You can configure back-to-origin rules for a bucket. If a request is sent to access an object but the object does not exist in a bucket for which back-to-origin rules are configured, Object Storage Service (OSS) obtains the requested object from the origin specified by the back-to-origin rules. You can configure mirroring-based or redirection-based back-to-origin rules for hot migration and specific request redirection.

For more information, see Manage back-to-origin configurations.

Mirroring-based back-to-origin

After you configure mirroring-based back-to-origin rules for a bucket, if a requester accesses an object but the object does not exist in a bucket, OSS obtains the object from the origin specified by the back-to-origin rules. OSS returns the object obtained from the origin to the requester and stores the object in the bucket. For more information about how to configure mirroring-based back-to-origin rules, see Basic configurations of mirroring-based back-to-origin.

Mirroring-based back-to-origin is used to migrate data to OSS. This feature allows you to migrate a service that already runs on an origin that you create or on another cloud service to OSS without service interruptions. You can use mirroring-based back-to-origin rules during migration to obtain the data that is not migrated to OSS. This ensures service continuity. For detailed examples, see Seamlessly migrate data of a web-based service provider to OSS.

Redirection-based back-to-origin

After you configure redirection-based back-to-origin rules for a bucket, if an error occurs when a requester accesses the bucket, OSS redirects the request to the origin specified by the redirection-based back-to-origin rules. You can use this feature to redirect requests for objects and develop various services based on redirection. For more information about how to configure redirection-based back-to-origin rules, see Configure redirection-based back-to-origin.

Rules

You can configure up to 20 back-to-origin rules for a bucket in the OSS console. By default, the rules are used to match a request in the sequence that they are configured. You can click Move Up or Move Down on the right side of the rules to change the priority of the rules.
Notice If a request matches a rule, subsequent rules are not used to match the request. OSS determines whether a request matches a back-to-origin rule based on whether the request meets the conditions specified in the rule. OSS does not check whether a request can obtain the requested object from the origin.
3