I recently found out that you can fake directory structure on S3 by putting slashes in your filenames. That got me thinking: are there any restrictions at all on object IDs? I'm sure there must be some. Length? Null characters (\0)? Arcane stuff like invalid UTF-8 characters?
I'm sure there must be some restrictions, but I can't seem to find them anywhere in the documentation.
Per the S3 Technical FAQs and technical documentation:
A key is a sequence of Unicode characters whose UTF-8 encoding is at most 1024 bytes long.
Buckets names have additional restrictions:
To comply with Amazon S3 requirements, bucket names:
Can contain lowercase letters, numbers, periods (.), underscores (_), and dashes (-)
Must start with a number or letter
Must be between 3 and 255 characters long
Must not be formatted as an IP address (e.g., 192.168.5.4)
To conform with DNS requirements, we recommend following these additional guidelines when creating buckets:
Bucket names should not contain underscores (_)
Bucket names should be between 3 and 63 characters long
Bucket names should not end with a dash
Bucket names cannot contain two, adjacent periods
Bucket names cannot contain dashes next to periods (e.g., "my-.bucket.com" and "my.-bucket" are invalid)