docs: add S3-compatible adapter design

[bootjp]

No description provided.

[gemini-code-assist]

Summary of Changes

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This pull request introduces a comprehensive design document outlining the integration of an S3-compatible adapter into Elastickv. The proposed adapter aims to extend Elastickv's capabilities to include S3-like object storage, building upon its existing distributed systems infrastructure. The design details a robust data model, routing mechanisms, request flows for key S3 operations like PutObject and GetObject, and a strong consistency model. It also addresses authentication, failure handling, operational changes, observability, and a phased rollout strategy, ensuring a scalable and consistent S3 experience without full AWS parity.

Highlights

• S3-Compatible Adapter Introduction: A new HTTP adapter is proposed to expose an S3-like object API, reusing existing Elastickv Raft, MVCC, HLC, and shard-routing patterns.
• Strong Consistency Model: The design ensures strong read-after-write and list-after-write consistency for the current object view, leveraging a manifest-last write path.
• Large Object Handling: Objects larger than a single MVCC value will be supported by chunking data, with chunk writes not visible until the manifest is committed.
• HTTP Leader Proxy Requirement: An HTTP leader proxy is required to efficiently handle large S3 request and response bodies, avoiding the limitations of the current gRPC internal forwarding path.
• Core System Changes: Modifications to kv/routeKey and kv/ShardStore.routesForScan are necessary to properly recognize S3 internal prefixes and enable S3-aware internal scan mapping.
• Phased Rollout Plan: The S3 adapter will be rolled out in three phases, starting with core bucket and object operations, followed by multipart uploads and range reads, and finally virtual-hosted style and zero-copy CopyObject.

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[gemini-code-assist]

Code Review

This pull request introduces a comprehensive design document for a new S3-compatible adapter. The design is well-structured and covers key aspects such as the data model, request flows, consistency, and rollout plan. The proposed architecture leverages existing patterns within Elastickv, which is a good approach. I have a couple of suggestions to improve the clarity and completeness of the document.

[Copilot]

Pull request overview

Adds a design document for an S3-compatible HTTP adapter that fits into Elastickv’s existing adapter + Raft/MVCC/HLC/shard-routing architecture, with an emphasis on streaming large payloads via an HTTP leader-proxy and manifest-last object visibility.

Changes:

• Document proposed S3 API compatibility phases and request flows (Put/Get/List + multipart).
• Propose an internal keyspace + routing normalization model to keep object metadata/chunks shard-correct.
• Outline operational/config flags, observability, and a testing/rollout plan for incremental delivery.

[Copilot]

@bootjp I've opened a new pull request, #392, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 4 comments.

[bootjp]

@copilot open a new pull request to apply changes based on the comments in this thread

[Copilot]

@bootjp I've opened a new pull request, #393, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.