Go

The S3 gateway: SigV4, S3-compliant XML errors, Head/List/Copy, pagination, ranges, and metadata — a compatible API surface for real clients.

Envelope encryption with a client-held key: the server stores ciphertext and can’t read it — across S3 and native transports.

Momo’s transport layer grew from TCP to a QUIC/TLS 1.3 fan-out — fixing handshake, ACK framing, deadlines, and TLS identity along the way.

A 76-deep audit (authed via Sentinel) surfaced CRLF injection, smuggling, traversal and path leaks — the pattern that forged momo’s security mindset.

The [storage] backend seam swaps blob storage (local, nfs, s3, raw) behind one Store interface, keeping CAS metadata local.

Weighted rendezvous hashing picks replicas deterministically and peer-equally without a central allocator — later hardened for failure domains. Teaches: content-hash-based placement, weighted rendezvous hashing, deterministic stable sort, failure domain filtering.

Chain, Splay, and Primary-Splay replication — and the metrics-driven controller that switches between them at runtime.

Identify every object by its SHA-256 content hash — server-side dedup, verify-on-read, and a path that later mounted a filesystem. Teaches: content addressing principles, single write chokepoint, Bolt/Sentinel patterns.

A scaleless-gossip ring: SWIM-style failure detection, discovered-peer dialing, and ALIVE/OFFLINE restoration — momo’s nervous system.

How momo started as a file-replication playground in Go and grew into a distributed content-addressed object store.