Riak CS Storage API

The Riak CS storage API is compatible with the Amazon S3 REST API, which means that any of the operations listed can be executed using any of the commonly available S3 libraries or tools.

API Feature Comparison

The following table describes the support status for current Amazon S3 functional features.

Service-level Operations

• GET Service — Returns a list of all buckets owned by the user who sent the request

Bucket-level Operations

• GET Bucket — Returns a list of the objects within a bucket
• GET Bucket ACL — Returns the Access Control List (ACL) associated with a bucket
• GET Bucket policy — Gets the policy of a bucket
• PUT Bucket — Creates a new bucket
• PUT Bucket ACL — Sets the ACL permissions for a bucket
• PUT Bucket policy — Sets the policy for a bucket
• DELETE Bucket — Deletes a bucket
• DELETE Bucket policy — Deletes the policy of a bucket

Object-level Operations

• GET Object — Retrieves an object
• GET Object ACL — Returns the ACLs associated with an object
• PUT Object — Stores an object to a bucket
• PUT Object (Copy) — Creates a copy of an object
• PUT Object ACL — Sets the ACLs associated with an object
• HEAD Object — Retrieves object metadata (not the full content of the object)
• DELETE Object — Deletes an object

Multipart Upload

Multipart upload allows you to upload a single object as a set of parts. Object parts can be uploaded independently and in any order. After all parts are uploaded, Riak CS assembles an object out of the parts. When your object size reaches 100MB, you should consider using multipart uploads instead of uploading the object in a single operation. Read more about multipart uploads on the overview page.

• Initiate Multipart Upload — Initiates a multipart upload and returns an upload ID
• Upload Part — Uploads a part in a multipart upload
• Complete Multipart Upload — Completes a multipart upload and assembles previously uploaded parts
• Abort Multipart Upload — Aborts a multipart upload and eventually frees storage consumed by previously uploaded parts
• List Parts — Lists the parts that have been uploaded for a specific multipart upload.
• List Multipart Uploads — Lists multipart uploads that have not yet been completed or aborted.

Common Headers

• Common Riak CS Request Headers
• Common Riak CS Response Headers

There are two storage API options for Riak CS. The first and most fully featured is the S3 API. There is also limited but improving support for the OpenStack Object Storage API.

Riak CS can present different APIs by using the URL-rewriting capabilities of Webmachine. Configuring what API Riak CS uses is done by specifying the proper rewrite module in the configuration file. A rewrite module contains a set of rules for translating requests made using a particular API to requests in the native Riak CS API. The native API was designed to facilitate the organization and maintenance of the Riak CS Webmachine resource modules.

S3 API

• Module: riak_cs_s3_rewrite
• Documentation
• Mapping

Openstack Object Storage API (v1)

• Module: riak_cs_oos_rewrite
• Documentation
• Mapping

Selecting an API is done by adding or changing the rewrite_module key in the Riak CS riak-cs.conf file, or the old-style advanced.config or app.config files in the riak_cs section. For example, to instruct Riak CS to present the S3 API, ensure the following is contained in your configuration file:

rewrite_module = riak_cs_s3_rewrite

 {riak_cs, [
            %% Other configs
            {rewrite_module, riak_cs_s3_rewrite},
            %% Other configs
           ]}

 {riak_cs, [
            %% Other configs
            {rewrite_module, riak_cs_s3_rewrite},
            %% Other configs
           ]}

The S3 API is the default that is set in the configuration that is included when installing a Riak CS package or building from source.

More details for each option can be found by following one of the following links:

• S3 API
• OpenStack API