cutelb 🐰

A cute, lightweight HTTP load balancer written in Haskell.

Features

• Multiple Load Balancing Strategies

  • Round Robin
  • Weighted Round Robin
  • Least Connections
  • Random
  • Least Response Time

• Flexible Routing

  • Exact path matching
  • Prefix matching
  • Regex matching

• Configuration

  • YAML-based configuration
  • Multiple upstream definitions
  • Optional access and error logging

Installation

Requires GHC and Cabal. Using Nix is recommended:

# With Nix
nix-shell

# Build
cabal build

# Run
cabal run cutelb -- config.yaml

Configuration

server:
  listen: 3000
  access_log: ./access.log  # optional
  error_log: ./error.log    # optional

upstreams:
  my_backend:
    strategy: round_robin  # or: weighted_round_robin, least_conn, random, least_response_time
    servers:
      - host: localhost
        port: 8001
      - host: localhost
        port: 8002
        weight: 2  # optional, for weighted_round_robin

routes:
  - path: /api
    upstream: my_backend
    match_type: prefix  # or: exact, regex

Usage

# Run with default config.yaml
cabal run cutelb

# Run with custom config
cabal run cutelb -- path/to/config.yaml

Testing

Start test backend servers:

python3 test/test_servers.py --test

Then run the load balancer:

cabal run cutelb -- test/config.yaml

Test with curl:

curl localhost:3000/api

License

MIT