Use PutObjectRetention with an Amazon SDK or CLI

    /// <summary>
    /// Set or modify a retention period on an object in an S3 bucket.
    /// </summary>
    /// <param name="bucketName">The bucket of the object.</param>
    /// <param name="objectKey">The key of the object.</param>
    /// <param name="retention">The retention mode.</param>
    /// <param name="retainUntilDate">The date retention expires.</param>
    /// <returns>True if successful.</returns>
    public async Task<bool> ModifyObjectRetentionPeriod(string bucketName,
        string objectKey, ObjectLockRetentionMode retention, DateTime retainUntilDate)
    {
        try
        {
            var request = new PutObjectRetentionRequest()
            {
                BucketName = bucketName,
                Key = objectKey,
                Retention = new ObjectLockRetention()
                {
                    Mode = retention,
                    RetainUntilDate = retainUntilDate
                }
            };

            var response = await _amazonS3.PutObjectRetentionAsync(request);
            Console.WriteLine($"\tSet retention for {objectKey} in {bucketName} until {retainUntilDate:d}.");
            return response.HttpStatusCode == System.Net.HttpStatusCode.OK;
        }
        catch (AmazonS3Exception ex)
        {
            Console.WriteLine($"\tError modifying retention period: '{ex.Message}'");
            return false;
        }
    }

To set an object retention configuration for an object

The following put-object-retention example sets an object retention configuration for the specified object until 2025-01-01.

aws s3api put-object-retention \
    --bucket my-bucket-with-object-lock \
    --key doc1.rtf \
    --retention '{ "Mode": "GOVERNANCE", "RetainUntilDate": "2025-01-01T00:00:00" }'

This command produces no output.

    // Set or modify a retention period on an object in an S3 bucket.
    public void modifyObjectRetentionPeriod(String bucketName, String objectKey) {
        // Calculate the instant one day from now.
        Instant futureInstant = Instant.now().plus(1, ChronoUnit.DAYS);

        // Convert the Instant to a ZonedDateTime object with a specific time zone.
        ZonedDateTime zonedDateTime = futureInstant.atZone(ZoneId.systemDefault());

        // Define a formatter for human-readable output.
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");

        // Format the ZonedDateTime object to a human-readable date string.
        String humanReadableDate = formatter.format(zonedDateTime);

        // Print the formatted date string.
        System.out.println("Formatted Date: " + humanReadableDate);
        ObjectLockRetention retention = ObjectLockRetention.builder()
            .mode(ObjectLockRetentionMode.GOVERNANCE)
            .retainUntilDate(futureInstant)
            .build();

        PutObjectRetentionRequest retentionRequest = PutObjectRetentionRequest.builder()
            .bucket(bucketName)
            .key(objectKey)
            .retention(retention)
            .build();

        getClient().putObjectRetention(retentionRequest);
        System.out.println("Set retention for "+objectKey +" in " +bucketName +" until "+ humanReadableDate +".");
    }

Example 1: The command enables governance retention mode untill the date '31st Dec 2019 00:00:00' for 'testfile.txt' object in the given S3 bucket.

Write-S3ObjectRetention -BucketName 's3buckettesting' -Key 'testfile.txt' -Retention_Mode GOVERNANCE -Retention_RetainUntilDate "2019-12-31T00:00:00"