How to redirect from bucket root to subdirectory in AWS S3?

Question

I have an amazon S3 bucket serving a website from S3bucketurl.com/foo/index.html.

I would like to configure a redirection rule, that automatically rewrite the URL as follows:

Accessing S3bucketurl.com should automatically redirect to S3bucketurl.com/foo, and serve the index.html file contained in the subfolder foo.

I tried to set up the Redirection Rule as such:

<RoutingRules>
  <RoutingRule>
    <Condition>
      <KeyPrefixEquals>/</KeyPrefixEquals>
    </Condition>
    <Redirect>
      <ReplaceKeyWith>api</ReplaceKeyWith>
    </Redirect>
  </RoutingRule>
</RoutingRules>

which results in a 404:

404 Not Found

Code: NoSuchKey
Message: The specified key does not exist.
Key: index.html

I've also tried permutations of <ReplaceKeyWith>/api</ReplaceKeyWith>, <ReplaceKeyWith>api/</ReplaceKeyWith> and <ReplaceKeyWith>/api/</ReplaceKeyWith> to no avail.

Answer 1

<KeyPrefixEquals>/</KeyPrefixEquals>

There are two problems, here: first, this matches a prefix, meaning there's an implicit * at the end. Thst isn't what you want, here. Also no key in an S3 bucket typically has a prefix of /. The object key starts with the character after the leading slash. Your <ReplaceKeyWith> is ignored because the prefix test never matches. But rules are not the best solution, here.

The way to do what you want is this:

Upload an empty file to create a new object in the root of the bucket, named whatever name you use for your index documents, typically index.html. Make it public unless your bucket policy makes everything public.

In the object metadata for this object, set x-amz-website-redirect-location to /api/ (or /foo/, or whatever path you intend).