Use PutBucketPolicy with an AWS SDK

Apply a bucket policy to a directory bucket.

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.s3.S3Client;
import software.amazon.awssdk.services.s3.model.PutBucketPolicyRequest;
import software.amazon.awssdk.services.s3.model.S3Exception;

import static com.example.s3.util.S3DirectoryBucketUtils.createDirectoryBucket;
import static com.example.s3.util.S3DirectoryBucketUtils.createS3Client;
import static com.example.s3.util.S3DirectoryBucketUtils.deleteDirectoryBucket;
import static com.example.s3.util.S3DirectoryBucketUtils.getAwsAccountId;

    /**
     * Sets the following bucket policy for the specified S3 directory bucket.
     *<pre>
     * {
     *     "Version": "2012-10-17",
     *     "Statement": [
     *         {
     *             "Sid": "AdminPolicy",
     *             "Effect": "Allow",
     *             "Principal": {
     *                 "AWS": "arn:aws:iam::<ACCOUNT_ID>:root"
     *             },
     *             "Action": "s3express:*",
     *             "Resource": "arn:aws:s3express:us-west-2:<ACCOUNT_ID>:bucket/<DIR_BUCKET_NAME>
     *         }
     *     ]
     * }
     * </pre>
     * This policy grants all S3 directory bucket actions to identities in the same account as the bucket.
     *
     * @param s3Client   The S3 client used to interact with S3
     * @param bucketName The name of the directory bucket
     * @param policyText The policy text to be applied
     */
    public static void putDirectoryBucketPolicy(S3Client s3Client, String bucketName, String policyText) {
        logger.info("Setting policy on bucket: {}", bucketName);
        logger.info("Policy: {}", policyText);

        try {
            PutBucketPolicyRequest policyReq = PutBucketPolicyRequest.builder()
                    .bucket(bucketName)
                    .policy(policyText)
                    .build();

            s3Client.putBucketPolicy(policyReq);
            logger.info("Bucket policy set successfully!");

        } catch (S3Exception e) {
            logger.error("Failed to set bucket policy: {} - Error code: {}", e.awsErrorDetails().errorMessage(),
                    e.awsErrorDetails().errorCode(), e);
            throw e;
        }
    }