frostfs-s3-gw/docs/tree_service.md

Tree service

To get objects' metadata and system information, the S3 GW makes requests to the Tree service. This is a service in FrostFS storage that keeps different information as a tree structure.

Each node keeps one of the types of data as a set of key-value pairs:

• Bucket settings: lock configuration and versioning mode
• Bucket tagging
• Object tagging
• Object metadata: OID, name, creation time, system metadata
• Object locking settings
• Active multipart upload info

Some data takes up a lot of memory, so we store it in FrostFS nodes as an object with payload. But we keep these objects' metadata in the Tree service too:

• Notification configuration
• CORS
• Metadata of parts of active multipart uploads