Controlling access to buckets and objects on Amazon S3

Once the object is stored in the bucket, the next major step is to manage access. S3 is private by default, and access is given to other users, groups, or resources via several methods. This means that access to the objects can be managed via Access Control Lists (ACLs), Public Access Settings, Identity Policies, and Bucket Policies.

Let’s look at some of these in detail.

S3 bucket policy

An S3 bucket policy is a resource policy that is attached to a bucket. Resource policies decide who can access that resource. It differs from identity policies in that identity policies can be attached or assigned to the identities inside an account, whereas resource policies can control identities from the same account or different accounts. Resource policies control anonymous principals too, which means an object can be made public through resource policies. The following example policy allows everyone in the world to read the...