linnykoleh/lambda-demo

Image Converter

Create Lambda function that will convert JPEG to BMP, GIF, PNG.

Add IAM role to Lambda function to full access S3 bucket

Code for converting image

public class ImageConverterLambda {

    private final AmazonS3 s3Client = AmazonS3ClientBuilder.defaultClient();

    public void handleRequest(S3Event s3Event, Context context) {
        System.out.println("Received event: " + s3Event);
        s3Event.getRecords().forEach(record -> {
            var bucketName = record.getS3().getBucket().getName();
            var key = record.getS3().getObject().getKey();
            try {
                var image = ImageIO.read(s3Client.getObject(bucketName, key).getObjectContent());

                uploadConvertedImage(bucketName, image, "bmp", "bmp/");
                uploadConvertedImage(bucketName, image, "gif", "gif/");
                uploadConvertedImage(bucketName, image, "png", "png/");

            } catch (IOException e) {
                context.getLogger().log("Error processing image: " + e.getMessage());
            }
        });
    }

    private void uploadConvertedImage(String bucketName, BufferedImage image, String format, String folder) throws IOException {
        var outputStream = new ByteArrayOutputStream();
        ImageIO.write(image, format, outputStream);
        var imageBytes = outputStream.toByteArray();

        var inputStream = new ByteArrayInputStream(imageBytes);
        var metadata = new ObjectMetadata();
        metadata.setContentLength(imageBytes.length);
        metadata.setContentType("image/" + format);

        var outputKey = folder + "converted_image." + format;
        var putRequest = new PutObjectRequest(bucketName, outputKey, inputStream, metadata);
        s3Client.putObject(putRequest);
    }
}

Create S3 bucket and upload image

Create Lambda function and add trigger from S3 bucket

Upload java code to Lambda function

Handler has to be the same as the class name and method name demo.lambdademo.ImageConverterLambda::handleRequest as ImageConverterLambda.java

After uploading image to S3 bucket, need to see three folders with converted images

Logs from Lambda function