How to Configure Amazon S3 in Struts

August 20, 2025

Struts is a solid Java web framework, and adding Amazon S3 lets you handle file uploads, downloads, and storage effortlessly. Whether you're testing locally or go live, this guide walks you through integrating S3 into Struts. We’ll use LocalStack for local Docker development and real AWS S3 credentials for production with Kubernetes—keeping configurations clean, secure, and environment-specific.

1. Add the Right Dependencies to `pom.xml`

<dependencies>>  <!-- Struts framework -->
  <dependency>
    <groupId>org.apache.struts</groupId>
    <artifactId>struts2-core</artifactId>
    <version>${struts.version}</version>
  </dependency>

  <!-- AWS SDK for S3 -->
  <dependency>
    <groupId>software.amazon.awssdk</groupId>
    <artifactId>s3</artifactId>
    <version>${aws.sdk.version}</version>
  </dependency>

  <!-- Kubernetes client for production config -->
  <dependency>
    <groupId>io.fabric8</groupId>
    <artifactId>kubernetes-client</artifactId>
    <version>${fabric8.version}</version>
  </dependency>
</dependencies>

You get Struts for the web layer, AWS SDK for S3 access, and Kubernetes client support for managing deployments.

2. Run LocalStack via Docker for Development

LocalStack acts like fake AWS, ideal for local testing:

version: '3'
services:
  localstack:
    image: localstack/localstack:s3-latest
    environment:
      - SERVICES=s3
      - AWS_ACCESS_KEY_ID=test
      - AWS_SECRET_ACCESS_KEY=test
    ports:
      - "4566:4566"
    volumes:
      - "./init-s3.sh:/etc/localstack/init/ready.d/init-s3.sh"

Create init-s3.sh to initialize a test bucket:

#!/usr/bin/env bash
awslocal s3api create-bucket --bucket struts-dev-bucket

Start it:

docker-compose up -d

You now have a local S3-compatible endpoint at http://localhost:4566 with your bucket ready

3. Development Configuration: `s3-dev.properties`

Create this file in src/main/resources:

s3.endpoint=http://localhost:4566
s3.region=us-east-1
s3.bucket=struts-dev-bucket
s3.accessKey=test
s3.secretKey=test

Use it in Java like this:

AwsBasicCredentials creds = AwsBasicCredentials.create(
    props.getProperty("s3.accessKey"),
    props.getProperty("s3.secretKey")
);
S3Client client = S3Client.builder()
    .endpointOverride(URI.create(props.getProperty("s3.endpoint")))
    .region(Region.of(props.getProperty("s3.region")))
    .credentialsProvider(StaticCredentialsProvider.create(creds))
    .forcePathStyle(true)
    .build();

The .forcePathStyle(true) is important for LocalStack path-style addressing.

4. Prepare AWS S3 Configuration for Production

Store real S3 settings in Kubernetes:

kubectl create secret generic aws-secret \
  --from-literal=AWS_ACCESS_KEY_ID=yourKey \
  --from-literal=AWS_SECRET_ACCESS_KEY=yourSecret

kubectl create configmap aws-config \
  --from-literal=S3_BUCKET=struts-prod-bucket \
  --from-literal=S3_REGION=us-east-1

5. Production Configuration: `s3-prod.properties`

Include this in your resources:

s3.endpoint=https://s3.${S3_REGION}.amazonaws.com
s3.region=${S3_REGION}
s3.bucket=${S3_BUCKET}
s3.accessKey=${AWS_ACCESS_KEY_ID}
s3.secretKey=${AWS_SECRET_ACCESS_KEY}

No code changes required—just environment variables differ.

6. Kubernetes Deployment Snippet

Add to your Deployment spec:

env:
  - name: AWS_ACCESS_KEY_ID
    valueFrom:
      secretKeyRef:
        name: aws-secret
        key: AWS_ACCESS_KEY_ID
  - name: AWS_SECRET_ACCESS_KEY
    valueFrom:
      secretKeyRef:
        name: aws-secret
        key: AWS_SECRET_ACCESS_KEY
  - name: S3_BUCKET
    valueFrom:
      configMapKeyRef:
        name: aws-config
        key: S3_BUCKET
  - name: S3_REGION
    valueFrom:
      configMapKeyRef:
        name: aws-config
        key: S3_REGION

Struts app will automatically pick up AWS credentials and bucket info.

7. Example Code for Upload in Struts Action

public class S3Action extends ActionSupport {
  public String execute() {
    Properties p = loadProps("s3-" + (System.getenv("S3_BUCKET")!=null ? "prod" : "dev") + ".properties");
    S3Client s3 = buildClient(p);
    s3.putObject(PutObjectRequest.builder()
        .bucket(p.getProperty("s3.bucket"))
        .key("example.txt")
        .build(),
      RequestBody.fromString("Hello from Struts!"));

    addActionMessage("Uploaded to S3 bucket " + p.getProperty("s3.bucket"));
    return SUCCESS;
  }
}

Same code works in development and production.

1. Add the Right Dependencies to pom.xml