Crabis

A minimal Redis-like key/value store written in .

It listens on the default Redis port (6379) and supports a tiny subset of the Redis protocol.

Available commands

• HEALTH
  Simple health check.
  Example: HEALTH → OK

• SET key value
  Stores a string value under a string key.
  Example: SET mykey hello → OK

• GET key
  Retrieves the value for a given key or returns a null bulk string if it does not exist.
  Example: GET mykey → hello

Example

How it works

Crabis uses a TcpListener from tokio to accept incoming TCP connections on port 6379.

Each connection is handled in its own asynchronous task using tokio::spawn, so multiple clients can be served concurrently without blocking the main thread.

For storage, it relies on a DashMap, a concurrent hash map. This means multiple tasks can read and write keys at the same time safely and efficiently, without manually managing locks.

Prerequisites

• redis-cli installed

Getting started

From the project root, you can build and run the server with:

• Using Cargo

  • cargo build
  • cargo run

• Using Makefile

  • make start

Crabis now listens on 127.0.0.1:6379.

In another terminal, you can connect with:

redis-cli -h 127.0.0.1 -p 6379

You can also enable the Append Only File (AOF) mode to persist SET commands to disk:

cargo run -- AOF

In AOF mode, every SET key value is appended to a log file so the in-memory store can be reconstructed on restart.

Q&A

Q: Why “Crabis”? What is this stupid name?
A: The project is inspired by Redis (it contains “Red”), and since it’s written in Rust, which is associated with the color orange, I first thought about calling it “Orangeis", but that sounded a bit odd. Since Rust’s mascot is an orange crab, I came up with “Crabis.”