How to get region of S3 bucket with Bucket name?

Question

I am working on project with Amazon S3 and I am using AWS SDK 2 to interact with S3. I have many old buckets created into my S3 account and now I want to change the code of authentication and setting the ACL.

I have created S3Client :

AwsBasicCredentials awsCreds = AwsBasicCredentials.create(
                    ACCESS_KEY,
                    SECRET_KEY);
            S3ClientBuilder s3ClientBuilder = S3Client.builder().credentialsProvider(StaticCredentialsProvider.create(awsCreds));
            if (regionString != null) {
                Region region = Region.of(regionString);
                s3ClientBuilder.region(region);
            }           
            S3Client s3Client = s3ClientBuilder.build();
            return s3Client;

Default region I have given is : US_EAST_1.

If I do not specify this region then it showing the creation dates of bucket wrong.

Now by using above S3client, I am moving forward and working with ACL :

software.amazon.awssdk.services.s3.model.GetBucketAclRequest getBucketAclRequest =                        

software.amazon.awssdk.services.s3.model.GetBucketAclRequest.builder().bucket(sbktname).build();
GetBucketAclResponse bucketAcl1 = s3Client.getBucketAcl(getBucketAclRequest);

But it throwing issue : software.amazon.awssdk.services.s3.model.S3Exception: The authorization header is malformed; the region 'us-east-1' is wrong; expecting 'eu-central-1'

My question is that how can I get region from existing s3 client which already created using bucket name only. I do not have bucket object, I have bucket name only.

Using bucket name I tried to get the location but it throwing same issue of region mentioned above.

Answer 1

I can't give you an example in Java, but you need to use GetBucketLocation API.
https://docs.aws.amazon.com/AmazonS3/latest/API/API_GetBucketLocation.html

From the following example look that I am forcing to run the command on sa-east-1 region but my bucket is located on us-east-2.

$ aws --region sa-east-1 s3api get-bucket-location --bucket my-bucket
{
    "LocationConstraint": "us-east-2"
}

You can see the same behavior from Python SDK

Python 3.9.4 (default, Apr  5 2021, 01:49:30)
[Clang 12.0.0 (clang-1200.0.32.29)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import boto3
>>> s3 = boto3.client('s3', region_name='sa-east-1')
>>> s3.get_bucket_location(Bucket='my-bucket')['LocationConstraint']
'us-east-2'

Buckets in Region us-east-1 have a LocationConstraint of null.

Answer 2

My question is that how can I get region from existing s3 client which already created using bucket name only. I do not have bucket object, I have bucket name only.

You can use s3api to get the bucket location e.g. if your bucket name is abc123, you can get the location using the following command:

aws s3api get-bucket-location --bucket abc123

Check the get-bucket-location documentation page to learn more about it.