crabdis

It’s like Redis but a bit rusty.

crabdis is a small, in-memory key-value store written in Rust that speaks the Redis protocol (RESP).

[!NOTE] This project is experimental. Use in production only if you’re comfortable with sharp edges.

What’s implemented

• RESP2 by default, with optional RESP3 via HELLO 3
• Core key/value operations (strings + integers)
• Hashes
• Key expiry (EXPIRE/TTL/etc.)
• Pub/Sub (RESP2 arrays / RESP3 push)
• RDB persistence (load on boot + SAVE/BGSAVE + periodic auto-save)

Known to work with clients like redis-cli, ioredis, and Bun’s Redis client, but compatibility is not guaranteed.

Install

• Releases: download prebuilt binaries from https://github.com/pxseu/crabdis/releases
• Cargo: cargo install crabdis
• Docker: pxseu/crabdis on Docker Hub

Quickstart

Run locally:

crabdis

Connect with redis-cli:

redis-cli -p 6379 ping

Docker

The Docker image disables persistence by default (it runs with --save "").

docker run --rm -p 6379:6379 pxseu/crabdis:latest

To enable persistence, mount a volume and pass --dir and one or more --save points:

docker run --rm -p 6379:6379 \
  -v crabdis_data:/data \
  pxseu/crabdis:latest \
  --dir /data --save "60 1"

(See docker-compose.yml for an example setup.)

Configuration

Run crabdis --help for the full list. Common flags:

• --address / --port: bind address and port (Unix defaults to ::, Windows defaults to 127.0.0.1)
• --threads: Tokio worker threads
• --verbose: enable verbose logging
• --dir / --dbfilename: RDB location (defaults to ./dump.rdb)
• --save "SECONDS CHANGES": auto-save points; pass --save "" to disable RDB persistence
  • If you don’t specify any --save points, Crabdis uses defaults: 3600 1, 300 100, 60 10000

Supported commands

Crabdis supports a (growing) subset of Redis commands. Highlights:

• Core: GET, SET (incl. EX/PX/NX/XX), DEL, EXISTS, KEYS, SCAN, TYPE, DBSIZE, FLUSHDB, SELECT, RENAMENX
• Multi-key: MGET, MSET
• Counters: INCR, DECR
• Expiry: EXPIRE, TTL, PTTL, PERSIST, SETEX, PSETEX
• Hashes: HSET, HGET, HGETALL, HDEL, HEXISTS, HLEN
• Pub/Sub: PUBLISH, SUBSCRIBE, UNSUBSCRIBE
• Server/Protocol: PING, QUIT, INFO, HELLO, COMMAND / COMMAND DOCS, CLIENT, CONFIG
• Persistence: SAVE, BGSAVE, LASTSAVE

For client compatibility, prefer discovering capabilities via COMMAND/COMMAND DOCS rather than assuming Redis parity.

Not implemented (yet)

• Lists, Sets, Sorted Sets
• Replication, clustering, ACLs
• Lua scripting, transactions, modules

Development

• Build: cargo build --release
• Run: cargo run -p crabdis
• Test: cargo test
• Bench (core values + RESP): cargo bench -p crabdis-core

License

MIT License, see LICENSE.