shar-teel

Consistently shard a value in any given array.

Installation

yarn install shar-teel

Usage

const sharTeel = require('shar-teel');

// This is the array of possible values
const servers = ["amn", "baldur", "cormyr"];

// This is the key on which to shard. It can be anything: an id, an email, an url, etc
const key = "[email protected]";

// This is the shard, one of the three possible server, randomly selected
// The same key will consistently return the same shard
const shard = sharTeel(servers, key)

Why would I need this?

This can be used in a load-balancing logic. You might want to split your traffic between different servers, read your data from different replica databases or parrallelize heavy operation accross different machines.

shar-teel helps in picking a random value out of a set, in a consistent way. This means that running the same sharTeel(possibleValues, key) is idempotent and will always return the same value.

Why this name?

shard was already taken as an npm module. I tend to name my projects from characters of my favorite books and video games. Shar-Teel is a character in Baldur's Gate.