This requires an extra `ListAllMyBuckets` api call and permission, which isn't necessary to check for existence of a specific bucket. Instead, you can make a HEAD request against the specific bucket via the Getting a Bucket strategy [here](http://docs.aws.amazon.com/AWSRubySDK/latest/AWS/S3/Bucket.html):

```ruby
bucket = s3.buckets['bucket-name'] # makes no request
bucket.exists? #=> returns true/false
```