AWS S3에 파일 올리기 (Presigned URL)

1. AWS SDK 의존성 추가

<dependency>
	<groupId>software.amazon.awssdk</groupId>
	<artifactId>s3</artifactId>
	<version>2.20.125</version>
</dependency>

 

2. application.yml 추가

aws:
    s3:
        bucket-name: {bucketName}
        endpoint: {endPoint}

 

3. 컨트롤러

 @GetMapping("/generate-presigned-url")
    public String generatePresignedUrl(@RequestParam String fileName) {
        URL url = s3Service.generatePresignedUrl(fileName);
        return url.toString();
    }

 

4. 서비스 코드

@Service
public class S3Service {

	@Autowired
	private S3Presigner s3presigner;

    @Value("${aws.s3.bucket-name}")
    private String s3_bucket_name;
    
    @Value("${aws.s3.endpoint}")
    private String s3_endpoint;


    public URL generatePresignedUrl(String objectKey) {
        PutObjectRequest putObjectRequest = PutObjectRequest.builder()
                .bucket(bucketName)
                .key(objectKey)
                .build();

        PutObjectPresignRequest presignRequest = PutObjectPresignRequest.builder()
                .signatureDuration(Duration.ofMinutes(10)) // URL 유효시간 설정
                .putObjectRequest(putObjectRequest)
                .build();

        return s3Presigner.presignPutObject(presignRequest).url();
    }
}

 

 

이렇게해서 생성된 url에 PUT으로 파일을 올려주면 성공

 

 

+) accesskey를 세팅하지 않아도 되는 이유

S3Presigner 라이브러리를 사용 중인데, 내부를 살펴보면 credential을 DefaultCredentialsProvider에서 가져온다는 것을 알 수 있다.

DefaultCredentialsProvider는 알아서 키를 세팅하는데 방법은 아래와 같다

 

1. Java System Properties - aws.accessKeyId and aws.secretAccessKey
2. Environment Variables - AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY
3. Web Identity Token credentials from system properties or environment variables
4. Credential profiles file at the default location (~/.aws/credentials) shared by all AWS SDKs and the AWS CLI
5. Credentials delivered through the Amazon EC2 container service if AWS_CONTAINER_CREDENTIALS_RELATIVE_URI" environment variable is set and security manager has permission to access the variable,
6. Instance profile credentials delivered through the Amazon EC2 metadata service

 

 

reference

S3Presigner (AWS SDK for Java - 2.26.15)

S3Presigner (AWS SDK for Java - 2.27.4)

DefaultCredentialsProvider (AWS SDK for Java - 2.26.15)