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Integrating MinIO with Micronaut can be a great way to add reliable object storage to your application—especially since MinIO is lightweight, self-hosted, and fully S3-compatible. Whether you're working locally with Docker or deploying to Kubernetes, Micronaut makes it easy to manage different configurations using profile-specific application.properties files.
In this article, you'll learn how to set up MinIO in a Micronaut application using application-dev.properties for development and application-prod.properties for production, with Docker and Kubernetes as the respective environments.

Step 1: Add Required Dependencies

Start by updating your pom.xml with the required libraries: 
<dependencies>
  <!-- MinIO via AWS-compatible object storage -->
  <dependency>
    <groupId>io.micronaut.objectstorage</groupId>
    <artifactId>micronaut-object-storage-aws</artifactId>
  </dependency>

  <!-- Micronaut runtime -->
  <dependency>
    <groupId>io.micronaut</groupId>
    <artifactId>micronaut-runtime</artifactId>
  </dependency>

  <!-- Kubernetes client support -->
  <dependency>
    <groupId>io.micronaut.kubernetes</groupId>
    <artifactId>micronaut-kubernetes-client</artifactId>
  </dependency>
</dependencies>
These dependencies enable S3-compatible access (which works with MinIO), YAML/Properties configuration, and Kubernetes integration.

Step 2: Spin Up MinIO Using Docker (for Dev)

To quickly launch MinIO locally for development: 
docker run -p 9000:9000 -p 9001:9001 \
  -e MINIO_ROOT_USER=devuser \
  -e MINIO_ROOT_PASSWORD=devpass123 \
  -v minio-data:/data \
  minio/minio server /data --console-address ":9001"

Step 3: Create application-dev.properties

Set up the development-specific configuration in src/main/resources/application-dev.properties: 
micronaut.application.name=minio-app
micronaut.object-storage.default.provider=aws
micronaut.object-storage.default.region=us-east-1
micronaut.object-storage.default.access-key-id=devuser
micronaut.object-storage.default.secret-access-key=devpass123
micronaut.object-storage.default.endpoint=http://localhost:9000
micronaut.object-storage.default.path-style-access=true
To run your application with this configuration: 
./mvnw mn:run -Dmicronaut.environments=dev
Micronaut will automatically use the dev profile and connect to your local MinIO instance.

Step 4: Configure Production with Kubernetes

In production, you should not hardcode secrets or environment-specific values. Kubernetes makes it easy to manage these settings using ConfigMaps and Secrets.

4.1: Create a Kubernetes ConfigMap

apiVersion: v1
kind: ConfigMap
metadata:
  name: minio-config
data:
  MINIO_ENDPOINT: http://minio-service:9000

4.2: Create a Kubernetes Secret

apiVersion: v1
kind: Secret
metadata:
  name: minio-secret
type: Opaque
data:
  MINIO_ACCESS_KEY: cHJvZHVzZXI=       # 'produser' (base64)
  MINIO_SECRET_KEY: cHJvZHBhc3MxMjM=   # 'prodpass123' (base64)

Step 5: Create application-prod.properties

This file will use environment variables injected by Kubernetes: 
micronaut.application.name=minio-app
micronaut.object-storage.default.provider=aws
micronaut.object-storage.default.region=us-east-1
micronaut.object-storage.default.access-key-id=${MINIO_ACCESS_KEY}
micronaut.object-storage.default.secret-access-key=${MINIO_SECRET_KEY}
micronaut.object-storage.default.endpoint=${MINIO_ENDPOINT}
micronaut.object-storage.default.path-style-access=true

Step 6: Use Environment Variables in Kubernetes Deployment

Update your Micronaut app's Kubernetes deployment to use these values: 
env:
  - name: MICRONAUT_ENVIRONMENTS
    value: prod
  - name: MINIO_ENDPOINT
    valueFrom:
      configMapKeyRef:
        name: minio-config
        key: MINIO_ENDPOINT
  - name: MINIO_ACCESS_KEY
    valueFrom:
      secretKeyRef:
        name: minio-secret
        key: MINIO_ACCESS_KEY
  - name: MINIO_SECRET_KEY
    valueFrom:
      secretKeyRef:
        name: minio-secret
        key: MINIO_SECRET_KEY
This ensures that your application will automatically pull MinIO configuration based on the production profile.

Step 7: Summary

By splitting your configurations into application-dev.properties and application-prod.properties, you create a clear separation between development and production. This makes your Micronaut app safer and easier to maintain.
  • Docker handles your dev environment with hardcoded values in a local instance.
  • Kubernetes handles production, securely injecting variables through Secrets and ConfigMaps.
  • Micronaut’s native support for environment-specific properties simplifies switching between environments.
This setup is perfect for projects that need a fast, scalable, and reliable object storage solution without the overhead of managing AWS S3 directly.

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