Does Amazon S3 support symlinks?
I have an object which I would like to address using different keys without actually copying the object itself, like a symlink in Linux. Does Amazon S3 provide such a thing?
Answer
S3 does not support the notion of a symlink, where one object key is treated as an alias for a different object key. (You've probably heard this before: S3 is not a filesystem. It's an object store).
If you are using the static web site hosting feature, there is a partial emulation of this capability, with object-level redirects:
http://docs.aws.amazon.com/AmazonS3/latest/dev/how-to-page-redirect.html
This causes requests for "object-a" to be greeted with a 301 Moved Permanently response, with the URL for "object-b" in the Location: header, which serves a similar purpose, but is of course still quite different. It only works if the request arrives at the website endpoint (not the REST endpoint).
If you use a reverse proxy (haproxy, nginx, etc.) in EC2 to handle incoming requests and forward them to the bucket, then of course you have the option at the proxy layer of rewriting the request URL before forwarding to S3, so you could translate the incoming request path to whatever you needed to present to S3. How practical this is depends on your application and motivation, but this is one of the strategies I use to modify where, in a particular bucket, an object appears, compared to where it is actually stored, allowing me to rewrite paths based on other attributes in the request.