files (reflect-config.json, resource-config.json, etc.) and place them in src/main/resources/META-INF/native-image/{groupId}/{artifactId}.
Set up native-image.properties to define initialization timing and CLI options (-Ob for quicker builds).

Build the image with Maven:

mvn package -Dpackaging=native-image

Testing and Observability

Run as Java, then Native Image: Confirm that traces and metrics are sent to Application Insights.
Populate test data:

curl -X PUT https://<app-url>/api/movies

# Should respond: { "message":"Database initialized with default movies." }

Verify data and metrics:

curl https://<app-url>/api/movies
curl https://<app-url>/metrics

JVM-specific metrics (e.g., jvm.memory.max) may not be available or return placeholder values (e.g., -2) in native images.

Logs to Traces Table Limitation:
- Zero-code cannot currently send application logs to Azure Monitor ‘traces’. Manual OpenTelemetry SDK configuration is required (custom Appender injection in controller constructor).

Code Example

GitHub: anishi1222/micronaut-telemetry-movie

Key Takeaways

Zero-code instrumentation using Micronaut and OpenTelemetry simplifies exporting traces and metrics to Azure Monitor—no manual code required.
Native images demand special configuration for accurate monitoring.
Application logs require explicit OpenTelemetry SDK use for integration into Azure Monitor ‘traces’.

This post appeared first on “Microsoft Tech Community”. Read the entire article here