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Module use_cases

d_engine::docs

Module use_cases 

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§Is d-engine Right for You?

Purpose: Help you quickly determine if d-engine fits your needs.

§What d-engine Provides

  • Strong consistency using Raft consensus algorithm
  • Leader election with automatic failover
  • Watch API for real-time change notifications
  • Two deployment modes: Embedded (Rust) or Standalone (any language via gRPC)

§Common Use Cases

§✅ Good Fit

1. Distributed Coordination

  • Leader election
  • Distributed locks
  • Cluster membership management

2. Metadata Storage

  • Service registry
  • Configuration management
  • Small shared state requiring strong consistency

3. Embedded Rust Applications

  • Need low-latency local access
  • Single binary deployment
  • Type-safe integration

§When NOT to Use

§❌ Not Suitable

  • Large-scale KV data storage
  • Applications requiring SQL interface

§Migrating from etcd?

d-engine shares etcd’s core ideas — Raft consensus, linearizable reads, watch streams — but it is not a drop-in replacement. It is a different point on the trade-off spectrum: simpler to operate, embeddable in Rust, but with a narrower API surface.

As of v0.2.4, if you are evaluating d-engine as an etcd alternative, check these gaps first:

etcd featured-engine status
Lease with keepalive✗ Not supported. d-engine has put_with_ttl, but keys cannot be renewed. Patterns relying on lease expiry for crash detection (service discovery, auto-releasing locks) are not directly portable.
Distributed lock (Lock API)✗ No built-in primitive. Can be approximated with compare_and_swap + watch, but without lease keepalive, safe auto-release on crash is not possible today.
Multi-key transactions (txn)Partial. d-engine has single-key compare_and_swap. Multi-key atomic operations are not supported.
Watch from historical revision✗ Watches start from the current state only. Use scan_prefix to rebuild state at reconnect, then resume watching from current. If your logic depends on start_revision to replay exact event history, this pattern will not fully substitute.
Auth / RBAC✗ Not available. All connected clients have full access.
Snapshot / backup✗ Not exposed via client API today.
Arbitrary range queries with limit/sortPartial. Only prefix scans; no cursor-based pagination.

What d-engine offers instead:

  • Zero-ops embedding: run coordination inside your Rust binary with no external process.
    etcd always requires a separate cluster; d-engine does not.
  • Explicit consistency API: choose Linearizable, Lease, or Eventual per read call — more granular than etcd’s serializable flag.
  • Pluggable storage backend: swap the storage engine without changing application code.

d-engine is a good fit when you want strong coordination guarantees with minimal infrastructure overhead. If you need the full etcd API surface — especially leases, distributed locks, or auth — etcd (or a compatible system) is the better choice today.

§Next Steps

If your use case matches → Choose Integration Mode

Created: 2025-12-30
Updated: 2026-05-24