How I can safely check if file exists in S3 bucket using go in lambda?

Question

I am working on a service for my project that is used to synchronize Lambdas works in AWS. The idea is to write a TrackerFile module that will store structures on S3. Each time I use the tracker, I will check if there is a file with the name assigned to the called tracker.

I have no idea but how to safely check if a file with a given name exists on S3. can you show a sample piece of code that would be able to return (bool, err) where bool is True if the file exists?

Answer 1

To ensure compatibility across AWS SDK v3 and AWS SDK v2 I would recommend using both the 404 and the "NotFound" code.

export async function fileExistsInS3(bucket, key) {
    try {
        await s3.send(new HeadObjectCommand({ Bucket: bucket, Key: key }));
        return { fileExists: true };
    } catch (error) {
        if (error.code === 'NotFound' || (error['$fault'] === 'client' && error['$metadata']?.httpStatusCode === 404)) {
            return { fileExists: false };
        }
        throw error; 
    }
}

EDIT: here is the Go version, as requested by Md. A. Apu.

func fileExistsInS3(client *s3.Client, bucket, key string) (bool, error) {
    _, err := client.HeadObject(context.TODO(), &s3.HeadObjectInput{
        Bucket: aws.String(bucket),
        Key:    aws.String(key),
    })
    if err != nil {
        var responseError *awshttp.ResponseError
        if errors.As(err, &responseError) && responseError.ResponseError.HTTPStatusCode() == http.StatusNotFound {
            return false, nil
        }
        return false, err
    }
    return true, nil
}