> For the complete documentation index, see [llms.txt](https://docs.poja.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.poja.io/examples/hello-world-with-s3-file-storage.md).
# Hello World with S3 file Storage
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### Goal
We want **to add persistence using an S3 Bucket** to an [**Hello World Application**](https://poja.gitbook.io/poja-docs/examples/hello-world-but-straight-to-the-cloud) already hosted on Poja that exposes the `/hello?name=your-name` endpoint, for which it :
* Writes a Hello World message inside a *.txt* file
* Uploads the file to an S3 bucket
* Returns a **presigned uri** to download the file
{% hint style="info" %}
Deploy in one click
Before diving into the step-by-step guide, you can simply click the **Deploy to Poja** button. This will instantly deploy [**this template**](https://github.com/poja-app/poja-fs-template) to your Poja account
Deploy to Poja
{% endhint %}
### How-to in 2 steps
#### **Step 1: Enable file storage for the preprod environment**
Select the **preprod environment**, click on the **Edit** button on the **Poja Configuration** section and then:
* Enable the **File Storage**
* Click on the **Save** button
Once it’s done, wait for the deployment to finish.
{% hint style="info" %}
/health/bucket
Once the **File Storage** option is activated, `/health/bucket` endpoint will be added to the application. It returns a presigned URI which gives you read-only access to tiny files created in the bucket for testing purpose.
{% endhint %}
#### Step 2: Code your endpoint
{% hint style="info" %}
The BucketComponent class
To interact with the S3 Bucket associated to your application, Poja provides the **BucketComponent** class which has **4 public methods:**
* `upload()`
* `download()` to download a specific file by specifying its name
* `presign()` to get a **presigned uri** to access a specific file for a specified duration
* `getBucketName()`
{% endhint %}
{% code title="Java" %}
```java
package com.my.company.service;
import static java.io.File.createTempFile;
import com.my.company.file.bucket.BucketComponent;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.time.Duration;
import lombok.AllArgsConstructor;
import lombok.SneakyThrows;
import org.springframework.stereotype.Service;
@Service
@AllArgsConstructor
public class HelloWorldService {
private final BucketComponent bucketComponent;
@SneakyThrows
public String uploadHelloWorldMessage(String name) {
var fileSuffix = ".txt";
var filePrefix = "hello-world-" + name;
var bucketKey = filePrefix + fileSuffix;
var fileToUpload = createTempFile(filePrefix, fileSuffix);
writeMessageIntoFile("Hello World " + name + " !", fileToUpload);
bucketComponent.upload(fileToUpload, bucketKey);
return bucketComponent.presign(bucketKey, Duration.ofMinutes(5)).toString();
}
private void writeMessageIntoFile(String message, File file) throws IOException {
FileWriter writer = new FileWriter(file);
writer.write(message);
writer.close();
}
}
```
{% endcode %}
{% code title="Java" %}
```java
package com.my.company.endpoint.rest.controller;
import com.my.company.service.HelloWorldService;
import lombok.AllArgsConstructor;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@RestController
@AllArgsConstructor
public class HelloWorldController {
private final HelloWorldService service;
@GetMapping("/hello")
public String helloWorld(@RequestParam String name) {
return service.uploadHelloWorldMessage(name);
}
}
```
{% endcode %}
To trigger a deployment, just **commit and push** the code to the **preprod branch** of the repository. Wait. And voilà!
***