Application Configuration

• Define and initialise Typescript-friendly global read-only application configuration in runtime.

• Populate each config value using either a value (or source of value, e.g. function) (fromVal), an inline function (fromFunc), or the environment variable parser (fromEnv).

• Validate config values using Zod schema validation library, optionally using built-in base schemas: String, Number, Int, BigInt, and Boolean.

How to Use

1. Create a config.ts file:

   This file will define and export your app configuration.

   Import and use createConfig({...}) to define the configuration.

   import { Boolean, Integer, String, configVar, createConfig, fromEnv, fromFunc, fromVal } from "../src";
   
   const config = createConfig({
       // config can be sourced from env vars using `fromEnv`
       // "REQUIRED" will ensure error is thrown if env var has not been set
       hostUrl: configVar("Host URL", "REQUIRED", String.url())(fromEnv("HOST")),
       // config can be sourced from (in-line) functions using `fromFunc`
       timeout: configVar("Timeout (in seconds)", "REQUIRED", Int)(fromFunc(()=>{
           const minCeiled = Math.ceil(5);
           const maxFloored = Math.floor(10);
           return Math.floor(Math.random() * (maxFloored - minCeiled + 1) + minCeiled); // The maximum is inclusive and the minimum is inclusive
       })
       ),
       // config can be sourced from pre-defined values or existing functions using `fromVal`
       // this example uses a custom schema
       protocol: configVar("Protocol", "REQUIRED", AvailableProtocol)(fromVal("HTTP")),
       // configs can be nested
       a: {
           b: {
               c: {
                   portNumber: configVar("Port Number", "REQUIRED", Int)(fromEnv("PORT"))
               },
           }
       },
       // env vars can be parsed as boolean, the following (case-insensitive) evaluate to TRUE: "true", "yes", "t", "y"
       // "OPTIONAL" means error will NOT be thrown if env var has not been set, will instead evaluate to FALSE (for boolean schema) or UNDEFINED (for non-boolean schema).
       forceTLS: configVar("Force Transport Layer Security (TLS)", "OPTIONAL", Boolean)(fromEnv("FORCE_TLS"))
   });

2. Access your configuration from other source files:

   import config from "config.ts"
   
   console.log(config.a.b.c.portNumber);
   // 8080
   
   console.log(typeof config.a.b.c.portNumber);
   // number